staple up w plates insulation opitions

clammy

Wonder what the train of thought is on insulating a extruded plate system.I am kinda on the fence weather to insulate with a air gap or with out .I am leaning towards leaving no air space and insualting w a mimiun of r 30, the  basement is heated .My feeling is that with out a air space and using  plates i will get a better responce and better out put at lower temps then with a air gap,Thanks peace and good luck clammy

Gordan

All things equal, I can't see the gap hurting

In my mind's eye, all it does is provide more paths (albeit not necessarily good ones) for the heat to get from the tube to the floor. The thermal mass of the air in the cavity doesn't amount to much, so I wouldn't expect it to substantially impact response. Heck, I'd spray paint the bottom of the plates to increase emissivity!



What could go wrong? With insulation being the same in both cases, increased downward heat loss is only possible if the average temperature of the cavity increases, and that can only be good for output (and evenness of output.) Or, it could take too long for the floor to come up to temperature, but that seems unlikely for the reason I already addressed.

Zman

Air space

I have done quite a few with an air space and never had a problem. I have heard people say it is not needed. I have not had the nerve to try it without. I just don't see the upside.

Carl

NRT_Rob

if you have plates

you don't need an airspace. difference is minimal in the extreme.

Dave H_2

Air Gap and plates

There have been several types of radiant plates over the years.

One style wants an air gap, one doesn't.

The thin stamped style plates want an air gap to help with convective heat transfer and minimize temperature striping on the floor.

The heavier extruded plates wants to transfer heat by conduction. An air gap with insulation will slow down its transfer of energy. The heavier plates typically also require a lower water temperature to do the same thing.



Dave H.

NRT_Rob

to clarify

only one type of plate wants convection, it's called "ultra fin". there are light plates that are conductive that are the vast majority of light plate joist installs. no airspace needed there.

RobG

Air Gap

My argument against an air gap with plates is that with an air gap you are filling that 2" area with hot air. That hot air is going to want to exit to a cooler area by the easiest means available, wire and pipe penetrations, soffits, edges, band boards etc.. Where as eliminating the air gap, the conduction is going to go through the easiest place, UP (if radiant floor), eliminating the convective heat-loss. If you leave an air gap, you are creating a duct in every joist bay, and with ducts, there are duct losses.

Just my 2 cents.

Rob