On Jun 26, 2009, at 10:36 AM, Ron Nossaman wrote: > Whatever it's called, the coils in the floor aren't radiant heat. > It's convection, like the old also mis named radiators. Cold air > sinks to the floor, is warmed by the floor, and little thermals > break loose as the air warms, and rise up as more cold air pours in > behind it from windows and walls. Radiant heat is just that. It's a > heating element that isn't intended to heat the air directly, but > warms everything in direct line of sight with it, which then warms > the air secondarily. They are often used in large buildings, like > hangars and auto shops, where there is a large air volume enclosed > and big doors open periodically. You can stand 50 feet away from a > radiant heater and feel it, even in below freezing air I'm not an expert on the physics of heat transfer, but I know a wee bit. The way I understand it, any material body that is "warm" emits infra-red rays - radiates heat. That's how those night vision goggles work: they pick up on those radiated infra-red rays. Yes, the way a radiant heated floor gets the air in the whole room warm is through a process of convection. But the air close to the floor "picks up heat" due to radiation (it is warmed by absorbing infra-red rays from the floor). It then travels up and is replaced by cooler air, which repeats the process. You could feel the radiant heat from a steam radiator, or from a radiant heated floor, from 50 feet away, if the source were hot enough. It's a difference of scale. Those industrial radiant heaters are awfully hot and put out a lot of energy in the form of infra-red. So is a hot wood stove. I believe the radiators or coils in the floor are usually limited in temperature to around boiling (old steam radiators) or well below (floors). Maybe there is a physicist out there who wants to set us straight on this. Regards, Fred Sturm University of New Mexico fssturm at unm.edu
This PTG archive page provided courtesy of Moy Piano Service, LLC