![]() ![]() In a tight house, it's true that the low heat demand would require a lower floor surface temperature, and that might mitigate against the "warm toes" effect. sf, which would not be nearly enough for most poorly-insulated (let alone drafty) homes.This is because these systems take a long time to warm up and cool down and are thus typically operated to maintain near-constant temperature day and night.Īlex, you suggest radiant floor heating for a high heat-load, drafty house, but a floor at a maximum 85° surface temperature can deliver only 34 btu/hr The set-back thermostats I described in last week’s column aren’t effective. One last point: if you do install a radiant-floor heating system, be aware that it should be controlled differently than other central heating systems. Some people use light-weight gypsum-concrete slabs that are poured over existing floors others attach the radiant tubing underneath a wood floor or subfloor. I like to benefit from the thermal mass of a slab floor with embedded radiant tubing, and that’s a difficult retrofit project. ![]() If you’re thinking about radiant-floor heat for your current house, the challenge is that these systems are not easy to install in existing houses. In a house with a relatively large heating load, and especially in a drafty house, a radiant-floor heating system is a great option. In existing houses or in new construction when fairly standard energy details are being used, radiant-floor heating makes lots of sense. In a more typical superinsulated house, we can provide the desired comfort with one or two through-the-wall-vented gas space heaters or a few lengths of inexpensive electric baseboard heating element.Īgain, these arguments apply to highly insulated houses - usually new construction - when you can pull out all the stops and far exceed typical insulation standards for New England. Homes built to the rigorous German Passivhaus standard (which I’ll describe in a future column) can be heated with, literally, a few incandescent light bulbs in each room. I’d rather see someone spend that $10,000 on better windows, more insulation, and so forth - then recoup some of that extra cost by spending less on the heating system. Radiant-floor heating systems, with tubing embedded in a concrete slab, multiple pumps for different zones, and sophisticated controls, will easily cost $10,000. My second issue with radiant-floor heating has to do with economics. In short, radiant-floor heating just isn’t a good fit with superinsulated houses. And, if you’re delivering heat to the floor during the nighttime, and then have significant passive solar gain during the daytime, overheating is likely to occur. So you may not get that delightful benefit of a warm floor surface. If a concrete-slab or tile floor surface is maintained at 72 or 75 degrees, it will likely feel cool underfoot-since it’s at a lower temperature than your feet. First, in a highly insulated house (and I’m talking about a really tight house with at least R-40 walls, an R-50 ceiling, and triple-glazed low-e windows), such a tiny amount of supplemental heat is needed that a radiant floor needs to be kept no more than a few degrees above the air temperature-or else overheating will occur. I have two concerns, both of which apply only to very energy-efficient - superinsulated - houses. So, what’s wrong with radiant-floor heating? And because there aren’t baseboard radiators, furniture can fit right up against the wall. ![]() ![]() Radiant heat also tends to have less of a drying effect than does forced-air heat. If we’re used to drafty old houses, there’s nothing nicer than a floor that’s warm underfoot and gently radiates heat upward. Most people with radiant-floor heating absolutely love the warmth underfoot you can walk around barefoot even in the middle of winter. You might be able to keep your thermostat lower - say 65 degrees-and be perfectly comfortable with radiant-floor heating, while 68 or even 70 degrees would be required with other systems. This means that radiant heat can provide comfort at a lower air temperature than is required with forced-warm-air or baseboard hot water heat. It’s uniform, and it warms people directly, rather than having to heat the air. The heat is distributed over a large surface area, so it is delivered at a relatively low temperature. Radiant-Floor Heating: When It Does-and Doesn’t-Make Senseīefore explaining why radiant-floor heating is a poor choice in new construction, let me describe what I like about it. Should I Turn Down Radiant-Floor Heat at Night? Is Radiant Floor Heat Really the Best Option? ![]()
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