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.

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

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

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.