lawandorder said:
Thanks for the info. The reason I liked the Quick track was the fact it was only 1/2 and it would tie in nicely to the tile areas. I am putting carpeting back in place after its finished but I am a little concerned over the 5/16 being able to heat the room. I am using it in a large room with Cathedral Ceilings. Is there a general rule for BTU's with radiant in floor?? I want to make sure I have enough floor space to handle the heat load with a large room with windows and cathedral ceilings
The btu output of any radiant surface, regardless of the floor covering, has to do with the surface temperature.
Rule of thumb 2 btu/ square foot per degree difference. The difference between the surface temperature and the ambient air temperture.
So a room at 68F ambient and a radiant surface of 80 °F would output (80-68) X 2 about 24 btu/ square foot of surface. So the limiting factor becomes the surface temperature.
You have a skin temperature @ 80- 83 °F so the surface temperature should not exceed that or it becomes un-comfortable, sweaty feet , etc

Studies indicate 80- 82 °F as the high limit for radiant floors in homes. So in the end about 25 BTU/ square foot is a reasonable residential floor output.
More output would require either cooler room temperature, or warmer radiant surface temperature. This is where radiant walls and ceilings start to look good as you are not limited by that surface temperature. Unless you walk on your walls and ceilings.
Also commercial shops will see much higher outputs if they can design around cooler room temperature, and warmer surface temperatures with occupants in shoes. maybe 60 °F ambient, 85 surface = 50 BTU/ sq.ft. output.
What additional floor covering does is put a R value over your emitter Figure R1.0 for 3/4" hardwood and as high as R3- 4.0 for carpet and pad depending on the thickness and material Multiply X 1.5 for wool carpets.
So now you need a much higher water supply temperature to overcome the resistance of the floor covering.
You first need to know what the BTU/ sq. ft. load is of every room, the select the radiant design accordingly.
I'm not a fan of any carpet over radiant, and beware of max temperatures they can operate under before outgassing or breaking down of the foam pad.
For radiant surfaces bare concrete #1, tile over concrete #2, thin engineered hardwoods #3.
Certainly many floor coverings can be used with radiant, the devil is in the load and design. Crunch the numbers carefully before you start for a sucessful radiant installation. It's those design days and below that separates the "guestimates" from the designed installations. Nothing worse that an under-performing radiant system in the winter.
Supplemental heat is another option, let the radiant floor cover what it can, and kick on some radiant ceiling or radiant wall zones, or panel rads or fintube. Stay away from forced air supplement, it ruins the comfort of the radiant and stratifies the room, especially tall ceiling rooms.
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