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"Heatshield" - More reefer (well, insulation) questions
One of my respondents to my question about vacuum panels is very high on
"Heat Shield" (www.heatshieldmarine.com) - a mostly radiant barrier, to my expectations, but their claim is that in conjunction with foam, it has the effect of tripling the foam R value. As I don't know what's inside these foil separators (1/2, 3/4 and 1 inch material) I can't judge the insulating value of that part. However, what I *think* I know (see Mark Twain's quotation about facts for perspective) is that a radiant barrier can be any shiny surface - such as on the outside of Tuff-R or other building supply foam board, or simple home aluminum foil - including, I suppose, those Mylar "space blankets" available cheaply in camping stores Despite their assertions that their 1" is equivalent to 5 or 6" of urethane foam, as their site seems to place a great deal of importance on the radiant barrier, I don't know how much value to place on *their* radiant barrier over any other. It seems to me that if this premise were so, houses would be insulated with silver Mylar film outside instead of the usual tyvek wrap as it seems - at least from the premise of their claims - it would improve the thermal barrier multifold. Not being a thermal engineer, I don't know whose claims to believe... So, again, I'm looking for real-world experience. Anyone had an installation of Heat Shield they'd care to comment on? Thanks. L8R Skip and Lydia -- Morgan 461 #2 SV Flying Pig http://tinyurl.com/384p2 "Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover." - Mark Twain |
For what it's worth:
I am, among other things, a "Certified Infrared Thermographer" (Infraspection Institute). I have several years experience with using infrared cameras to inspect electrical systems, building envelopes, and industrial processes. In addition, I have taught these skills to others in formal classes. In simple terms, there are three methods of transferring heat: 1) Conduction 2) Convection 3) Radiation 1) Conduction - If two materials are touching each other heat will be transferred from the warmer to the cooler. 2) Convection - If two materials are separated by a liquid or gas the heat can be transferred from one material to the other through the motion of the liquid or gas. 3) Radiation - All materials give off infrared radiation from their surfaces. This radiation is just below the lower end of visible light and extends down to microwave frequencies. The qualities of the surface determine the "Emissivity" of the surface. A perfect radiator has an emissivity of one. A perfect cold dark body has an emissivity of zero. Real world objects are between these two extremes. Highly reflective surfaces usually have a very low emissivity and will not radiate heat efficiently nor absorb very much heat energy. This is why gold foil is used to cover certain areas of satellites. It protects them from the suns infrared radiation. It's also why the space shuttle must roll over with it's top facing earth and it's bay doors open soon after reaching orbit. It's cooling radiators (high emissivity) are inside the cargo bay and they must be kept exposed to the outside and facing away from the sun at all times. Since they have no means of removing heat by conduction or convection in outer space, they must do it by infrared radiation. After that very simplified beginning, on to reflective barriers. A reflective barrier can greatly reduce the heat gain to a cool object from infrared radiation. The question is, where to put it? If you have an insulated ice box you could put it on the outside surface. It would then reduce heat gain from infrared radiation. However, it would do nothing to reduce heat gain from convection. The warm air surrounding the outside of the box would transfer heat to, and through, the reflective surface just as if it was painted flat black. In addition, since the reflective foil was in contact with the outside of the box, conduction would just move the heat right into your ice box. You could put it on the inside of the box, with the shiny side facing out. In this case the foil would be in contact with the material forming the box and again conduction would pass the heat right through the foil. The same problem occurs no matter where you place the foil. Conduction or convection always wins. The only solution I know would be to build an inner box, cover it with shiny foil, and surround that with a layer of vacuum to eliminate convection and conduction. Even then, heat gain through infrared radiation would be the least of your concerns. The closest practical solution is to use insulated vacuum panels like those built by Glacier Bay and others. They have a real life insulating rating of R50 per inch. But, you will pay for that luxury. I can think of one place a reflective foil might help. If you had a freezer or refrigerator, with adequate vacuum or foam insulation, that had one side facing the inside of you engine room then foil on that surface facing the engine would reduce infrared heat gain to the box when running the engine. But that can also be covered with Mylar faced noise control foam with even better results. The bottom line: Most heat gain to a refrigerated box is through convection and conduction, not infrared radiation. There is no free ride and reflective foils will not noticeably improve the insulating qualities of the typical boat ice box. Rusty O Reflective barriers "Skip Gundlach" skipgundlach sez use my name at earthlink dot fishcatcher (net) - with apologies for the spamtrap wrote in message ... One of my respondents to my question about vacuum panels is very high on "Heat Shield" (www.heatshieldmarine.com) - a mostly radiant barrier, to my expectations, but their claim is that in conjunction with foam, it has the effect of tripling the foam R value. |
Rusty, you take measurements for a living, but are not a design eng. a couple
of things to make note of: 1.) "shiney" is shiney from both sides, as far as radiation is concerned. shiney out or shiney in, same same. 2.) shiney on the outside does NOT make for greater (or lesser) conductivity or convectivity. shiney on the outside makes for reflection of the radiant heat **from the outside** (where heat is in a reefer system). shiney on the inside means some of the radiant heat is absorbed on the way through the insulation (makes for warmer insulation) and then is reflected back into the insulation where some of it is also absorbed (making for even warmer insulation). 3. You, Rusty, sound like a shill for N. Bruce Nelsen of Glacier Bay, a man who over the years has made one hell of a lot of claims that don't stand close examination. 4.) "vacuum" panels are not vacuum at all, but rather are panels with a plastic latice inside (to hold the sides of the panel apart) with much, but by no means all, of the air removed. (air pressure is 14.7 pounds PER SQUARE INCH, so a 1 square foot panel encasing a true vacuum would have over 2,000 pounds pressure trying to collapse the sides. For what it's worth: I am, among other things, a "Certified Infrared Thermographer" (Infraspection Institute). I have several years experience with using infrared cameras to inspect electrical systems, building envelopes, and industrial processes. In addition, I have taught these skills to others in formal classes. In simple terms, there are three methods of transferring heat: 1) Conduction 2) Convection 3) Radiation 1) Conduction - If two materials are touching each other heat will be transferred from the warmer to the cooler. 2) Convection - If two materials are separated by a liquid or gas the heat can be transferred from one material to the other through the motion of the liquid or gas. 3) Radiation - All materials give off infrared radiation from their surfaces. This radiation is just below the lower end of visible light and extends down to microwave frequencies. The qualities of the surface determine the "Emissivity" of the surface. A perfect radiator has an emissivity of one. A perfect cold dark body has an emissivity of zero. Real world objects are between these two extremes. Highly reflective surfaces usually have a very low emissivity and will not radiate heat efficiently nor absorb very much heat energy. This is why gold foil is used to cover certain areas of satellites. It protects them from the suns infrared radiation. It's also why the space shuttle must roll over with it's top facing earth and it's bay doors open soon after reaching orbit. It's cooling radiators (high emissivity) are inside the cargo bay and they must be kept exposed to the outside and facing away from the sun at all times. Since they have no means of removing heat by conduction or convection in outer space, they must do it by infrared radiation. After that very simplified beginning, on to reflective barriers. A reflective barrier can greatly reduce the heat gain to a cool object from infrared radiation. The question is, where to put it? If you have an insulated ice box you could put it on the outside surface. It would then reduce heat gain from infrared radiation. However, it would do nothing to reduce heat gain from convection. The warm air surrounding the outside of the box would transfer heat to, and through, the reflective surface just as if it was painted flat black. In addition, since the reflective foil was in contact with the outside of the box, conduction would just move the heat right into your ice box. You could put it on the inside of the box, with the shiny side facing out. In this case the foil would be in contact with the material forming the box and again conduction would pass the heat right through the foil. The same problem occurs no matter where you place the foil. Conduction or convection always wins. The only solution I know would be to build an inner box, cover it with shiny foil, and surround that with a layer of vacuum to eliminate convection and conduction. Even then, heat gain through infrared radiation would be the least of your concerns. The closest practical solution is to use insulated vacuum panels like those built by Glacier Bay and others. They have a real life insulating rating of R50 per inch. But, you will pay for that luxury. I can think of one place a reflective foil might help. If you had a freezer or refrigerator, with adequate vacuum or foam insulation, that had one side facing the inside of you engine room then foil on that surface facing the engine would reduce infrared heat gain to the box when running the engine. But that can also be covered with Mylar faced noise control foam with even better results. The bottom line: Most heat gain to a refrigerated box is through convection and conduction, not infrared radiation. There is no free ride and reflective foils will not noticeably improve the insulating qualities of the typical boat ice box. Rusty O Reflective barriers "Skip Gundlach" skipgundlach sez use my name at earthlink dot fishcatcher (net) - with apologies for the spamtrap wrote in message ... One of my respondents to my question about vacuum panels is very high on "Heat Shield" (www.heatshieldmarine.com) - a mostly radiant barrier, to my expectations, but their claim is that in conjunction with foam, it has the effect of tripling the foam R value. |
A-men brother.
The Heat Shield folks do a demo at boat shows where they wrap an Igloo cooler in the stuff and compare the ice melt to a bare cooler. The problem is they sit the coolers in the sun where 90% of the load is radiant. That will not be the case in the galley. One place I do plan to use a Heat Shield like product in between the head liner and the cabin top where the load will be mostly radiant. But I will be using that silver Mylar and bubble wrap duct insulation from Home Despot. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "Rusty O" wrote in message ink.net... For what it's worth: I am, among other things, a "Certified Infrared Thermographer" (Infraspection Institute). I have several years experience with using infrared cameras to inspect electrical systems, building envelopes, and industrial processes. In addition, I have taught these skills to others in formal classes. In simple terms, there are three methods of transferring heat: 1) Conduction 2) Convection 3) Radiation 1) Conduction - If two materials are touching each other heat will be transferred from the warmer to the cooler. 2) Convection - If two materials are separated by a liquid or gas the heat can be transferred from one material to the other through the motion of the liquid or gas. 3) Radiation - All materials give off infrared radiation from their surfaces. This radiation is just below the lower end of visible light and extends down to microwave frequencies. The qualities of the surface determine the "Emissivity" of the surface. A perfect radiator has an emissivity of one. A perfect cold dark body has an emissivity of zero. Real world objects are between these two extremes. Highly reflective surfaces usually have a very low emissivity and will not radiate heat efficiently nor absorb very much heat energy. This is why gold foil is used to cover certain areas of satellites. It protects them from the suns infrared radiation. It's also why the space shuttle must roll over with it's top facing earth and it's bay doors open soon after reaching orbit. It's cooling radiators (high emissivity) are inside the cargo bay and they must be kept exposed to the outside and facing away from the sun at all times. Since they have no means of removing heat by conduction or convection in outer space, they must do it by infrared radiation. After that very simplified beginning, on to reflective barriers. A reflective barrier can greatly reduce the heat gain to a cool object from infrared radiation. The question is, where to put it? If you have an insulated ice box you could put it on the outside surface. It would then reduce heat gain from infrared radiation. However, it would do nothing to reduce heat gain from convection. The warm air surrounding the outside of the box would transfer heat to, and through, the reflective surface just as if it was painted flat black. In addition, since the reflective foil was in contact with the outside of the box, conduction would just move the heat right into your ice box. You could put it on the inside of the box, with the shiny side facing out. In this case the foil would be in contact with the material forming the box and again conduction would pass the heat right through the foil. The same problem occurs no matter where you place the foil. Conduction or convection always wins. The only solution I know would be to build an inner box, cover it with shiny foil, and surround that with a layer of vacuum to eliminate convection and conduction. Even then, heat gain through infrared radiation would be the least of your concerns. The closest practical solution is to use insulated vacuum panels like those built by Glacier Bay and others. They have a real life insulating rating of R50 per inch. But, you will pay for that luxury. I can think of one place a reflective foil might help. If you had a freezer or refrigerator, with adequate vacuum or foam insulation, that had one side facing the inside of you engine room then foil on that surface facing the engine would reduce infrared heat gain to the box when running the engine. But that can also be covered with Mylar faced noise control foam with even better results. The bottom line: Most heat gain to a refrigerated box is through convection and conduction, not infrared radiation. There is no free ride and reflective foils will not noticeably improve the insulating qualities of the typical boat ice box. Rusty O Reflective barriers "Skip Gundlach" skipgundlach sez use my name at earthlink dot fishcatcher (net) - with apologies for the spamtrap wrote in message ... One of my respondents to my question about vacuum panels is very high on "Heat Shield" (www.heatshieldmarine.com) - a mostly radiant barrier, to my expectations, but their claim is that in conjunction with foam, it has the effect of tripling the foam R value. |
Jax, you still don't understand the principle that it is better to keep your
mouth shut and have people think you are stupid than opening it and confirming the fact. Most vacuum panels are filled with Instil, an inert open celled silica based foam board from Dow. It has a crush strength of about 50 PSI, well above the 14.7 atmospheric pressure, and an R value at standard pressure of about 5. At 1 milibar vacuum the R value is about 25 and at .1 milibar it is about 30. Glacier Bay uses a special reinforced aerogel material called Nanogel made by Cabot (the Cabosil people) with an R value at standard pressure of about 15. While the bare material is extremely delicate its latticework structure makes it very strong under even compression. At 10 milibar the R value is about 30 and at .1 milibar it is about 50. The curve of vacuum to R value is flatter with Nanogel than with Instil. The obvious advantage is that as the panel loose vacuum the Nanogel will maintain more insulation value. The disadvantage is that Nanogel is much more expensive and harder to work with. The problem with all vacuum insulation is that it is impossible to maintained a high vacuum with a low conductivity flexible membrane. Air molecules will slowly find a way in. Back in the 80s a vacuum panel made of a stainless envelope packed with precipitated silica was popular in refrigerated containers and some high end European refrigerators. It was only effective in large sizes because the steel conducted a lot of heat around the edges. In the mid 90s Toyo and Dupont developed films consisting of several layers of various UHMW plastics coated with a very thin layer of aluminum that made smaller panels practical and easier to fabricate. Those films have been greatly improved over the last 5 years. Around the same time SAES introduced a room temperature getter material to absorb stray gas molecules and packages it in small inexpensive pucks to be inserted in the panels. The net result is that you can reasonably expect 10 to 15 years of R values better than 25 per inch from almost any well constructed vacuum insulation panel. The Glacier Bay Panels will last about 30% longer and have the distinct advangate of maintaining a reasonable level of insulation even with no vacuum. The down side is that they are about twice as expensive. Regardless, marine refrigerators made with vacuum insulation should be built with the need to eventually replace the panels in mind. I am counting on 8 to 10 years and will probably replace them even if they are still reasonably effective. At the present rate of improvement by then the technology will be far better and the prices significantly lower. BTW, you should NOT use two part pour in place foam to fill gaps between vacuum panels. Two part foams produce a lot of heat as they cure. The vacuum panels are so effective that they will trap the heat and possibly damage the plastic film. Moisture curing spray foam like Great Stuff is a lot safer. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "JAXAshby" wrote in message ... Rusty, you take measurements for a living, but are not a design eng. a couple of things to make note of: 1.) "shiney" is shiney from both sides, as far as radiation is concerned. shiney out or shiney in, same same. 2.) shiney on the outside does NOT make for greater (or lesser) conductivity or convectivity. shiney on the outside makes for reflection of the radiant heat **from the outside** (where heat is in a reefer system). shiney on the inside means some of the radiant heat is absorbed on the way through the insulation (makes for warmer insulation) and then is reflected back into the insulation where some of it is also absorbed (making for even warmer insulation). 3. You, Rusty, sound like a shill for N. Bruce Nelsen of Glacier Bay, a man who over the years has made one hell of a lot of claims that don't stand close examination. 4.) "vacuum" panels are not vacuum at all, but rather are panels with a plastic latice inside (to hold the sides of the panel apart) with much, but by no means all, of the air removed. (air pressure is 14.7 pounds PER SQUARE INCH, so a 1 square foot panel encasing a true vacuum would have over 2,000 pounds pressure trying to collapse the sides. |
Rusty, thank you so much for your informed and concise presentation. It's
very complete, and answers most of my questions, but generates a couple of others. Please indulge me? And, since you're spamtrapped, I can't ask you directly, but may I quote you in the various mailing lists to which I posed the same question(s)? A reflective barrier can greatly reduce the heat gain to a cool object from infrared radiation. The question is, where to put it? (exposition clipped) The bottom line: Most heat gain to a refrigerated box is through convection and conduction, not infrared radiation. There is no free ride and reflective foils will not noticeably improve the insulating qualities of the typical boat ice box. So, effectively, without a vacuum (or, at least, a free-space non-touching environment), the addtion of aluminum foil merely acts to accelerate (aluminum being an excellent heat conductor) heat transfer? Thus, for example, the foil-faced building insulation products are no better than the level of vacuum behind them? I'd been migrating to the thought of layering heavy foil between the highest R-value foam I could find, and then doing a heat-sealed vapor barrier wrap, evacuated to the best of my ability. However, your comments suggest that's a waste of time. I *think* I understand you to say that foil is counterproductive if not faced with a vacuum. If so, from that, if I'm not going to spring for the vacuum panels, simple block foam, encapsulated to prevent moisture, is the best? My box exterior (which is a single layer of roving over the hard urethane 2") is currently exposed for most of two sides. I'd thought to put foil on that exterior surface. If I understand you properly, that's counterproductive? On to the last: I can think of one place a reflective foil might help. If you had a freezer or refrigerator, with adequate vacuum or foam insulation, that had one side facing the inside of you engine room then foil on that surface facing the engine would reduce infrared heat gain to the box when running the engine. But that can also be covered with Mylar faced noise control foam with even better results. Is that like the lead foam used in noise control, nearly as expensive as heat shield :{)) ? Or is there some other noise abatement of which I'm not aware (there are probably encyclopediea worth of info of which I'm not aware!)? Is this an application where a foil-backed insultion board would help? Thanks again for your knowledgeable input. L8R Skip and Lydia Rusty O -- Morgan 461 #2 SV Flying Pig http://tinyurl.com/384p2 "Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover." - Mark Twain |
Is that like the lead foam used in noise control, nearly as expensive as heat shield :{)) ? Or is there some other noise abatement of which I'm not aware (there are probably encyclopediea worth of info of which I'm not aware!)? Is this an application where a foil-backed insultion board would help? That is correct. It is opencell foam either side of a rubber membrane imbedded with lead and a foil face. I don't think you really have that option though. You would have to rip everything off that front engine room wall and having seen it I do not believe you really want to do that. :-) A little clarification: Once the radiant energy is absorbed it becomes conductive and the metal actually speeds up transmission. If the foil is behind another layer that absorbs radiant energy, like the wood face of the refrigerator it looses much of its effectiveness because the radiant energy has already been converted to conductive. The foil side on foam or fiberglass insulation goes on the warm side. It reflects some of the remaining radiant load but mostly it acts as a moisture barrier. With your galley layout you have two places where the fridge will be subject to radiant load. The side of the stove where it sits beside the outboard end of the box and the back side against the engine room. You are cutting down the size of the box (Seriously folks, this box is big enough to fit two coffins in.) so if you go with vacuum insulation you might consider turning that far end into pot storage. The front wall of the engine room might be a good candidate for some foil insulation. (Not nessacarily Heat Shield) It will be easier to install than SoundDown and sound insulation is useless unless you completely cover all the room surfaces. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com |
So, effectively, without a vacuum (or, at least, a free-space non-touching
environment), the addtion of aluminum foil merely acts to accelerate (aluminum being an excellent heat conductor) heat transfer? Yes, the heat would tend to conduct right through the aluminum. However, given that the materials on each side would tend to have lower levels of conduction, the aluminum probably has no effect either way. In other words, if you sandwiched a layer of foil between two layers of insulation, the overall conduction would be nearly the same as the insulation layers alone. Thus, for example, the foil-faced building insulation products are no better than the level of vacuum behind them? I'm not sure what the advantage of foil-faced foam board is over non-faced foam board in housing applications. I have a call in to my brother who is a building materials guru. I will pass on the information when I hear from him. I'd been migrating to the thought of layering heavy foil between the highest R-value foam I could find, and then doing a heat-sealed vapor barrier wrap, evacuated to the best of my ability. However, your comments suggest that's a waste of time. Yes, I believe that would be a waste of time. My hot tub cover had a heat sealed vapor barrier around the foam insulation. After a few years it got so heavy from trapped moisture, I had to replace it. And, that was after unwrapping it and letting it dry in the sun for three months. I *think* I understand you to say that foil is counterproductive if not faced with a vacuum. If so, from that, if I'm not going to spring for the vacuum panels, simple block foam, encapsulated to prevent moisture, is the best? Yes, the foam is then the best way. Some other thoughts: 1) Wet insulation is an excellent heat conductor 2) When insulation gets wet, it can be almost impossible to dry out. 3) It's almost impossible to totally encapsulate the insulation around a boat ice box. 4) Imperfections will allow air to move in and out of the insulation. 5) When the air is cool and dense it will migrate into the insulation. 6) When the air is warmed it will expand, release its moisture, and move out. 7) After enough cycles of cooling and warming, the insulation will be wet from the released moisture. This is why you have a vapor barrier in your house between the interior and the insulation, but not on the outside. These problems can be minimized by not trying to encapsulate the insulation. Give it a way to dry out between cycles. Also, try to use closed cell foam instead of open cell. You can test your insulation before installing it buy breaking off a small piece, carefully weigh it, put it in a glass of water for a few days, take it out and weigh it again. If there's no appreciable weight gain, it should work okay on your boat. My box exterior (which is a single layer of roving over the hard urethane 2") is currently exposed for most of two sides. I'd thought to put foil on that exterior surface. If I understand you properly, that's counterproductive? Unless the exterior is exposed to a strong radiant heat source, the foil won't help. On to the last: Is that like the lead foam used in noise control, nearly as expensive as heat shield :{)) ? Or is there some other noise abatement of which I'm not aware (there are probably encyclopediea worth of info of which I'm not aware!)? Is this an application where a foil-backed insultion board would help? Yes, it's like the lead & foam sound insulation. I'm using a sound blocking product with a back layer of foam, a layer of some type of semi-rigid plastic, a thicker layer of foam , and faced with shiny Mylar. About an inch and a quarter overall thicknes. I don't remember the brand name but the price was not out of line. My local rubber products retailer carries it in stock. Foil faced insulation in an engine room would work to keep radiant and convected heat away from living spaces. But shiny-faced sound control products with their 'decoupled' layer would do a better overall job. Low emissivity surfaces are very effective at minimizing heat gain from non-contact radiant sources. This includes the sun or even a hot engine block. They are not a solution to other problems. Rusty O Thanks again for your knowledgeable input. L8R Skip and Lydia |
I talked with my brother about the different types or foam board.
The non-faced insulation boards, colored pink, blue, or green, are extruded polystyrene. Because of the nature of the extrusion process the boards have enough structural strength to be handled, cut, and installed without any additional coverings. (The color tells you who made it.) The foil-faced yellow looking foam boards are (poured) expanded polyisocyanurate. The facings applied to these boards are there to provide structural strength during the manufacturing, handling & installation processes. Otherwise they would tend to just break apart at random locations. (It's natural yellow color is difficult to dye to any other color.) White styrofoam board is also available. He also mentioned the foil faced air bubble plastic material. He said the manufactuers of this product have not been able to prove that it has any real 'R' value of any kind. The salesmen even suggested a good use would be to stuff it in your shoes to keep your feet dry. He refuses to distribute this product for these reasons. Rusty O |
Glen, I was trying to say that $1,000 a square foot "vacuum" panels don't stand
up to close scientific scrutny. Buy 'em as is your wish. btw, have you checked just how much cooling power is required to chill a air temp six-pack or two as compared to how much cooling power is required to remove heat passed into the reefer from the outside. hint: the difference in total BTU's of cooling required is almost nothing when comparing R-4 with R-8, and is virtually nothing when comparing R-8 with R-100. It ain't the heat going through the side that gets you, it is the heat you put into the reefer in the form of food. something N. Bruce Nelsen kinda neglects to make mention of. but if you feel you want to hug P. T. Barnum, have at it. Jax, you still don't understand the principle that it is better to keep your mouth shut and have people think you are stupid than opening it and confirming the fact. Most vacuum panels are filled with Instil, an inert open celled silica based foam board from Dow. It has a crush strength of about 50 PSI, well above the 14.7 atmospheric pressure, and an R value at standard pressure of about 5. At 1 milibar vacuum the R value is about 25 and at .1 milibar it is about 30. Glacier Bay uses a special reinforced aerogel material called Nanogel made by Cabot (the Cabosil people) with an R value at standard pressure of about 15. While the bare material is extremely delicate its latticework structure makes it very strong under even compression. At 10 milibar the R value is about 30 and at .1 milibar it is about 50. The curve of vacuum to R value is flatter with Nanogel than with Instil. The obvious advantage is that as the panel loose vacuum the Nanogel will maintain more insulation value. The disadvantage is that Nanogel is much more expensive and harder to work with. The problem with all vacuum insulation is that it is impossible to maintained a high vacuum with a low conductivity flexible membrane. Air molecules will slowly find a way in. Back in the 80s a vacuum panel made of a stainless envelope packed with precipitated silica was popular in refrigerated containers and some high end European refrigerators. It was only effective in large sizes because the steel conducted a lot of heat around the edges. In the mid 90s Toyo and Dupont developed films consisting of several layers of various UHMW plastics coated with a very thin layer of aluminum that made smaller panels practical and easier to fabricate. Those films have been greatly improved over the last 5 years. Around the same time SAES introduced a room temperature getter material to absorb stray gas molecules and packages it in small inexpensive pucks to be inserted in the panels. The net result is that you can reasonably expect 10 to 15 years of R values better than 25 per inch from almost any well constructed vacuum insulation panel. The Glacier Bay Panels will last about 30% longer and have the distinct advangate of maintaining a reasonable level of insulation even with no vacuum. The down side is that they are about twice as expensive. Regardless, marine refrigerators made with vacuum insulation should be built with the need to eventually replace the panels in mind. I am counting on 8 to 10 years and will probably replace them even if they are still reasonably effective. At the present rate of improvement by then the technology will be far better and the prices significantly lower. BTW, you should NOT use two part pour in place foam to fill gaps between vacuum panels. Two part foams produce a lot of heat as they cure. The vacuum panels are so effective that they will trap the heat and possibly damage the plastic film. Moisture curing spray foam like Great Stuff is a lot safer. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "JAXAshby" wrote in message ... Rusty, you take measurements for a living, but are not a design eng. a couple of things to make note of: 1.) "shiney" is shiney from both sides, as far as radiation is concerned. shiney out or shiney in, same same. 2.) shiney on the outside does NOT make for greater (or lesser) conductivity or convectivity. shiney on the outside makes for reflection of the radiant heat **from the outside** (where heat is in a reefer system). shiney on the inside means some of the radiant heat is absorbed on the way through the insulation (makes for warmer insulation) and then is reflected back into the insulation where some of it is also absorbed (making for even warmer insulation). 3. You, Rusty, sound like a shill for N. Bruce Nelsen of Glacier Bay, a man who over the years has made one hell of a lot of claims that don't stand close examination. 4.) "vacuum" panels are not vacuum at all, but rather are panels with a plastic latice inside (to hold the sides of the panel apart) with much, but by no means all, of the air removed. (air pressure is 14.7 pounds PER SQUARE INCH, so a 1 square foot panel encasing a true vacuum would have over 2,000 pounds pressure trying to collapse the sides. |
Skip, rusty is a temperature measurer NOT a design engineer. If rusty were
correct, all that pink insulation you see in Home Cheapo would not have the shiny foil backing it does. Maybe rusty has never seen insulation in HD or any place else? Rusty, thank you so much for your informed and concise presentation. It's very complete, and answers most of my questions, but generates a couple of others. Please indulge me? And, since you're spamtrapped, I can't ask you directly, but may I quote you in the various mailing lists to which I posed the same question(s)? A reflective barrier can greatly reduce the heat gain to a cool object from infrared radiation. The question is, where to put it? (exposition clipped) The bottom line: Most heat gain to a refrigerated box is through convection and conduction, not infrared radiation. There is no free ride and reflective foils will not noticeably improve the insulating qualities of the typical boat ice box. So, effectively, without a vacuum (or, at least, a free-space non-touching environment), the addtion of aluminum foil merely acts to accelerate (aluminum being an excellent heat conductor) heat transfer? Thus, for example, the foil-faced building insulation products are no better than the level of vacuum behind them? I'd been migrating to the thought of layering heavy foil between the highest R-value foam I could find, and then doing a heat-sealed vapor barrier wrap, evacuated to the best of my ability. However, your comments suggest that's a waste of time. I *think* I understand you to say that foil is counterproductive if not faced with a vacuum. If so, from that, if I'm not going to spring for the vacuum panels, simple block foam, encapsulated to prevent moisture, is the best? My box exterior (which is a single layer of roving over the hard urethane 2") is currently exposed for most of two sides. I'd thought to put foil on that exterior surface. If I understand you properly, that's counterproductive? On to the last: I can think of one place a reflective foil might help. If you had a freezer or refrigerator, with adequate vacuum or foam insulation, that had one side facing the inside of you engine room then foil on that surface facing the engine would reduce infrared heat gain to the box when running the engine. But that can also be covered with Mylar faced noise control foam with even better results. Is that like the lead foam used in noise control, nearly as expensive as heat shield :{)) ? Or is there some other noise abatement of which I'm not aware (there are probably encyclopediea worth of info of which I'm not aware!)? Is this an application where a foil-backed insultion board would help? Thanks again for your knowledgeable input. L8R Skip and Lydia Rusty O -- Morgan 461 #2 SV Flying Pig http://tinyurl.com/384p2 "Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover." - Mark Twain |
btw, commercial ice boxes always have an shiny ss liner and/or outside. It
works, at least in the commercial reefer environment. |
s that like the lead foam used in noise control, nearly as expensive as
heat shield :{)) ? Or is there some other noise abatement of which I'm not aware sound attenuation requires _heavy_ lead or other _heavy- material. |
|
Actually $1,000 of vacuum panels will just about completely insulate my 4.5
cu. ft. freezer to R50 and ajoining 7 cu. ft. fridge to R28. (Plus another R12 for the iso sheets that I am wrapping the panels in.) Why think six packs??? I am thinking in the case range. A case of brew takes 750 BTUs to get it from dock side 80F to whistle wetting 40F. That was built into my calculations from the start along with another 800 BTUs for opening and closing the box to get to the beer. No insulation is going to help that. But the base heat gain without adding anything or opening at an ambient temperature of 95F with vacuum insulation will be about 2,300 BTUs. Total load right at 3,800 BTUs worst case. That is about 8 hours and 70 amp hours on a BD50F compressor. I don't have room for more than 2" of insulation so foam would increase the heat load to about 6,400 BTUs plus the 1,550 BTU beer load.. That would be 14 hours and 110 amp hours on a BD50. To add enough foam insulation to equal the vacuum panels would increase the volume of my box by about 40 cu. ft. Considering that the interior volume of my boat will cost about $60/ cu.ft. not counting my labor, saving 40 cu. ft. is worth more than twice what the vacuum insulation will cost. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "JAXAshby" wrote in message ... Glen, I was trying to say that $1,000 a square foot "vacuum" panels don't stand up to close scientific scrutny. Buy 'em as is your wish. btw, have you checked just how much cooling power is required to chill a air temp six-pack or two as compared to how much cooling power is required to remove heat passed into the reefer from the outside. hint: the difference in total BTU's of cooling required is almost nothing when comparing R-4 with R-8, and is virtually nothing when comparing R-8 with R-100. It ain't the heat going through the side that gets you, it is the heat you put into the reefer in the form of food. something N. Bruce Nelsen kinda neglects to make mention of. but if you feel you want to hug P. T. Barnum, have at it. Jax, you still don't understand the principle that it is better to keep your mouth shut and have people think you are stupid than opening it and confirming the fact. Most vacuum panels are filled with Instil, an inert open celled silica based foam board from Dow. It has a crush strength of about 50 PSI, well above the 14.7 atmospheric pressure, and an R value at standard pressure of about 5. At 1 milibar vacuum the R value is about 25 and at .1 milibar it is about 30. Glacier Bay uses a special reinforced aerogel material called Nanogel made by Cabot (the Cabosil people) with an R value at standard pressure of about 15. While the bare material is extremely delicate its latticework structure makes it very strong under even compression. At 10 milibar the R value is about 30 and at .1 milibar it is about 50. The curve of vacuum to R value is flatter with Nanogel than with Instil. The obvious advantage is that as the panel loose vacuum the Nanogel will maintain more insulation value. The disadvantage is that Nanogel is much more expensive and harder to work with. The problem with all vacuum insulation is that it is impossible to maintained a high vacuum with a low conductivity flexible membrane. Air molecules will slowly find a way in. Back in the 80s a vacuum panel made of a stainless envelope packed with precipitated silica was popular in refrigerated containers and some high end European refrigerators. It was only effective in large sizes because the steel conducted a lot of heat around the edges. In the mid 90s Toyo and Dupont developed films consisting of several layers of various UHMW plastics coated with a very thin layer of aluminum that made smaller panels practical and easier to fabricate. Those films have been greatly improved over the last 5 years. Around the same time SAES introduced a room temperature getter material to absorb stray gas molecules and packages it in small inexpensive pucks to be inserted in the panels. The net result is that you can reasonably expect 10 to 15 years of R values better than 25 per inch from almost any well constructed vacuum insulation panel. The Glacier Bay Panels will last about 30% longer and have the distinct advangate of maintaining a reasonable level of insulation even with no vacuum. The down side is that they are about twice as expensive. Regardless, marine refrigerators made with vacuum insulation should be built with the need to eventually replace the panels in mind. I am counting on 8 to 10 years and will probably replace them even if they are still reasonably effective. At the present rate of improvement by then the technology will be far better and the prices significantly lower. BTW, you should NOT use two part pour in place foam to fill gaps between vacuum panels. Two part foams produce a lot of heat as they cure. The vacuum panels are so effective that they will trap the heat and possibly damage the plastic film. Moisture curing spray foam like Great Stuff is a lot safer. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "JAXAshby" wrote in message ... Rusty, you take measurements for a living, but are not a design eng. a couple of things to make note of: 1.) "shiney" is shiney from both sides, as far as radiation is concerned. shiney out or shiney in, same same. 2.) shiney on the outside does NOT make for greater (or lesser) conductivity or convectivity. shiney on the outside makes for reflection of the radiant heat **from the outside** (where heat is in a reefer system). shiney on the inside means some of the radiant heat is absorbed on the way through the insulation (makes for warmer insulation) and then is reflected back into the insulation where some of it is also absorbed (making for even warmer insulation). 3. You, Rusty, sound like a shill for N. Bruce Nelsen of Glacier Bay, a man who over the years has made one hell of a lot of claims that don't stand close examination. 4.) "vacuum" panels are not vacuum at all, but rather are panels with a plastic latice inside (to hold the sides of the panel apart) with much, but by no means all, of the air removed. (air pressure is 14.7 pounds PER SQUARE INCH, so a 1 square foot panel encasing a true vacuum would have over 2,000 pounds pressure trying to collapse the sides. |
Depends on what you mean by commercial. Commercial freezer rooms usually
have galvanized sheet steel because it is rugged, cheap and can take abuse. Commercial refrigerators have stainless interiors because it is rugged and easier to clean. Neither have anything to do with the insulation. The insulation is provided by 4 to 8" of urethane or in more modern boxes isocyanurate foam. Marine refrigerators used to have stainless liners because it was rugged, easy to clean and easy to fabricate in custom shapes. Now they have off white injection molded polystyrene liners because it is rugged, easy to clean, and cheap. They also add minimally to the insulation value because they don't conduct as well as steel. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "JAXAshby" wrote in message ... btw, commercial ice boxes always have an shiny ss liner and/or outside. It works, at least in the commercial reefer environment. |
Glenn, one BTU = one pound of water raised/lowered one degree. therefore, a
case of 24 bottles of 16 ounces each lowered 40 degrees takes 960 BTU's removal. That is about 6 hours net effective running time for a standard marine reefer using about 5 amps. now, add in a couple of soda's, five pounds of fish, some hamburger, some cheese, some milk, etc. now freeze some of that. keep in mind that each pound of water lowered from 40 to 32 takes another 8 Bthu's, changing from 32 water to 32 ice takes 144 Btu's, lowering from 32 ice to 10* ice takes another 22 Btu's. keep in mind that 10* won't keep ice cream solid. |
careful, Glenn, the "heat removal" figure you see listed for marine reefers are
a.) TOTAL heat removal *****including****** the heat added by the compressor (in other words NOT the heat removed from the ice box), and b.) **IF** you believe the cooling figures given you ALSO believe you can make 26 pounds of ice per 8 hours and use just 70 amps to do it. 75 pounds of ice per day?????????? On a total of 9 amps per hour????????? those are the figures you quote below. Really. Sound like you have a cruising income source ready at hand. just buy a Briggs and Stratton engine (HarborFreight.com) for a couple hundred, and a used alternotor from an auto junk yard for fifty bucks and start churning ice you can sell to other cruiser. Sell them the canvas bags to carry all that ice back to their boats and make some extra money as well. N. Bruce Nelsen did a number on ya, Glenn. Sorry. Actually $1,000 of vacuum panels will just about completely insulate my 4.5 cu. ft. freezer to R50 and ajoining 7 cu. ft. fridge to R28. (Plus another R12 for the iso sheets that I am wrapping the panels in.) Why think six packs??? I am thinking in the case range. A case of brew takes 750 BTUs to get it from dock side 80F to whistle wetting 40F. That was built into my calculations from the start along with another 800 BTUs for opening and closing the box to get to the beer. No insulation is going to help that. But the base heat gain without adding anything or opening at an ambient temperature of 95F with vacuum insulation will be about 2,300 BTUs. Total load right at 3,800 BTUs worst case. That is about 8 hours and 70 amp hours on a BD50F compressor. I don't have room for more than 2" of insulation so foam would increase the heat load to about 6,400 BTUs plus the 1,550 BTU beer load.. That would be 14 hours and 110 amp hours on a BD50. To add enough foam insulation to equal the vacuum panels would increase the volume of my box by about 40 cu. ft. Considering that the interior volume of my boat will cost about $60/ cu.ft. not counting my labor, saving 40 cu. ft. is worth more than twice what the vacuum insulation will cost. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "JAXAshby" wrote in message ... Glen, I was trying to say that $1,000 a square foot "vacuum" panels don't stand up to close scientific scrutny. Buy 'em as is your wish. btw, have you checked just how much cooling power is required to chill a air temp six-pack or two as compared to how much cooling power is required to remove heat passed into the reefer from the outside. hint: the difference in total BTU's of cooling required is almost nothing when comparing R-4 with R-8, and is virtually nothing when comparing R-8 with R-100. It ain't the heat going through the side that gets you, it is the heat you put into the reefer in the form of food. something N. Bruce Nelsen kinda neglects to make mention of. but if you feel you want to hug P. T. Barnum, have at it. Jax, you still don't understand the principle that it is better to keep your mouth shut and have people think you are stupid than opening it and confirming the fact. Most vacuum panels are filled with Instil, an inert open celled silica based foam board from Dow. It has a crush strength of about 50 PSI, well above the 14.7 atmospheric pressure, and an R value at standard pressure of about 5. At 1 milibar vacuum the R value is about 25 and at .1 milibar it is about 30. Glacier Bay uses a special reinforced aerogel material called Nanogel made by Cabot (the Cabosil people) with an R value at standard pressure of about 15. While the bare material is extremely delicate its latticework structure makes it very strong under even compression. At 10 milibar the R value is about 30 and at .1 milibar it is about 50. The curve of vacuum to R value is flatter with Nanogel than with Instil. The obvious advantage is that as the panel loose vacuum the Nanogel will maintain more insulation value. The disadvantage is that Nanogel is much more expensive and harder to work with. The problem with all vacuum insulation is that it is impossible to maintained a high vacuum with a low conductivity flexible membrane. Air molecules will slowly find a way in. Back in the 80s a vacuum panel made of a stainless envelope packed with precipitated silica was popular in refrigerated containers and some high end European refrigerators. It was only effective in large sizes because the steel conducted a lot of heat around the edges. In the mid 90s Toyo and Dupont developed films consisting of several layers of various UHMW plastics coated with a very thin layer of aluminum that made smaller panels practical and easier to fabricate. Those films have been greatly improved over the last 5 years. Around the same time SAES introduced a room temperature getter material to absorb stray gas molecules and packages it in small inexpensive pucks to be inserted in the panels. The net result is that you can reasonably expect 10 to 15 years of R values better than 25 per inch from almost any well constructed vacuum insulation panel. The Glacier Bay Panels will last about 30% longer and have the distinct advangate of maintaining a reasonable level of insulation even with no vacuum. The down side is that they are about twice as expensive. Regardless, marine refrigerators made with vacuum insulation should be built with the need to eventually replace the panels in mind. I am counting on 8 to 10 years and will probably replace them even if they are still reasonably effective. At the present rate of improvement by then the technology will be far better and the prices significantly lower. BTW, you should NOT use two part pour in place foam to fill gaps between vacuum panels. Two part foams produce a lot of heat as they cure. The vacuum panels are so effective that they will trap the heat and possibly damage the plastic film. Moisture curing spray foam like Great Stuff is a lot safer. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "JAXAshby" wrote in message ... Rusty, you take measurements for a living, but are not a design eng. a couple of things to make note of: 1.) "shiney" is shiney from both sides, as far as radiation is concerned. shiney out or shiney in, same same. 2.) shiney on the outside does NOT make for greater (or lesser) conductivity or convectivity. shiney on the outside makes for reflection of the radiant heat **from the outside** (where heat is in a reefer system). shiney on the inside means some of the radiant heat is absorbed on the way through the insulation (makes for warmer insulation) and then is reflected back into the insulation where some of it is also absorbed (making for even warmer insulation). 3. You, Rusty, sound like a shill for N. Bruce Nelsen of Glacier Bay, a man who over the years has made one hell of a lot of claims that don't stand close examination. 4.) "vacuum" panels are not vacuum at all, but rather are panels with a plastic latice inside (to hold the sides of the panel apart) with much, but by no means all, of the air removed. (air pressure is 14.7 pounds PER SQUARE INCH, so a 1 square foot panel encasing a true vacuum would have over 2,000 pounds pressure trying to collapse the sides. |
people who want refrigeration are willing to convince themselves of anything.
brokers in the Caribbean use the term "ice assisted" in the context of commenting on refrigeration in any boat they have for sale. There is a reason they use that term. Depends on what you mean by commercial. Commercial freezer rooms usually have galvanized sheet steel because it is rugged, cheap and can take abuse. Commercial refrigerators have stainless interiors because it is rugged and easier to clean. Neither have anything to do with the insulation. The insulation is provided by 4 to 8" of urethane or in more modern boxes isocyanurate foam. Marine refrigerators used to have stainless liners because it was rugged, easy to clean and easy to fabricate in custom shapes. Now they have off white injection molded polystyrene liners because it is rugged, easy to clean, and cheap. They also add minimally to the insulation value because they don't conduct as well as steel. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "JAXAshby" wrote in message ... btw, commercial ice boxes always have an shiny ss liner and/or outside. It works, at least in the commercial reefer environment. |
Jax,
This is going to be my last responce because it is pretty obvious that you have no idea what you are talking about, twist my statements and make rediculous assumptions. First, A normal can of beer is 12 ounces. Not 16. Tall boys are no good on boats because they get warm before you can drink them all. Second, I am allowing 6 beers a day for a crew of 4. That is more than most prudent skippers will allow. Especially with hard liquor sundowners and night caps. :-) BTW, that 800 BTU buffer includes 400 BTUs for making enough ice for those cocktails and 90% of the frozen provisions will be frozen before they get to the boat. Now before you go saying that two pounds of ice is not enough consider that a 8 oz cocktail glass will hold about .2 pounds of ice so that is enough for 10 drinks. Third, I should have mentioned that the design temperature used to calculate my heat gain for the box is 40F and the freezer is 0F. That is good enough to keep ice cream. Besides, with my belt size I don't need much ice cream. OTOH, I don't wear speedos. ;-) Now, as to refrigeration performance figures. We went through this two years ago and I am not going to get sucked into another interminable debate so I will leave it with the following statement which I have verified with the chairman of the ASHRAE standards committee.. Performance specifications, be they COP, EER or ASHRAE capacity are based the NET heat removed. It does NOT include heat generated in the process. You are almost correct on the 75 pounds of ice assuming the system is set up do do nothing but freeze ice with a constant supply of water moving across the plates so that the heat is removed efficiently. But it is more like 90 pounds. A BD50F at 3,000 RPM and a plate temperature of -5F has an ASHRAE capacity rating of 166 Watts. Times 3.413 we get 566 BTUs/hour or about 13,000 BTUs/day. The current draw is 7.4 amps or 177 amp hours. That is a COP of 1.87 and an EER of about 6.3. That is about the same as a modern 110VAC hermetic compressor. You make the assumption that all compressor manufacturers are lying about theyr specifications. If that were true no refrigeration designer would ever be able to build a refrigerator that would work the way it was supposed to. . --. Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com |
Rusty O wrote:
He also mentioned the foil faced air bubble plastic material. He said the manufactuers of this product have not been able to prove that it has any real 'R' value of any kind. The salesmen even suggested a good use would be to stuff it in your shoes to keep your feet dry. He refuses to distribute this product for these reasons. The "foil faced air bubble products Do work in some applications. I have a 200x65 ft building with a shingle roof and the bubble wrap product underneath it, and it DOES keep the radiant heat from the sun off of the roof sheathing (the temp on the inside of the sheathing is about 40deg f below a neighboring roof without it. Having said that, it probably wouldn't help a fridge unless you set it in the sun. Rusty O -- ""War is an ugly thing, but not the ugliest of things. The decayed and degraded state of moral and patriotic feeling which thinks that nothing is worth war is much worse." John Stewart Mill I strongly urge everyone reading this to check out WWW.anysoldier.us, and support our troops with a letter, a package or a donation. |
Glenn, you want the reefer and you are going to pay whatever the price is. Lie
to yourself as to what that price is all you want, for you want the reefer and you are going to pay whatever the price is. Glenn, in the corporate world of ordinary finance you would have been sent to the loading dock to see if it is raining outside. Glenn, you want the reefer and you are going to pay whatever the price is. Ignore the realities, because you want the reefer. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. Glenn, you want the reefer and you are going to pay whatever the price is. From: "Glenn Ashmore" Date: 11/24/2004 10:10 AM Eastern Standard Time Message-id: dv1pd.3558$wa1.2148@lakeread04 Jax, This is going to be my last responce because it is pretty obvious that you have no idea what you are talking about, twist my statements and make rediculous assumptions. First, A normal can of beer is 12 ounces. Not 16. Tall boys are no good on boats because they get warm before you can drink them all. Second, I am allowing 6 beers a day for a crew of 4. That is more than most prudent skippers will allow. Especially with hard liquor sundowners and night caps. :-) BTW, that 800 BTU buffer includes 400 BTUs for making enough ice for those cocktails and 90% of the frozen provisions will be frozen before they get to the boat. Now before you go saying that two pounds of ice is not enough consider that a 8 oz cocktail glass will hold about .2 pounds of ice so that is enough for 10 drinks. Third, I should have mentioned that the design temperature used to calculate my heat gain for the box is 40F and the freezer is 0F. That is good enough to keep ice cream. Besides, with my belt size I don't need much ice cream. OTOH, I don't wear speedos. ;-) Now, as to refrigeration performance figures. We went through this two years ago and I am not going to get sucked into another interminable debate so I will leave it with the following statement which I have verified with the chairman of the ASHRAE standards committee.. Performance specifications, be they COP, EER or ASHRAE capacity are based the NET heat removed. It does NOT include heat generated in the process. You are almost correct on the 75 pounds of ice assuming the system is set up do do nothing but freeze ice with a constant supply of water moving across the plates so that the heat is removed efficiently. But it is more like 90 pounds. A BD50F at 3,000 RPM and a plate temperature of -5F has an ASHRAE capacity rating of 166 Watts. Times 3.413 we get 566 BTUs/hour or about 13,000 BTUs/day. The current draw is 7.4 amps or 177 amp hours. That is a COP of 1.87 and an EER of about 6.3. That is about the same as a modern 110VAC hermetic compressor. You make the assumption that all compressor manufacturers are lying about theyr specifications. If that were true no refrigeration designer would ever be able to build a refrigerator that would work the way it was supposed to. . --. Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com |
You are almost correct on the 75 pounds of ice...
But it is more like 90 pounds. Glenn, have you EVER actually talked to --------------- ANY ------------------------------ cruiser even in his wildest dreams __claims___ ninety frickin' pounds of ice per day? How about making a single pound of ice in less than 4 hours? 8 hours? 16 hours? 24 hours? dream on, Glenn, because you want the reefer and you will pay whatever the cost is. Whatever the cost is. |
Jax, you still don't have a clue.
By now. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "JAXAshby" wrote in message ... You are almost correct on the 75 pounds of ice... But it is more like 90 pounds. Glenn, have you EVER actually talked to --------------- ANY ------------------------------ cruiser even in his wildest dreams __claims___ ninety frickin' pounds of ice per day? How about making a single pound of ice in less than 4 hours? 8 hours? 16 hours? 24 hours? dream on, Glenn, because you want the reefer and you will pay whatever the cost is. Whatever the cost is. |
maybe, maybe not. However, I do understand cost accounting, a term you never
heard of, let alone understand. I also know what a BTU is, and know there is no frickin' way in hell *you* are going to produce a pound of ice in 18 minutes in that expensive abortion you are putting together. glenn, you want the reefer whatever the cost is. Just admit it you don't care if the cost is $10 a day or $30 a day. You want, therefore you spend. Hate to tell you this, Glenn, but a cold brew in a 5 star shoreside bar is cheaper than out of your reefer. but you want the reefer whatever the cost is. complain all you want about my knowledege, glenn, but *you* would get tossed from a corporate financial meeting before the first cup of coffee cooled to drinking temp. you want the reefer whatever the cost is. enjoy, but stop claiming your reefer diety is the God of The Universe. you want the reefer whatever the cost is. just admit it and go on. From: "Glenn Ashmore" Date: 11/24/2004 8:10 PM Eastern Standard Time Message-id: kiapd.3605$wa1.1047@lakeread04 Jax, you still don't have a clue. By now. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "JAXAshby" wrote in message ... You are almost correct on the 75 pounds of ice... But it is more like 90 pounds. Glenn, have you EVER actually talked to --------------- ANY ------------------------------ cruiser even in his wildest dreams __claims___ ninety frickin' pounds of ice per day? How about making a single pound of ice in less than 4 hours? 8 hours? 16 hours? 24 hours? dream on, Glenn, because you want the reefer and you will pay whatever the cost is. Whatever the cost is. |
Jax, you still don't have a clue.
Really, Glenn? But I am not the one with $18,000 dollars stuck into a reefer system that requires me to run the engine for three hours a day. |
That is so far off that I just have to reply. I am not doing this as a
rebuttal to your asinine comments but for the benefit of those lurkers who might be interested in the thought process. The TOTAL cost of my refrigeration system is a little under $4K including the vacuum insulation, separate keel cooled compressors for the freezer and refrigerator, custom made double sealed lids with solid surface tops and the materials for the cabinet work. Under the worst case load it will consume about 90 amp hours. My alternator produces 270 amps and the battery bank is a little over 800 amp hours so the average charge time required for refrigeration will be about 20 minutes assuming no output from the solar panels. If you want to consider ALL the cost of the batteries, alternators, 3 stage regulator and solar panels as exclusively used for refrigeration add another $3K. But that is not really fair because refrigeration is only 1/3 of my energy budget. A fair figure for the total cost of my refrigeration system is about $5K. If I were really considering this project on a cost accounting basis I would not own a boat in the first place but money in excess of that required to survive comfortably is useless unless you can have some fun with it. But lets give a little cost accounting a try and see what happens. To estimate the real cost of the system we need to make some assumptions. First we amortize the capital costs. Let's assume over an economic life of 10 years at the end of which an additional $3,000 will be required to refit the mechanical parts and vacuum panels. Assuming an average use of 120 days a year that works out to about $4.40/day including opportunity cost of the capital at 6%. Now let's consider the operating costs. Two unshaded 150 watt solar panels in the tropics should be expected to optimally produce about 160 amp hours of charge. But things are never optimal so to be conservative we will assume only 25% or 40 amp hours (that is average. Not every day.) so the engine must provide the remaining 50 amp hours or about 12 minutes of run time. From a separate calculation of engine expenses that includes capital costs, overhauls, oil, general maintenance and fuel at $4/gallon over the service live, that is about $1.20 ignoring the 5 gallons of water that will be produced at the same time and the value of any forward progress the boat makes.. For good measure, lets throw in another $360/year reserve for repairs. So the total cost of the system can be conservatively estimated at about $6.60/day. Obviously not as good as the $.60 to $1.00 a day that a home refrigerator cost but about the middle of the cost range for marine refrigeration. For comparison, a simple $300 foam insulated ice box of similar capacity will require about 3,600 BTUs a day or 25 pounds of ice. The current price of a 10 lb. bag of ice in the Bahamas and Virgin Islands is $2.50 and considerably higher in Martinique, St. Martin and other Caribbean islands. That works out to about $6.25 a day with no freezer and not including the value of lost personal time constantly having to get more ice. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "JAXAshby" wrote in message ... Jax, you still don't have a clue. Really, Glenn? But I am not the one with $18,000 dollars stuck into a reefer system that requires me to run the engine for three hours a day. |
like I said, Glenn, in the world of corporate finance you would be asked to go
to the loading dock to see if it is raining outside. You grasp of the principles of cost accounting is too weak to even be considered minimal. you want the reefer at whatever cost, and you will force fit the cost figures into your planned budget no matter what the reality. "20 frickin' minutes a day engine runtime" to maintain your reefer cool (not cold, but cool)? You have to be kidding. Even those who are "out there" are CLAIMING 30 minutes to an hour **twice** a day. And just a side note, Glenn, the cruisers anchored around those "I gotta have ice cubes in my drinks" reefer boats claim the assholes run their engines far more like a hour and a half in the morning, then start their engines in the afternoon and go ashore (for a couple of cold, not cool, ones) for 2-1/2 to 3 hours. btw, I notice you _claim_ that your 90 amps per day for your planned reefer is only 1/3 of your total energy budget. In other words, you are currently budgeted for nearly ***three frickin' hundred amps*** PER DAY!! That is you _budget_, which if you are like most people is about one half or less than what you will really use per day. Glenn, you want your reefer and will get it whatever the cost. Frankly, I feel cold, not cool, iced drinks ashore is one hell of a lot cheaper. From: "Glenn Ashmore" Date: 11/24/2004 10:50 PM Eastern Standard Time Message-id: 7Ecpd.3629$wa1.1178@lakeread04 That is so far off that I just have to reply. I am not doing this as a rebuttal to your asinine comments but for the benefit of those lurkers who might be interested in the thought process. The TOTAL cost of my refrigeration system is a little under $4K including the vacuum insulation, separate keel cooled compressors for the freezer and refrigerator, custom made double sealed lids with solid surface tops and the materials for the cabinet work. Under the worst case load it will consume about 90 amp hours. My alternator produces 270 amps and the battery bank is a little over 800 amp hours so the average charge time required for refrigeration will be about 20 minutes assuming no output from the solar panels. If you want to consider ALL the cost of the batteries, alternators, 3 stage regulator and solar panels as exclusively used for refrigeration add another $3K. But that is not really fair because refrigeration is only 1/3 of my energy budget. A fair figure for the total cost of my refrigeration system is about $5K. If I were really considering this project on a cost accounting basis I would not own a boat in the first place but money in excess of that required to survive comfortably is useless unless you can have some fun with it. But lets give a little cost accounting a try and see what happens. To estimate the real cost of the system we need to make some assumptions. First we amortize the capital costs. Let's assume over an economic life of 10 years at the end of which an additional $3,000 will be required to refit the mechanical parts and vacuum panels. Assuming an average use of 120 days a year that works out to about $4.40/day including opportunity cost of the capital at 6%. Now let's consider the operating costs. Two unshaded 150 watt solar panels in the tropics should be expected to optimally produce about 160 amp hours of charge. But things are never optimal so to be conservative we will assume only 25% or 40 amp hours (that is average. Not every day.) so the engine must provide the remaining 50 amp hours or about 12 minutes of run time. From a separate calculation of engine expenses that includes capital costs, overhauls, oil, general maintenance and fuel at $4/gallon over the service live, that is about $1.20 ignoring the 5 gallons of water that will be produced at the same time and the value of any forward progress the boat makes.. For good measure, lets throw in another $360/year reserve for repairs. So the total cost of the system can be conservatively estimated at about $6.60/day. Obviously not as good as the $.60 to $1.00 a day that a home refrigerator cost but about the middle of the cost range for marine refrigeration. For comparison, a simple $300 foam insulated ice box of similar capacity will require about 3,600 BTUs a day or 25 pounds of ice. The current price of a 10 lb. bag of ice in the Bahamas and Virgin Islands is $2.50 and considerably higher in Martinique, St. Martin and other Caribbean islands. That works out to about $6.25 a day with no freezer and not including the value of lost personal time constantly having to get more ice. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "JAXAshby" wrote in message ... Jax, you still don't have a clue. Really, Glenn? But I am not the one with $18,000 dollars stuck into a reefer system that requires me to run the engine for three hours a day. |
Jax says:
like I said, Glenn, in the world of corporate finance you would be asked to go to the loading dock to see if it is raining outside. Which may be why he isn't in it. God knows it would bore me to tears, and I couldn't be less interested in it. you are currently budgeted for nearly ***three frickin' hundred amps*** PER DAY!! I'd have thought with your penchant for being able to quote definitions for units so readly that you would have realised that it's AMP-HOURS, not amps. Frankly, I feel cold, not cool, iced drinks ashore is one hell of a lot cheaper. That probably would suit Glenn very well, as it keeps you (and yahoos like you) out of the harbour more. Steve |
like I said, Glenn, in the world of corporate finance you would be asked to
go to the loading dock to see if it is raining outside. Which may be why he isn't in it. God knows it would bore me to tears, and I couldn't be less interested in it. which is solid reason neither of you should open your mouths as to true costs. You don't know squat about the subject and you are proud of your ignorance. Glenn, however, might be forgiven a bit while you steve can not. Glenn wants that reefer whatever the price. |
Jax says:
You don't know squat about the subject and you are proud of your ignorance. Kinda like you and boats? |
JAXAshby wrote:
like I said, Glenn, in the world of corporate finance you would be asked to go to the loading dock to see if it is raining outside. Which may be why he isn't in it. God knows it would bore me to tears, and I couldn't be less interested in it. which is solid reason neither of you should open your mouths as to true costs. You don't know squat about the subject and you are proud of your ignorance. Glenn, however, might be forgiven a bit while you steve can not. Glenn wants that reefer whatever the price. And you are the Authority? |
Rick, cost accounting was a required skill set in my chosen career.
From: Rick Date: 11/25/2004 3:46 PM Eastern Standard Time Message-id: JAXAshby wrote: like I said, Glenn, in the world of corporate finance you would be asked to go to the loading dock to see if it is raining outside. Which may be why he isn't in it. God knows it would bore me to tears, and I couldn't be less interested in it. which is solid reason neither of you should open your mouths as to true costs. You don't know squat about the subject and you are proud of your ignorance. Glenn, however, might be forgiven a bit while you steve can not. Glenn wants that reefer whatever the price. And you are the Authority? |
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