I am in the process of building a house in Alabama and am seriously considering installing radiant heat flooring (open water design) as the main house heating method. I am concerned about two things. The first is whether radiant heating alone can adequately heat the house. The second concerns the interaction of radiant heating with a fireplace insert I plan to install. The insert is a high efficiency Quadra-Fire woodburning unit that, when used, should heat a portion of the house. My concern is whether this heat will fool the radiant heating in the floors to the extent that it will be difficult to maintain control over the system. In other words, will I have a hard time heating the areas of the house that are not heated by the woodburning unit becuse the radiant system has throttled back the temperature of the water in the heating coils?
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Andy
Never been to Alabama, but would think a radiant floor could easily do the job. You must realize that radiant (expecially in a slab) is not an on demand type of heat. You may find that the call for floor heat in the cold evening will overpower you in the warming of the temp outside.
The right controls are needed to avert this as well as zones to divide up the areas according to need.
NRTrob who posts here is a much better source of information.
Design and layout are keys to radiant comfort.
First, definitely do not do an "open water" design. Please. Especially not in Alabama where the heating season is not very severe.
Second.. how are you thinking you'll install the radiant, in a slab on grade? If so, in your area and with a woodburning stove, there are definitely control issues to consider, namely, thermal lag and lead time. These are addressable but would require a significantly more sophisticated control strategy than "thermostat on, thermostat off".
Your specific concern, however, is addressed by "zoning" the areas without the woodstove influence on their own thermostat. Very important!
Third, your capacity question is answered by a real room by room Manual J heat load calculation... This will also tell you if you're ever likely to experience warm feet in your climate, as floor temp is a function of heat load and you're not in a severe climate.
and Pro Tip: if it's not Manual J or equivalent, it's *probably* bunk. There is some real garbage being generated by some very popular sites out there that pretends it's a heat load calculation but really is just smoke and mirrors. an "Energy Factor" in the calculation is a dead giveaway that real calcs are not being done.
RE:
Thanks for the comments. NRTRob, are you saying that because of the mild winters in Alabama, the heat system may not work sufficiently on certain days and we would not ever get to experience "warm feet"? I did figure that I would need a more sophisticated control system on days when the house is being heated by the woodburning fireplace.