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Manufacturer:
The Celotex Corporation
Address: 4010 Boy Scout Blvd., Tampa, FL 33607
Phone: (813) 873-1700
Web Site: www.celotex.com
Product Name:
Thermax
Insulation Classification: Foam Insulation
Thickness As Tested: 1.00"
Claimed "R" Value: 7.2
Actual "R" Value (at product thickness): 6.35
Equivalent "R" Value (per inch): 6.35
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Product Overview
The Celotex Corporation manufacturers a range of products for the building
industry. Among these are a line of aluminum foil covered polyisocyanurate-based
thermal insulation including Thermax. In this case, the aluminum foil serves
primarily as a moisture barrier though some radiant benefits are also claimed. Such
a barrier is required for polyisocyanurate foams since they are among the most hygroscopic
(moisture absorbing) insulating foams available. The aluminum foil covering is a
satisfactory barrier for most land-based installations but can actually contribute to
moisture saturation in the marine environment.
Limited Radiant Heat Benefit
As previously mentioned, Thermax is covered with aluminum foil one both sides. While
this serves primarily as a moisture barrier, the company does claim some additional
limited benefit from its "radiant heat reflective" qualities. It is
interesting to note that Celotex claims an additional R-2.8 will be achieved if the
insulation is used in a manner that takes advantage of its reflective properties.
This, they say, would be achieved if the insulation were installed so as to reflect the
heat into a surrounding air space. While many would dispute even the R-2.8 rating,
Celotex should be congratulated for not making the kind of outrageous claims so common
with reflective insulation manufacturers. It's not that the aluminum foil on Thermax
is any less "reflective" of radiant heat than is the aluminum foil used in Heat
Shield, Reflectix, The Insulator, etc., it is just that Celotex is intentionally (and
correctly) downplaying the significance of such foils.
Test Conclusion
Thermax is an excellent insulation for marine refrigerator applications if the proper
precautions can be taken to protect it from moisture saturation. In our experience,
it is mandatory that the insulation be totally encapsulated (in fiberglass and resin or
polysulfide rubber) in such a manner that it is hermetically sealed against any possible
air intrusion. This can only be accomplished if the ice box can be constructed, and
the insulation sealed, prior to being mounted in the final position. If space and
working conditions permit you to use this construction method, Thermax can be an excellent
choice in foam insulation.
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