Radiant Heat with Carpet

Tom Hopkins

I believe the RPA has done some research and notes the "R" value of a plethora of carpet/underlayment conditions.

However, common sense is a great general design parameter. The greater the "R" value of the material the energy must pass thru (sub-flooring, flooring, pad, carpet, throw rugs, etc.) the higher the water temperature must be in the tubing to make it to the surface of the top layer.

In all cases, the lower the water temp can be, the better. At some point, the cost to make the water 180 or above - to meet the BTU output of the radiant system needed - will exeed design physical limits, never mind destroy any benefits a decent mod-con can achieve, by virtue of them requiring under 160F water temps to achieve the highest level of efficiency.

If efficiency is NOT a consideration, running water at 240F could probably make surface temps around 85-90 (the practical design limit of surface temps desired in a radiantly heated room,) even with a 3/4" sub-floor, 3/4" hardwood top, 5/8" underlayment, and 1" tall carpet!

Unfortunately, it would take a day of 240F water passing thru to penetrate the "thickness" and R-value of such a floor.

If a 4" concrete slam with tubing in situ is trhe best of the best radiant method, the worst case scenario above would be the worst of the worst scenarios.

Does that help?

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Granite Stater

Radiant Heat with Carpet?

I am building new house and I would like to know if I can use carpet in the upstairs? If so, should I use a rubber pad instead of the foam pad? The down stairs will be tile & Kahrs wood flooring. All the bathrooms will be tile.

Granite Stater

Ed_26

carpet upstairs

Why not a radiant ceiling?

kal_2

The “carpet everything” mindset was borne…

From cold floors – but carpets are unhealthy period!!! From carpet mites, pet flees, mold, to out-gassing of the chemicals in them – especially when heated

In a radiant house – carpets are limited to pad sized ones, in baths, by entry doors, between beds, and “runners” in upper hallways for quietness – thats it!!!

If you absolutely must do carpet – then, save your money , do panel or cast iron radiators , you can pipe them off a radiant manifold with pex home runs as well


And you can run them on the same water temp as the rest of the house’s radiant – for cast iron it will typlically have to be ½ larger in surface area though - yes - a cast iron radiator that visible to all in the room works well at 120F and even below

hot_rod

Two thumbs down to radiant and carpet

from this installer.

First off look at the btu load for those rooms. Then determine the supply temperatures needed to meet that load on design day.

I'd caution against any temperature above 130 against plywood or the other subfloor products. I believe 140F is the max that plywood manufactures like to see for extended periods.

I would also look into panel rads, baseboard, ceiling and or wall radiant, before scorched carpet All these would be much more responsive and allow setback operation.

What about hardwood and area rugs?

hot rod

Glenn Sossin_2

been doing it for years

I have it in my home in 3 different bedrooms, 3 different types of carpet with climate panel, running straight out of my boiler controlled by indoor outdoor reset.

Been designing for it also but let the computer software be my guiding force. Sometimes, we can't get enough heat out and have to use supplemental heat i.e. walls.

I had to do that in my family room.

So far, 4 seasons later, everything seems to be ok.