Radiant Heat and wall thermostats

Big Ed_3

Is to use floor sensors rather then thermostats to maintain a 85*ideal floor temperature .

Phil_24

Radiant heat and wall mounted thermostats

Efficiency question.......
I have a radiant heat system (propane & boiler) that has zones that run off of wall mounted thermostats. In the winter I set the zones that I use at about 66 degrees. I also have a heat-o-lator type fireplace that I use (wood burning). When I use the fireplace, it heats the zones I use most to about 71 degrees on the wall thermostats. This would turn the radiant heat flow off. Then, when we go to bed the temperature drops and the radiant heat in these zones would turn back on(set at 66 degrees). Does this situation cause the use of more propane, due to the system having to heat the concrete core up again, than not using the wood heat and leaving the radiant heat only on a steady 66 degree thermostat setting??

Glenn Sossin_2

Typo ? You really didn't mean 85F

If he maintains an 85F floor temp, he'll be sweating most of the winter - (that is unless he leaves the windows open). Assuming an indoor design temp of 68F, with a surface temp of 85F, he would be generating approx 34 btu's per sqft. Thats a whole lot of heat energy.

I agree you could use a floor sensor, but not to maintain 85F. You might use it to maintain a minimum floor temperature that won't heat the room when its a mild temp outside approx 55F -60F. It would probably be set so it yields an avg floor temp of around 68F-70F. This way the floor temp won't drop too low, but you also won't heat the room on a mild day unless the thermostat actually calls.

The situation you describe is common in a kitchen where the is a lot of extraneous heat energy being generated from appliances and cooking. The room temp can be much higher than the thermostat set point such that the heat doesn't come on for an extended period. This may allow the floor to cool down too far and increase the response time of the next heating cycle.

As far as heat consumption, it won't increase your energy usage but will increase your response time on the cycle when it first turns on again after the wood burning stove burns down.