In my current house I installed radiant heated floors. 2 runs of 1/2" pex suspended between each 16" deep TJI on 16" centers (this is not a good method, as I found out later for low temp. Modcon boilers) but it works because of my high insulation levels & triple pane with an outer 4th layer of glass storm windows + 80g buffer tank.
Based on boiler firing rates at design temp. Of 0*F somewhere around 8-10 btus / ft2 / hr.
ICF basement & 8" SIP upper 2 levels.
Radiation & convection moves the heat from the pex into each plenum.
The pex is hung to the subfloor with plastic electrical clamps, but makes zero contact.
About 10" below the pex is a layer of Reflectix. It keeps somewhere around 80% of the heat above it to conduct through 1.25" OSB subfloor + 1/2" cement board + 1/2" of tile & thin set & radiates into rooms above.
After 14 years. I see no degradation over this time. The bottom surface of the Refectix has very low emissivity, so IR don't radiate much downward.
Last edited by buffalobillpatrick; 09-25-14 at 05:05 PM..
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