Control does not seem to be doing anything.
No power is supplied.
Check circuit breaker, reset if necessary.
Measure the "Line side" voltage coming from the breaker panel at the control, test from "L1" to "L2".
  • Check all connections between breaker and control. Test the voltage at each connection starting at the breaker panel, proceeding toward the control.
  • A 120 Volt floor warming system has black and white power leads (with a ground wire).
  • A 240 Volt floor warming system has black and blue power leads (with a ground wire).
Wire connections at the control may not be correct.
Refer to wiring diagram on back of control. "Line side" wires connect to incoming power from the breaker panel and "load side" wires connect to the floor warming system power leads.
  • If the control still shows no evidence of having power supplied to it when it has been proven that it is receiving the proper voltage, try replacing the control.
Control shows an Error code on display.
Refer to the Error Code Chart in the instructions for your specific control for Error Code definitions.
The instructions for all of our present controls and many of our previous controls can be found on our web site, typically in the "Literature" section. The Error Code Chart is typically found on the last page of the operating instructions for the control.
The Error Code may indicate a loose connection with one of the components of the system, such as the floor temperature sensor.
Check the wire connections of the component that is indicated by the Error Code. Remove and re-install that component if necessary.
If you are getting an Er 2 code, the sensor wires may have too much exposed copper wire at the terminal connections to the control, which can allow bare sensor wires to touch.
Turn off the power to the control at the breaker panel. Remove the sensor wires from terminals 1 and 2 and test the resistance with a digital ohmmeter set on the 20k ohms scale as described in our installation manual.
  • If the sensor test shows it in range for the present floor temperature, trim the stripped ends to no more than 3/16" long and reinstall. Turn the breaker back on.
If you are getting an ER 6 code, it is an indication that the control became too warm internally. There are several possible reasons for triggering the ER 6 response.
The floor warming system may be drawing more than 15 amps of current, which causes the control to get too warm internally.
  • Test the amp load on the control. Each of our SunStat controls is rated for 15 amps maximum, whether 120V or 240V. Any load above 15 amps needs to be split up and use a "SunStat Relay", model # 500680 (order number 81009185), or another regular control to carry part of the system. Please note: Using another regular control will require another floor sensor for it to work with. A Relay does not use a floor sensor, it uses the signal from the main control.
Another heat source may be creating additional heat that is pushing the control past its internal temperature limit. Is there a lamp, a "space heater", a heat duct, or some other heat source close to the control? Can direct sunlight reach the control?
  • Try to remove any external heat sources from close proximity to the control.
The control may not have adequate ventilation to dissipate the heat it generates.
  • Our controls should not be installed inside cabinets. Cabinets are generally not well ventilated and that can cause too much heat to build up inside the control. The control should not be covered by heavy drapes or anything of a similar nature that prevent the control from dissipating heat.
Someone may have wired a 120 volt system to 240 volt power, which results in serious overheating within the floor warming cable as well as the control, and a much higher amp draw and wire temperature than the 120V floor warming cables are designed for.
  • Black and white power leads (with a ground wire) indicate a 120V cable.
  • Black and blue power leads (with a ground wire) indicate a 240V cable.
Turning the control off and back on with the switch on the control will not clear all Error Codes.
After making certain types of changes to the system or the control, it is often necessary to turn off the power to the control at the breaker panel, and then turn it back on to make the control go through a full "restart", in order to clear some of the error codes.
Control shows a GFCI trip.
Try turning off the control and turning it back on again, which should reset the GFI.
If the GFI trips again the next time the control tries to send power to the floor, the control may not be wired properly, refer to the wiring diagram on back of control.
  • "Line side" wires connect to the power supply coming from the breaker panel.
  • "Load side" wires connect to the floor warming system's power lead wires.
The floor warming cable may have a short to ground, which will cause a GFI trip.
  • Disconnect the system's power leads from the control. Use a digital multi-meter to test for a short to ground or short circuit as described in our installation manuals. If you detect a short circuit to the ground wire, contact the manufacturer before trying to locate the damage or make a repair.
If the GFI does not trip immediately when it starts delivering power to the floor, the system may have a "GFI conflict" with a component in the power supply circuit or a device that shares this power supply circuit with the floor warming system.
  • Some electric motors and various other electrical devices can cause nuisance GFI trips when nothing is wrong with the floor warming system. Try to determine if the GFI trip of the control happens at the same time something else in the home has just turned on. Whenever possible, we recommend using a dedicated circuit to provide power for our floor warming systems, which helps avoid most nuisance GFI trip problems.
The floor temperature sensor does not seem to be working properly.
The Floor Sensor may be damaged or may not be in the proper location with the sensor tip placed halfway between heating wires.
Installing a new sensor is typically easier than moving or repairing the existing sensor.
Try temporarily hooking a new sensor up to the control, the sensor can be left hanging in the air for this test. If it seems to give the control a better signal to work with, you'll have to determine which of the following two options might work better for your installation.
  • It may be easiest to install a new sensor in a grout seam. Avoid placing a sensor above a floor warming cable or too close to a floor warming cable, which often causes the system to "short cycle" and the floor may not warm up in a normal fashion. Call the manufacturer for more information on the best methods to determine a good location.
  • A new sensor can be installed from below the floor if you have access to that space. Call the manufacturer to discuss the best method for doing this.
Is there more than one sensor connected to the control?
Only one floor sensor can be wired to the control at a time. If you have an additional floor sensor, it is intended to be a back-up or replacement sensor in case the first one is damaged or not working properly. Verify there is only one sensor connected to the control.
The floor sensor may be damaged. It should be tested with your digital multi-meter.
A floor sensor can only be tested after disconnecting it from the control. If your digital multi-meter has more than one setting for ohms, it will need to be set to the 20k Ω scale (20,000 ohms), or your meter's nearest equivalent.
  • The sensor should measure about 7k ohms at 91 degrees F (33 C), or about 10k ohms at 77 degrees F (25 C), or up to approximately 20k ohms at 48 degrees F (9 C). It should be tested as described in our installation manual, and if you are getting a proper reading from it, please document the resistance value in the Resistance Log of the installation manual. If your sensor is not within calibration for the present floor temperature it will need to be replaced, contact the manufacturer to discuss your options for replacing a floor temperature sensor.

Please note: This is a Troubleshooting document. If you are not qualified to do electrical work, we recommend hiring a qualified, licensed electrician. Any troubleshooting work should be done with the power removed from the circuit unless otherwise indicated. If your problem can't be resolved with these tips, call SunTouch, 888-432-8932. These tips are provided to assist with troubleshooting our floor warming systems, results are never guaranteed. Watts Radiant does not assume any liability or responsibility for damage or injury that may occur from using these tips. Refer to the product's installation manual or appropriate instructions and warnings regarding installation, use and maintenance.