SunTouch SunStat Thermostat Troubleshooting

Table of Contents

1. The thermostat does not seem to be doing anything
2. Control shows an error code on the display
3. Control shows a GFCI trip
4. Floor temperature sensor isn’t working properly
5. You need to replace your thermostat but aren’t sure what model to get

The thermostat does not seem to be doing anything

1. Check to make sure that there is power supplied to the thermostat.
2. Check the circuit breaker and try resetting the breaker.
3. Measure the “Line side” voltage coming from the breaker panel at the control and test from “L1” to “L2.”
   • Check all connections between the breaker and the control. Test the voltage at each connection starting at the breaker panel and 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).
4. The wire connections may be incorrect. Refer to the wiring diagram on the back of the 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 the display

Check the wire connections of the component that is indicated by the error code. Remove and reinstall that component if necessary.

Error 2:

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. This can allow bare sensor wires to touch.

1. 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 Ω scale (20,000 ohms) as described in the 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.

Error 6:

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.

1. 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 SunTouch SunStat control 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 or an additional thermostat to carry part of the system.
   • Please note: Using an additional thermostat will require another floor sensor for it to work with.
2. Another heat source may be creating additional heat that is pushing the control past its internal temperature limit. Is there a lamp, space heater, heat duct, or some other heat source close to the control? Can direct sunlight reach the control?
   • Try to remove any external heat sources in close proximity to the control.
3. The control may not have adequate ventilation to dissipate the heat it generates.
   • SunTouch controls should not be installed inside cabinets. Cabinets are generally not well ventilated, which 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 prevents the control from dissipating heat.
4. If a 120-volt system was wired to 240-volt power, serious overheating within the floor warming cable as well as the control will occur, causing 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.
5. Turning the control off and back on with the switch on the control will not clear all error codes.

Note: After making certain types of changes to the system or the control, you may need 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.

Error 7:

The error 7 code means that the thermostat has reached the end of its life and needs to be replaced.

The warranty on the thermostat is 3 years. If it has been less than 3 years since the date of purchase, contact the distributor you purchased from and they can get you a replacement.

If you bought from us just call us at 1-866-558-3369 with your original order number and we can get you a replacement. If it has been more than 3 years from the date of purchase you’ll need to buy a new one.

If the error code is not listed above, please refer to the proper installation manual.

Control shows a GFCI trip

1. Try turning off the control and turning it back on again to reset the GFCI.
2. If the GFCI trips again, the control may not be wired properly. Please refer to the wiring diagram on the 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.
3. The floor warming cable may have a short to ground, which will cause a GFCI trip.
   • Disconnect the system’s power leads from the control. Use a digital multimeter to test for a short to ground or short circuit. If you detect a short circuit to the ground wire, contact the manufacturer before trying to locate the damage or make a repair.
4. If the GFCI does not trip immediately when it starts delivering power to the floor, the system may have a “GFCI 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 other electrical devices can cause nuisance GFCI trips when nothing is wrong with the floor warming system. Try to determine if the GFCI 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 a floor warming system to avoid most GFCI 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.

1. Try temporarily hooking up a new sensor 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 to not warm up in a normal fashion.
   • A new sensor can be installed from below the floor if you have access to that space.
2. Verify that there is only one sensor connected to the control. Only one floor sensor can be wired to the control at a time.
3. The floor sensor may be damaged. Test it with your digital multimeter.
4. A floor sensor can only be tested after disconnecting it from the control. If your digital multimeter 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°F (33 C), or about 10k ohms at 77°F (25°C), or up to approximately 20k ohms at 48°F (9°C). If your sensor is not within calibration for the present floor temperature, it will need to be replaced.

If the issue is not listed above, please refer to the proper installation manual.

You need to replace your thermostat but aren’t sure what model to get

If your thermostat has stopped working or you’re ready for a thermostat upgrade, you can replace your SunStat with any available SunStat model. All SunTouch systems are compatible with any SunStat thermostat and replacement is simple.

Browse compatible SunTouch SunStat models or call 1-866-558-3369 for further assistance from one of our experts.