rusty? have you EVER seen a commercial reefer unit? if so, why did you not
notice all that shiny stuff around it? maybe you might want to ask commercial
fishermen just how their reefers are constructed.

From: "Rusty O"
Date: 11/23/2004 3:16 PM Eastern Standard Time
Message-id: t

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

thank you, mr temp measurer for your anecdotes posted as scientific fact. now,
please finish your coffee break and get back to work.

From: "Rusty O"
Date: 11/23/2004 6:45 PM Eastern Standard Time
Message-id: . net

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

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.

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.

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.

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.

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.