Radiant ceiling heat is a style of heating that is significantly different from the radiators or forced air ducts that you may be used to. Radiant ceiling heat comes in two main forms. In the older form, electric heating elements are sandwiched between a layer of drywall and a layer of plaster. This style of radiant ceiling heat is much harder to fix when it fails. The newer form involves radiant ceiling heat panels.
The heating elements are contained in modular tiles the installer fastens to the roof with screws. In either form the panels are wired to a 120 volt or 240 volt alternating current power supply. If you believe your radiant ceiling isn't producing heat, there are several ways to test. It is much easier to confirm the source of the problem if you have an infrared camera and a multimeter. If you aren't fortunate to have an infrared scanner, you can always push your hand against the ceiling panel in question to see if it is heating up. If the ceiling is cold, there are several possible causes.
Step 1 - Check Circuit Breaker
The first step is to make sure the breaker for the electrical resistance heating element hasn't tripped. If this is the problem, just reset the breaker and the heat should work. If the breaker continues to trip the circuit it may be shorted or overloaded. Have a professional electrician examine the installation before it becomes a fire hazard.
Step 2 - Check Wiring Connections
If the circuit breaker hasn't tripped, check all the visible wiring you possibly can. A break in the wiring renders the circuit incomplete. The heating elements won't work because they aren't receiving electricity. Look out for corrosion or loose connections.
Step 3 - Check Heating Elements
In some cases, the heating elements themselves may have broken. There are several ways this can happen. It may be due to a manufacturing defect or the installers' error. In the older types of radiant ceiling, air bubbles in the plaster can cause the heating element to burn out. In older construction, a drywall ceiling may eventually crack and sag due to moisture or excessive load. This can mess up the radiant heating elements inside the ceiling. It is also possible to damage radiant ceiling heat panels by carelessly driving screws through the floor of the attic above. You can check for continuity inside the concealed parts of the radiant ceiling using a multimeter.
Step 4 - Check Thermostat
If the radiant heating elements and electrical circuits check out, but you are still not happy with the system's performance, your problem may lie with the thermostat. Be aware that radiant heat systems are controlled slightly differently than forced air systems. There is approximately a ten degree temperature range. The system will activate about five degrees below the thermostat setting, and shut off five degrees above it. Large temperature windows or highly variable operation suggests poor thermostat setting. On the other hand, if the system doesn't cycle on or off, this indicates a miscalibrated anticipator or broken thermostat.