Hello Folks,
I had my plumber install radiant heat in my master bathroom. Pex tubing is under 3/4 floor deck, 1/2″ subfloor and then thinset and marble tile. It’ never worked – floor is cold except in one small spot. He’s a pretty good guy but now he’s telling me it may never work because of the wood (5/4 with the two floors.) I’ve had the thermostat turned up to 90 for the last month after the last purge but SOL…so anyway, can anyone please chime in how we can go about figuring out why its not working or is it a matter of the insulating factor of the wood (which doesn’t make sense to me as the floor is cold – you would feel something I think and the problem would be maintaining the tempature – we don’t have anything). Thermostat in the line tells us that the liquid in the pex is heated.
Anyway thanks in advance for the help.
Devin
Replies
Pump works, no zone valve?
If a grundfos (or other, probably) pump, both isolation valves open?
Where is this thermometer on the line?
What's the boiler (or other) temperature?
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Edited 1/11/2007 10:26 pm ET by calvin
Is the PEX in the joist spacing? If so did the installer use heat transfer plates? Check the flow rate. What type of heater are you using?
Pretty much start from the top.
You're getting some hot water but how much, and at what temp? Is the tubing warm/hot when you touch it? Is the t-stat actually kicking the heater and circulating pump on? Are all flow valves that need to be open, opened?
Could be insufficient flow. Undersized pump, valves not opened all the way, flow restrictions through the manifold, kinks in the tubing, air bubbles in the tubing.
Is the circulated water sufficiently hot? Mixing valve opened, etc, etc.
How much insulation do you have under the tubing? Is it tight to the tubing (good) or are you heating the entire volume of the joist bay (bad).
If you have one, have you gone through the setup on your control box?
In my house I have 3/4" ply subfloor, then 1/2" ply underlayment, then hardwood flooring on top of that. Staple-up PEX under the subfloor, no plates. 1/2" foil-faced polyiso under the tubing, friction fit between the joists. Fiberglass underneath that. I circulate 110-120 degree water. Working like a champ for the past 10 years.
Mongo
Mongo,
My test place worked just fine, it's two inch thick (actual not demensional)subflooring with actual one inch thick flooring on top of it! Total of three inches.. .. I nailed a plate made from aluminum flashing material to the bottom side right over the pex (I ran the aluminum flashing over a bead roller that put a dimple in the metal. Roofing nails hold the flashin up in place.
The bay is stuffed with fiberglas insulation and a sheet of foil faced foam insulation holds everything up.. Took more than 48 hours for me to really feel the warm floors but they stay nice and warm for a long time after I shut the system down.. I used a water heater because of their efficency.. So no cold water mixer was needed. should have bought a differant thermostat to control the on off switching of the water heater, I just kept it on steady and lowered the water temp to what I liked..
Crude but it worked and that's all I was testing..
In a new installation you may have an air pocket in the loop. I had a real stubborn one the fix was to use a sepparate pump and pump water througt the loop in both directions.
Thank you very much guys. I will work to get answers to all the guestions and see if we can come up with a game plan - will let you know how we make out.
Thanks again,
Devin