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Radiant Heat Not Working?

Moved into a house with Radiant heating running pipes in the floorboards. There are two zones: upstairs and downstairs. We had the heating loops looked at and completely redone (when we moved in, there was no pressure release tank, and a strange loop setup) because the heater would throw low pressure errors and shut itself off. That’s resolved with the new setup. 

The issue is the upstairs doesn’t seem to heat up. Downstairs I can feel hot spots when the heat is on, and in general, the temperature eventually rises to the set temp downstairs. Upstairs though, the heat can be set and pumping for two hours and nothing seems to happen. At the piping, the temperature going into that zone is hot (130 F) and returns fairly hot too (~110 F). Meanwhile, downstairs the return water is much cooler (~85 F). I just don’t see why the upstairs doesn’t get warm. The only think I can think of is that the pipes are not routed correctly somehow. Looking for suggestions or someone who knows the issue. 

Thank you.

Re: Radiant Heat Not Working?



There are two basic types of radiant in-floor heating systems: hot water and electrical. The hot water system produces heat by passing hot water through coils beneath the subflooring. The electrical systems produce heat by passing an electrical current through heating cables sandwiched between the subfloor and the finish floor. In some cases, the electrical heating cables are installed on the underside of the subfloor.


Wall Thermostats


A common cause of problems with any in-floor radiant heating system is a defective wall thermostat. Thermostats that do not open correctly will cause the room to become too hot. A thermostat that does not close properly will make the room cold all the time. Fortunately, thermostats are easy to check and easy to replace when defective.


No Heat


The wall thermostat controls line voltage to the zone valves in a hot water system and the current flowing through the embedded heating cables with an electric system. Begin your troubleshooting by making sure there is voltage present at the thermostat using a noncontact voltage tester. 


If there is no voltage present, you have a tripped circuit breaker or blown fuse in the service panel. Reset the breaker or replace the blown fuse and recheck for power. If there was power at the thermostat, check for voltage at the zone valve in the case of a water system, or the splice box in the case of an electrical system, using the noncontact voltage tester.


 No voltage at those points indicates a bad thermostat. To replace a thermostat or any other component in the heating system, first turn off the circuit breaker. Remover the cover from the thermostat, disconnect the wiring by loosening the terminal screws and slipping the wires out from under them. Remove the old thermostat from the wall and take it with you to get an exact replacement.



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