Heavy Metal
Heavy Metal
(OP)
I have a very interesting wall construction I am dealing with, and wanted to see if the group agrees with my assessment. I have a wall construction that is 3/8" steel on the outside, with 6x6x1/4" tubes every 24" on center with a 14 ga liner on the inside, in-between each column is R-13 insulation. At each one of those tubes I can't see any reason that during the winter the inside wall condition wouldn't be the same as the outside air, and during the summer the outside wall would be the same as the inside condition. This issue, given the coastal climate these buildings would be in, would cause condensation on the inside during the winter, and condensation on the outside in the summer.





RE: Heavy Metal
14 ga liner?
There will certainly be a fair bit of heat transfer here going on, but the temp won't be identical - 3" of metal temp needs to go via a 1/4" steel plate 6" deep.
what is this - a container?
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RE: Heavy Metal
By tubes I mean 6x6x1/4" steel square tubing.
In the box is electrical switchgear.
It is 14 gauge steel liner.
I agree it seems that way, but it would actually be 1/2" of steel plate (because there are two sides to the box) and then the other 5.5" is dead air space, so no insulating value there either...
RE: Heavy Metal
It really brings to question what is driving the heat transfer through the wall.
My thoughts and experience tells me the mass and temperature of the ambient air.
In which case with cold walls in winter; condensation on the inside during winter would be a potential issue.
In summer however, the wall will tend to be warmer and condensation on the outside would not be an issue.
RE: Heavy Metal
RE: Heavy Metal
B.E.
You are judged not by what you know, but by what you can do.
RE: Heavy Metal
RE: Heavy Metal
I did some calcs once for a wall with R-19 insulation between metal studs, the overall U-value of the wall went down to about 0.091 (R-11). Unless you add insulation like Berkshire said, you'll be lucky if the overall U-value of the wall you described is 0.2 (R-5).
RE: Heavy Metal
RE: Heavy Metal
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RE: Heavy Metal
Best to you,
Goober Dave
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RE: Heavy Metal
In this case, assuming any ventilation comes from outdoors the dew point of the air in the space will match the dew point of the OA. Therefore the air will not condense on either side in the winter.
RE: Heavy Metal
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RE: Heavy Metal
I would expect electrical gear only needs to be maintained at a reasonably hot condition, perhaps suitable for techs working inside, high above any ambient wet bulbs? I guess I'm not understanding why you are insulating this at all. What temperature are you maintaining in the room? Most electrical rooms are left to rise to 80-90 degF or more. If you are at similar temps inside, heat flow thru the walls reduces your cooling loads, except perhaps in summer. I don't see how your inside wall condition is ever going to be the same as the outside ambient condition in the winter.
RE: Heavy Metal
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RE: Heavy Metal
Of course this may differ based on your location, but I thought I would bring it up.
Alternatively, why don't you put the batteries or other temperature sensitive components is a separate, small insulated room? That way you would not have to worry about air conditioning your blast proof switch gear building? That might eliminate the possibility of exterior condensation during the summer.
RE: Heavy Metal
We wanted to separate them out, but there is not space on the site to grow the building, or add new buildings. It is very tight.