Staple down radiant ceilings
rhl_
| Posted in Mechanicals on
I’ve been thinking over the prospect of adding some radiant ceiling loops into my second floor ceiling via the floor of the unconditioned attic. This is in Zone 4A.
My first concern would be freezing risk of these loops.
How much insulation do I need to obviate myself of this risk?
Also, would one simply add ordinary extruded aluminum heat plates?
Also, i was planning on dense packing my attic floors. Now i would need a small air gap between the piping/plates and the insulation, in order to not prevent the radiant from working? or is this aspect different from radiant floors?
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Replies
This article shows one way of doing it:
https://www.pmengineer.com/articles/93157-looking-up-to-radiant-cooling
With the ceiling already in place you can do the same sandwich -- drywall, aluminum plates, 3/4" polyiso -- just build it in the opposite order. Since your attic is unconditioned there should be a minimum of R48 above the ceiling. I don't see the need for an air gap but the ceiling should be air sealed and the radiant loop should be on the conditioned side of the sealing.
Built this way I don't see any more risk of freezing than for water pipes inside the building envelope. I have a house in zone 5 and it is common to put propylene glycol in the hydronic water to guard against freezing in the case of power loss.
Ok. Yeah. I guess the poly detail in that drawing will be the air gap in question.
I guess the answer is if we insulate to R-100 that means we have 1/100th the heat loss. So if it would freeze after 1 hour, now it should take 100 hours. So you would hope that would make it so that it would turn back on before then.