We don’t see a lot of raraint floor heat in KY. What is the temperature of a radiant slab?
The reason I ask is that I recently had a VCT vendor tell me that Armstrong would not warrenty thier commercial grade VCT over a slab that stays at 104 degrees F. Something doesn’t sound right about that explanation. Is this an issue with floor covering over all radiant floors, or am I get smoke blown up my pipes?
dave
Replies
Dave,
You'll find reams of stuff on the subject in the archives.
IMO, I shoot for having the slab reach 99 degrees tops. Average: 96 degrees.
Having the slab hotter sounds to me as if there is a problem with the building's envelope. A radiant system is dependent on a well insulated structure. Again, my opinion............
When I was looking to use an in-slab thermostat sensor instead of an ambient temp tstat, the general guideline I was given was to set the tstat measuring slab temp for 10 degrees over your desired room temp. So 104 _floor_ temps shouldn't be necessary under that guideline. Of course, the water temp could easily be higher...
I should clarify this a little.
I was courious about radiant slab temperatures because of the flooring issue. What I have is not a true radiant floor, although the floor temperature is 104 degrees.
The floor is in the administration office of one of our power plants. The floor below the area is occupied by the inverter equipment, two domestic water boilers, and other generating equipment that I don't have clue about. Everything down there generates heat, and to make matters even worse, the admin. office sits between unit number two and three boilers. There is no way to insulate the floor from below because of the vast amount of wire tray, ducts, and piping. The floor temp. and many other things (like coal dust) are just a fact of life in a power plant.
If radiant floor slabs only reach 99 to 100 degrees, then I can understand the vendor being unwilling to bid vinyl composition tile over a slab that is 4 to 5 degrees warmer than a normal radiant floor. The current floor is a straight vinyl product, and it failed in four years. The installed cost was $32K, and I am reccomending that nearly the same amount be spent to replace it with ceramic.
Thanks for the information.
Dave
Did you in fact use an in-slab thermostat sensor? Would you recommend it over an ambient temp thermostat? Thanks..........
No, I didn't. I wanted one with a digital readout that also had a typical thermostat look, and the only thing available was something called a set-point conroller. We have them on our hot and cold water storage tanks, but they aren't quite the look I wanted for the living room. Someone's trying to come out with one, but it's not UL listed yet--available only in Europe at the time. So I spent one winter messing with different tstat settings, and finally found the right setting that allows it to run automatically without being too affected by solar gain.