Greetings!
I’m planning to install a staple-up radiant system in my garage ceiling in order to heat the room above.
My home is quite old and drafty, and I’m considering having this area and a few others insulated with a spray-on expanding foam product.
Radiantec and others advise to leave an air gap between the insulation and the tubing/plates. I’m convinced that in my home this air gap will become a counterproductive cold draft tunnel.
As I see it, my options include:
– don’t use the spray foam insulation
– use the spray foam, but rig an air gap (possibly with a rigid foam board)
– ignore the recommendations and foam right over the tube and plates
Can anyone explain the air gap requirement?
What would you do?
Thanks!
Replies
Air gaps are *only* needed if you are not using plates. Hopefully you are using plates. If you have an old and drafty house, you may need heavy guage plates in fact, and if it's bad even those may not be enough... be careful, and make sure a true heat load calculation is done on a room-by-room basis.
If you are using plates, insulation can go right up to them. The air gap is entirely for suspended tube systems without plates, so you can make a small area for a convective loop to form around the tubes to increase heat transfer. It is a completely negligable factor in plate systems.
Go ahead and spray foam right over the whole thing, and pay particular attention to foaming the ends of the joists where infiltration may occur.
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Super, thanks for the information.The air gap makes sense in a non-plate context.I do intend to use plates and will bury the whole shebang in foam./chris