Your Ohmmeter may be set on the wrong scale, for instance, the 200k ohm scale measures up to 200,000 ohms, or 200k Ω.

Set your meter to the appropriate scale for the panel you have. For example, set on 200 Ω for an UnderFloor panel with a resistance range below 200 ohms. Then retest.

Some of our UnderFloor panels have a resistance range above 200 ohms.

  • Set your ohmmeter on a scale that goes high enough to test the panel you have, often the 2000 ohms scale, or 2k Ω. If your panel's reading is outside the range on the nameplate label, call the manufacturer.

If the ohm reading is a little high or low, test the meter itself.

Verify your meter is still working and properly calibrated by setting it on the 200 Ω scale or the lowest scale on your meter and hold the test probe tips directly together to test the meter's "zero reading", often reading about 0.1 to 0.4 ohms. A reading of "OL" (open line, or over limit) is not the same as a reading of 0.1 ohms.

  • If your meter does not pass the calibration test with a zero reading of significantly less than 1 ohm, one of the test leads might be damaged, or the meter itself may be damaged and needs to be replaced. If this is an older meter, it may just need new batteries.
  • If you can't get your meter to pass this calibration test, you need a multi-meter with a smaller margin of error before proceeding.
  • If your ohm reading for the heating circuit was just a little high, the "zero reading" from your ohmmeter can be subtracted from your heating panel ohm value. If the panel still isn't within its ohm range, call the manufacturer. 

Resistance readings for UnderFloor panels must be taken from only one panel at a time.

Verify you are testing only one UnderFloor panel, and test it directly from the factory power leads. If it is not within the Resistance Range for your panel, call the manufacturer.

Your ohmmeter may not be set up properly, or it may have a problem with one of the test leads, or it may simply need new batteries.

The ohmmeter must be set on the proper scale to test the heating circuit, typically the 200Ω scale for an UnderFloor panel with a resistance range below 200 ohms. Follow the directions for testing the panel as described in the installation manual.

Some of our UnderFloor panels have a resistance range above 200 ohms.

  • Set your ohmmeter on a scale that goes high enough to test the panel you have, often the 2000 ohms scale, or 2k Ω. If your panel's reading is outside the range on the nameplate label, call the manufacturer.

Test the ohmmeter itself. Verify your meter is still working and properly calibrated by putting the two leads directly together to test the meter's "zero reading", often reading about 0.1 to 0.4 ohms. A reading of "OL" (open line, or over limit) is not the same as a reading of 0.1 ohms. 

  • If your meter does not pass this calibration test with a reading of significantly less than 1 ohm, one of the test leads made be damaged or the meter itself may damaged and would need to be replaced. If this is an older meter, it may just need new batteries.
  • If you can't get your meter to pass the zero reading test, you should try to find a multi-meter with a smaller margin of error. 

If your multi-meter is in working condition but you still get no ohm reading from the UnderFloor panel, the heating cable may have been damaged. We have rental tools to help locate the damage.

We have splice kits to repair the cable after the location of the damage has been determined. 

If the location of the damage is known, you need a Heating Cable Repair Kit and the proper tools to complete the repair.

If the location of the damage is not known, we have rental tools that can help you find the damage.

Is the proper voltage supplied to the control?

Test the "line side" voltage at the control. Does it match the voltage specified for the UnderFloor panel on its nameplate tag?

  • Black and white power leads (with a ground wire) indicate a 120V panel.
  • Black and blue power leads (with a ground wire) indicate a 240V panel.

Test the "load side" voltage of the control while the control indicates it is heating the floor. Does it match the voltage specified for the UnderFloor panel on its nameplate tag?

Black and white power leads (with a ground wire) indicate a 120V panel.

Black and blue power leads (with a ground wire) indicate a 240V panel.

If control indicates a GFI trip, it will not send power to the floor. Reset the GFI by turning it off, then turn it back on. If it trips the GFI again...

The control may be mis-wired. Check the wiring diagram on back of control.

The UnderFloor panel may be damaged. Test the panel for proper resistance and check for a short to ground with a digital ohmmeter as described in the installation manual.

  • Multi-meter shows a short to ground. Contact the manufacturer. We have rental tools to help locate the place where the short has occurred, and splice kits to make the repair.
  • Multi-meter shows the heating circuit is not within the Resistance Range for this panel. Write down your resistance reading and contact the manufacturer.
  • Multi-meter does not detect a short to ground. This panel may have a very high resistance short to ground that a standard multi-meter can't detect. A Mega ohmmeter or a Hipot Tester can determine if your panel has a problem with the insulation on the heating circuit. Contact the manufacturer for more information about proper use of these tools and other methods of testing of the UnderFloor system.

A loose connection can cause a GFI trip. Check all wire connections between the breaker in the breaker panel and the floor warming system.

Sometimes another device in the home may be causing nuisance GFI trips when nothing else is wrong with the UnderFloor system.

  • Some devices unrelated to the floor warming system can cause nuisance GFI trips of your control, often instantly when the other device is turned on. If your control will operate for a little while before the GFI trip occurs, the actual source of the problem may be an electric motor or a ballasted lighting system in the house. This is a fairly common problem when using a shared circuit for the floor warming system. We recommend a dedicated circuit to provide power for our systems whenever possible.

Control is flashing "Floor Limit" in the lower left hand area of display, but the floor is not getting as warm as desired.

Our digital controls have the ability to limit the maximum floor temperature for laminates, engineered hardwoods, and similar floor covering materials to avoid overheating and damaging the floor covering. The factory default floor limit setting is 99°F for most tile and stone floors, but should be set lower for some floor coverings. If the Floor Limit temperature is reached, the control will flash "Floor limit" in the lower left corner of the display and the floor will not get any warmer.

  • Check your control's floor limit temperature by pressing the "Options" button as described in the control's instructions sheet until the Floor Limit temperature shows in the display. Use the up (or down) arrow to adjust the Floor Limit temperature to the desired floor temperature limit.
  • If two floor temperature sensors are wired together in parallel to the control, it will give the control an artificially high floor temperature indication. In this case the control typically shows a very high floor temperature, or it may not be able to convert the signal into a normal floor temperature reading at all. Verify you only have one floor temperature sensor attached to the control.
  • The floor temperature sensor may have been damaged, it needs to be tested. Disconnect the floor sensor and test it with a digital multi-meter set on the 20k ohms scale as described in our installation manual. If it is not within range for the approximate floor temperature at that time, it will need to be replaced. Call the manufacturer to discuss the options for achieving this.
  • You may be able to use the Air Sense mode or Regulator mode to warm the floor, but these may not meet your expectations for long term operation of the system. Call the manufacturer if you want to discuss these options.

Insulation may not have been properly installed, or may not have adequate "r value".

Check the insulation below the UnderFloor system, particularly at the ends of the heated joist bays and verify there are no gaps in the insulation where warm air could escape.

Check the "R value" of the insulation below the panels, it should be R-13 to R-19 fiberglass.

We do not recommend using spray type foam insulation under this type of system. When it "expands" it can flow on top of the UnderFloor panels and prevent some of the heat from reaching the floor above.

  • Fiberglass insulation is recommended, R-13 to R-19. Please refer to the installation manual for details on how it should be installed.

UnderFloor systems typically take an hour or more to warm up depending on how the floor was constructed.

Give the system another hour of constant heating time, if it does not seem to be warming the floor, call the manufacturer.

The control may have been "bypassed".

If the control has been bypassed, the floor may stay warm when the power switch of the control is in the Off or Stand by position.

  • Check the wiring diagram on the back of the control. Verify each of the wire connections is correct and you have four wire nut connections to the control (and a fifth wire nut connection for the ground wires).

Your control has the proper wire connections per diagram on back, but your multi-meter shows full line voltage on the "load side" of the control when you believe it should not be sending power to the floor.

If it is a programmable control, there may be an error in programming. 

  • Refer to the instructions for your control and verify all of your cycle times are programmed correctly and all cycle times for each day fall between 12:05AM and 11:55PM, in a logical progression through the day.

There may be a problem with the floor temperature sensor itself, or it may not be in the proper location.

  • The floor temperature sensor may not be connected to the control properly. Refer to the installation instructions for your control and inspect the present floor sensor connections. With our "SunStat" controls, a single floor sensor's wires should be found only in terminals number 1 and 2, and make sure they are firmly held in place.
  • Disconnect the floor temperature sensor and test it with a digital multi-meter able to test up to 20,000 ohms (20k Ω) as described in our installation manual. Is it in proper resistance range for the present floor temperature? If it is not, call the manufacturer.
  • If the floor temperature sensor seems to be in the proper resistance range but the control does not seem to track the floor temperature properly, the floor sensor may not be installed in the proper location. Installing a new floor temperature sensor is often easier than moving the one in the floor. Refer to the installation manual, or call the manufacturer for options on how you can do this without removing tile.

The contactors in the control may be locked in the "On" position. 

  • Verify each of the wire connections is correct per the diagram on the back, and you have 4 wire nut connections to the control (and a 5th wire nut connection for the ground wires). If your multi-meter detects line voltage on the load side wires of the control when it is turned off or in "Stand by", the control will have to be replaced.

Your Ohmmeter may be on the wrong scale. For instance, the 200k ohms scale measures up to 200,000 ohms, or 200k Ω.

The meter should typically be set on the 200 ohms scale (200 Ω) for testing cables with an ohm value less than 200 ohms. If your mat is outside the range on the nameplate label, call the manufacturer.

Some of our products have a resistance range above 200 ohms.

  • Set your ohmmeter on a scale that goes high enough to test the product you have. Many meters have a 2000 ohms scale, or 2k Ω. If your mat is outside the range on the nameplate label, call the manufacturer.

If the reading is a little high or low, test the meter itself.

Verify your meter is still working and properly calibrated by holding the test leads directly together to test the meter's "zero reading". Often, reading about 0.1 to 0.4 ohms. A reading of "OL" (open line, or over limit) is not the same as a reading of 0.1 ohms.

  • If your meter does not pass the calibration test with a zero reading of significantly less than 1 ohm, one of the test leads might be damaged, or the meter itself might be damaged and need replacement. If this is an older meter, it may need new batteries. If you can't get your meter to pass this calibration test, try to find a multi-meter with a smaller margin of error before proceeding.
  • If your ohm reading for the heating circuit was just a little high, the "zero reading" from your ohmmeter can be subtracted from your heating circuit ohm value. If the mat still is not within its ohm range, call the manufacturer.

Resistance readings for our mats must be taken from just one mat at a time. Is it possible more than one mat may have been wired together in series or in parallel?

Verify you are testing only one floor warming mat, and test it directly from its factory installed power leads.

Your ohmmeter may not be set up properly, or it may have a problem with one of the test leads, or it may simply need new batteries.

The ohmmeter must be set on the proper scale to test the heating circuit, typically the 200 Ω scale for a mat with a resistance range below 200 ohms.

Test the ohmmeter itself. Verify your meter is still working and properly calibrated by putting the two leads directly together to test the meter's "zero reading", often reading about 0.1 to 0.4 ohms. A reading of "OL" (“open line” or “over limit”) is not the same as a reading of 0.1 ohms.

  • If your meter's calibration does not pass this zero reading test, one of the test leads made be damaged or the meter itself may damaged and would need to be replaced. If you are using an older meter, it may just need new batteries.
  • If the zero reading from your meter is not significantly less than 1 ohm, try to obtain a multi-meter with a smaller margin of error before proceeding.

If your multi-meter is in working condition but you still do not get an ohm reading from the heating circuit, or your meter indicates a short to ground, the cable has apparently been damaged. We have rental tools to help locate the damage, and we have splice kits to repair the cable after the location of the damage has been determined.

Has any work been done in the area of the mat since the last time the heating circuit was tested? The cable may have been damaged where people have been working.

We have rental tools to help locate the damage in the floor.

We have Heating Cable Repair Kits once the location of the damage has been determined.

The cable was damaged during installation, it needs to be repaired.

If the location of the damage to the heating cable is known, you need a Heating Cable Repair Kit and the proper tools.

If the location of the damage is not known, we have rental tools that can help you find the damage.

Cable Fault Finder (Mat only)

Cable Fault Finder (for WarmWire)

Info sheet on ProTracer system.

Floor warming cable does not warm the floor.

Test the "line side" voltage at control from L1 to L2. Does it match voltage of mat?

Black and white power leads indicate a 120V mat.

Black and blue power leads indicate 240V mat.

Test the "load side" voltage output of the control while it indicates it is sending power to the floor. Is it sending out the proper voltage?

Black and white power leads indicate a 120V mat.

Black and blue power leads indicate 240V mat.

If the control indicates a GFI trip, it will not send power to the floor. Reset the GFI by turning it off, then turn it back on. If it trips the GFI again.

The control may be mis-wired. Check the wiring diagram on the back of the control. The cable may be damaged. Test the mat(s) for a short to ground with a digital ohmmeter as described in our installation manual. If your meter detects a short circuit, call the manufacturer. If your ohmmeter does not detect a short to ground.

  • The cable may have a very high resistance short that can't be detected with a standard ohmmeter. Try to locate a Mega ohmmeter or a Hipot Tester and call the manufacturer for Technical Support to determine if the insulation of the heating circuit has been damaged.
  • Test the function of the GFI in the control. Disconnect the heating cable(s) from the control and cap off the "Load side" control wires with wire nuts, or a similar method for safety. Try turning on the control again, if it still trips the GFI without being wired to a floor warming system, the control is wired wrong or it is defective.

The control may have a floor limit temperature setting that is too low. Is the control flashing "floor limit" in the lower left corner of the display?

Factory default floor limit setting is 99°F, but may need to be set lower for laminate floor coverings and other similar floor covering materials.

The control may have been "bypassed".

Check the wiring diagram on the back of the control. Verify each of the wire connections is correct and you have 4 wire nut connections to the control (and a 5th wire nut connection for the ground wires).

Your control has the proper wire connections per diagram on back, but your multi-meter shows full line voltage on the "load side" of the control when you believe it should not be sending power to the floor.

If it is a programmable control, there may be an error in programming.

  • Refer to the instructions for your control to verify all of your cycle times are programmed correctly and all cycle times for each day fall between 12:05AM and 11:55PM, in a logical progression throughout the day.

The contactors in the control may be locked in the "On" position.

The control will have to be replaced.

There may be a problem with the floor temperature sensor itself, or it may not be in the proper location.

Test the sensor with a digital multi-meter able to test up to 20,000 ohms (20k ohms) as described in our installation manual. Is it in proper resistance range for the present floor temperature? If it is not, call the manufacturer.

Minor damage to the outer jacket of a cable does not always require a Heating Cable Repair kit. Simply testing the cable with a digital ohmmeter will not always detect damage that has occurred to the heating circuit or the insulation on the heating elements. If you have access to a Megohmmeter or a Hipot tester, these tools can give you a quick pass or fail test of the heating element insulation. Please call us before attempting to use this type of equipment on any of our floor warming cables. When you don't have a Megohmmeter, there are additional tests that can be performed without a complete set of professional diagnostic tools. You can use the thermostat control as a test tool with the floor warming cable by running a brief "Power Test". DO NOT BYPASS the CONTROL to perform a "Power Test", it can cause personal injury or irreversible damage to the floor warming system.

Please Note: If part of the floor warming cable is still on the spool or part of the mat is still rolled up, you can't perform a Power Test. It would very quickly overheat the floor warming cable. The floor warming cable does not have to be fully imbedded in mortar to run this test, but be sure to remove sheets of cardboard or any other material being used to protect the cables from traffic during installation. The control, sensor and floor warming system are wired up in the normal fashion, and then turned on. Make sure there is a demand for heat so the control will send power out to the floor warming cable.

If the Power Test does not result in a GFCI trip, but the exposed cable does not seem to be warming, the heating circuit may have been damaged and the use of line voltage may have caused the heating circuit to burn out where the cable was nicked or crushed. Additional testing will be required.

  • Re-test the ohm value of the heating cable. Disconnect the power leads of the floor warming cable from the thermostat before performing this test. If your ohmmeter shows an open circuit now, or an ohm value out of this cable's resistance range, the cable will need to be repaired and possibly at the location where the jacket was damaged. We have Heating Cable Repair Kits, order number 81007142. Call the manufacturer for further information, or to place an order for a repair kit.
  • If the floor warming cable is within its specified Resistance Range, the control may not be sending out power to the cable. Ensure the control has a demand for heat, and use a digital multi-meter to test the "load side" voltage at the thermostat to see if it is sending out power to the floor. Verify the voltage reading matches the power requirements of this floor warming system.
  • If an AC amp meter is available, it is a quick and effective method of determining if any current is really going towards warming the floor. If your amp meter shows the cable is not drawing the proper level of current for this specific floor warming system, more diagnostic testing will be required to determine if the problem is with the heating circuit in the floor, improper voltage supplied to the system, or possibly something related to the thermostat control. If the amp meter shows the proper amp draw for this cable(s) it is generating heat. There may be something like moisture in the mortar bed or thick tiles, which can make it more difficult to detect heat being produced by the cable.

If the Power Test seems to be warming the cable and the GFCI in the control did not trip, it is then possible to further test the integrity of the insulation on the heating elements by applying tap water to the cable where the outer jacket has been damaged and soak it thoroughly. PLEASE NOTE: It is very important to take precautions to avoid electric shock BEFORE applying water to the cable. We strongly advise turning off the control and then turning off the circuit breaker before performing this test. After applying water to the damaged jacket of the cable, turn the breaker back on first, then turn the control on and turn it up to ensure the system is energized. NEVER touch a wet cable while it is energized, serious personal injury could result!

  • If the control continues to run without tripping the GFCI, the cable will need some drying time. Then a skim coat of an appropriate sealer can be applied to the damaged jacket for additional protection. You can use a thin layer of a 100% silicone sealant, or two or three coats of a heat rated "liquid electric tape" to re-seal the jacket. Let it cure fully before continuing with the installation.
  • If the GFCI in the control trips after water was applied to the damaged jacket, the insulation on the heating element(s) has been damaged and it will need to be repaired with a Heating Cable Repair Kit, order#81007142. You can ask your distributor if they stock our splice kits or call us and place your order.

Your Ohmmeter may be on the wrong scale, for instance, the 200k ohms scale measures up to 200,000 ohms, or 200k Ω.

The meter should typically be set on the 200 ohms scale (200 Ω) for testing cables with an ohm value less than 200 ohms. If your mat is outside the range on the nameplate label, call the manufacturer.

Some of our products have a resistance range above 200 ohms.

  • Set your ohmmeter on a scale that goes high enough to test the product you have. Many meters have a 2000 ohms scale, or 2k Ω. If your mat is outside the range on the nameplate label, call the manufacturer.

If the reading is a little high or low, test the meter itself.

Verify your meter is still working and properly calibrated by holding the test leads directly together to test the meter's "zero reading", often reading about 0.1 to 0.4 ohms. A reading of "OL" (open line, or over limit) is not the same as a reading of 0.1 ohms.

  • If your meter does not pass the calibration test with a zero reading of significantly less than 1 ohm, one of the test leads might be damaged or the meter itself may be damaged and would need to be replaced. If this is an older meter, it may need new batteries. If you can't get your meter to pass this calibration test, try to find a multi-meter with a smaller margin of error before proceeding.
  • If your ohm reading for the heating circuit was just a little high, the "zero reading" from your ohmmeter can be subtracted from your heating circuit ohm value. If the mat still is not within its ohm range, call the manufacturer.

Resistance readings for WarmWire cables must be taken from just one cable at a time. Is it possible more than one cable may have been wired together in series or in parallel?

Verify you are testing only one floor warming cable, and test it directly from its factory installed power leads.

Your ohmmeter may not be set up properly, or it may have a problem with one of the test leads, or it may simply need new batteries.
The ohmmeter must be set on the proper scale to test the heating circuit, typically the 200 Ω scale for a cable with a resistance range below 200 ohms.

Test the ohmmeter itself. Verify your meter is still working and properly calibrated by putting the two leads directly together to test the meter's "zero reading", often reading about 0.1 to 0.4 ohms. A reading of "OL" (open line, or over limit) is not the same as a reading of 0.1 ohms.

  • If your meter's calibration does not pass this zero reading test, one of the test leads made be damaged or the meter itself may damaged and would need to be replaced. If you are using an older meter, it may just need new batteries.
  • If the zero reading from your meter is not significantly less than 1 ohm, try to obtain a multi-meter with a smaller margin of error before proceeding.

If your multi-meter is in working condition but you still do not get an ohm reading from the heating circuit, or your meter indicates a short to ground, the cable has apparently been damaged. We have rental tools to help locate the damage, and we have splice kits to repair the cable after the location of the damage has been determined.

Has any work been done in the area of the floor warming cable since the last time the heating circuit was tested? The cable may have been damaged where people have been working.

We have rental tools to help locate the damage in the floor.

We have Heating Cable Repair Kits once the location of the damage has been determined.

If the location of the damage to the heating cable is known, you need a Heating Cable Repair Kit and the proper tools.

If the location of the damage is not known, we have rental tools that can help you find the damage.

Cable Fault Finder for WarmWire

Info sheet on the ProTracer system.

Test the "line side" voltage at control from L1 to L2. Does it match voltage of the cable?

Black and white power leads indicate a 120V cable.

Black and blue power leads indicate 240V cable.
Test the "load side" voltage output of the control while it indicates it is sending power to the floor. Is it sending out the proper voltage?

Black and white power leads indicate a 120V cable.

Black and blue power leads indicate 240V cable.

If the control indicates a GFI trip, it will not send power to the floor. Reset the GFI by turning it off, then turn it back on. If it trips the GFI again...
The control may be mis-wired. Check the wiring diagram on the back of the control. The cable may be damaged. Test the mat(s) for a short to ground with a digital ohmmeter as described in our installation manual. If your meter detects a short circuit, call the manufacturer. If your ohmmeter does not detect a short to ground...

  • The cable may have a very high resistance short that can't be detected with a standard ohmmeter. Try to locate a Mega ohmmeter or a Hipot Tester and call the manufacturer for Technical Support to determine if the insulation of the heating circuit has been damaged.
  • Test the function of the GFI in the control. Disconnect the heating cable(s) from the control and cap off the "Load side" control wires with wire nuts or a similar method for safety. Try turning on the control again, if it still trips the GFI without being wired to a floor warming system, the control is wired wrong or it is defective.

The control may have a floor limit temperature setting that is too low. Is the control flashing "floor limit" in the lower left corner of the display? 
Factory default floor limit setting is 99°F, but may need to be set lower for laminate floor coverings and other similar floor covering materials.

The control may have been "bypassed".

Check the wiring diagram on the back of the control. Verify each of the wire connections is correct and you have four wire nut connections to the control (and a fifth wire nut connection for the ground wires).
Your control has the proper wire connections per diagram on back, but your multi-meter shows full line voltage on the "load side" of the control when you believe it should not be sending power to the floor.

If it is a programmable control, there may be an error in programming.

  • Refer to the instructions for your control to verify all of your cycle times are programmed correctly and all cycle times for each day fall between 12:05AM and 11:55PM, in a logical progression through the day.

The contactors in the control may be locked in the "On" position.
The control will have to be replaced.

There may be a problem with the floor temperature sensor itself, or it may not be in the proper location.

Test the sensor with a digital multi-meter able to test up to 20,000 ohms (20k ohms) as described in our installation manual. Is it in proper resistance range for the present floor temperature? If it is not, call the manufacturer.

Minor damage to the outer jacket of a cable does not always require a Heating Cable Repair kit. Simply testing the cable with a digital ohmmeter will not always detect damage that has occurred to the heating circuit or the insulation on the heating elements. If you have access to a Megohmmeter or a Hipot tester, these tools can give you a quick pass or fail test of the heating element insulation. Please call us before attempting to use this type of equipment on any of our floor warming cables. When you don't have a Megohmmeter, there are additional tests that can be performed without a complete set of professional diagnostic tools. You can use the thermostat control as a test tool with the floor warming cable by running a brief "Power Test". DO NOT BYPASS the CONTROL to perform a "Power Test", it can cause personal injury or irreversible damage to the floor warming system.

Please Note: If part of the floor warming cable is still on the spool or part of the mat is still rolled up, you can't perform a Power Test. It would very quickly overheat the floor warming cable. The floor warming cable does not have to be fully imbedded in mortar to run this test, but be sure to remove sheets of cardboard or any other material being used to protect the cables from traffic during installation. The control, sensor and floor warming system are wired up in the normal fashion, and then turned on. Make sure there is a demand for heat so the control will send power out to the floor warming cable.

If the Power Test does not result in a GFCI trip, but the exposed cable does not seem to be warming, the heating circuit may have been damaged and the use of line voltage may have caused the heating circuit to burn out where the cable was nicked or crushed. Additional testing will be required.

  • Re-test the ohm value of the heating cable. Disconnect the power leads of the floor warming cable from the thermostat before performing this test. If your ohmmeter shows an open circuit now, or an ohm value out of this cable's resistance range, the cable will need to be repaired and possibly at the location where the jacket was damaged. We have Heating Cable Repair Kits, order#81007142. Call the manufacturer for further information, or to place an order for a repair kit.
  • If the floor warming cable is within its specified Resistance Range, the control may not be sending out power to the cable. Ensure the control has a demand for heat, and use a digital multi-meter to test the "load side" voltage at the thermostat to see if it is sending out power to the floor. Verify the voltage reading matches the power requirements of this floor warming system.
  • If an AC amp meter is available, it is a quick and effective method of determining if any current is really going toward warming the floor. If your amp meter shows the cable is not drawing the proper level of current for this specific floor warming system, more diagnostic testing will be required to determine if the problem is with the heating circuit in the floor, improper voltage supplied to the system, or possibly something related to the thermostat control. If the amp meter shows the proper amp draw for this cable(s) it is generating heat. There may be something like moisture in the mortar bed or thick tiles, which can make it more difficult to detect heat being produced by the cable.

If the Power Test seems to be warming the cable and the GFCI in the control did not trip, it is then possible to further test the integrity of the insulation on the heating elements by applying tap water to the cable where the outer jacket has been damaged and soak it thoroughly. PLEASE NOTE: It is very important to take precautions to avoid electric shock BEFORE applying water to the cable. We strongly advise turning off the control and then turning off the circuit breaker before performing this test. After applying water to the damaged jacket of the cable, turn the breaker back on first, then turn the control on and turn it up to ensure the system is energized. NEVER touch a wet cable while it is energized, serious personal injury could result!

  • If the control continues to run without tripping the GFCI, the cable will need some drying time, then a skim coat of an appropriate sealer can be applied to the damaged jacket for additional protection. You can use a thin layer of a 100% silicone sealant, or 2 or 3 coats of a heat rated "liquid electric tape" to re-seal the jacket. Let it cure fully before continuing with the installation.
  • If the GFCI in the control trips after water was applied to the damaged jacket, the insulation on the heating element(s) has been damaged and it will need to be repaired with a Heating Cable Repair Kit, order#81007142. You can ask your distributor if they stock our splice kits, or call us and place your order.

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.

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#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.

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 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°F (33 C), or about 10k ohms at 77°F (25°C), or up to approximately 20k ohms at 48°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.

Your Ohmmeter may be set on the wrong scale, for instance, the 200,000 ohm (200k Ω) scale.

Set your meter to the appropriate scale for the panel you have. For example, set on 200 Ω or the nearest equivalent on your meter, and retest.

If the ohm reading is a little high or low, test the meter itself by setting it on the 200 Ω scale or the lowest scale on your meter and hold the test probes directly together.

Verify your meter is still working and properly calibrated by putting the two leads directly together to test the meter's "zero reading", often reading about 0.1 to 0.4 ohms. A reading of "OL" (open line, or over limit) is not the same as a reading of 0.1 ohms.

  • If your meter calibration reading is significantly less than 1 ohm, your zero reading can be subtracted from your cable's ohm value. If the cable still is not within its ohm range, call the manufacturer.
  • If your meter's calibration does not pass this zero reading test, one of the test leads made be damaged or the meter itself may damaged and would need to be replaced. If you are using an older meter, it may just need new batteries.
  • If the zero reading from your meter is not significantly less than 1 ohm, try to obtain a multi-meter with a smaller margin of error before proceeding.

If your multi-meter is in working condition but you still do not get an ohm reading from the heating circuit, or your meter indicates a short to ground, the cable has apparently been damaged.

We have rental tools to help locate the damage, and we have splice kits to repair the cable after the location of the damage has been determined.

ProMelt cables must be tested individually, not after being wired together in parallel.

Verify you are testing only one ProMelt cable, and test it directly from the factory installed power leads. If it is not within the Resistance Range for your cable, call the manufacturer.

Did you use an analog meter with a needle that sweeps across the gauge?

The analog meters typically are not accurate enough to test the resistance value of our products. Measure the resistance of the cable again with a digital ohmmeter.

Is your snow sensor located where it is exposed to the weather and has been covered with winter precipitation?

If not, consider alternative locations for the sensor so it will be more likely to receive unobstructed precipitation.

Some of our ProMelt controls come with two sets of installation instructions. Be sure to use the set of installation instructions specifically intended for use with a Watts Radiant ProMelt system.

Each of our ProMelt Controls has a downloadable instruction manual.

Some of our ProMelt controls have an adjustable Trigger Temperature Range. Is the weather cold enough to require activation of the system with the "Trigger Temperature Range" (TT) as it is presently set in your control?

Refer to your ProMelt Control instructions sheets and see if your control has a TT set point circuit. Adjust as necessary for your climate and the heat output from your ProMelt system.

At times when the air temperature outside is too cold, some ProMelt systems may not be able to overcome the heat loss to the ground and air, or it may just take longer to melt the precipitation.

ProMelt systems are typically designed to provide 38 watts of heat per square foot, or as much as 50 watts of heat per square foot. If the temperature outside is too cold, your ProMelt system may not be able to create enough heat to overcome the heat loss to the environment at that time.

  • When the sun comes out or the wind slows down, try turning on the system manually and see if it is able to melt the snow/ice with somewhat milder environmental conditions.

Some of our ProMelt controls have a Low Temperature Cutoff (LTC) circuit, which prevents operation of the ProMelt system when the ambient temperature falls below 15°F. This is used to avoid wasting electricity when some ProMelt systems may not be capable of melting snow/ice during periods of extreme cold.

You can try disabling this circuit to see if your system can overcome the heat loss to the environment with that day's ambient temperature and environmental conditions.

ProMelt systems are typically designed to provide 38 watts of heat per square foot, or as much as 50 watts of heat per square foot. If the temperature outside is too cold, your ProMelt system may not be able to create enough heat to overcome the heat loss to the environment at that time.

No power is supplied to the ProMelt Control.

Test the voltage of the power supply line feeding the control and verify it is correct for this specific system.

Test the voltage on the output side of the ProMelt Control when you try to turn it on. Is it correct for the power requirements of your ProMelt system?

There are often two sets of instructions that come with the ProMelt controls, find all of the installation instructions that came with the control.

Be sure to use the set of installation instructions specifically intended for use with a Watts Radiant ProMelt system.

One of the wire connections inside the ProMelt control may have come loose or may not be wired correctly for your application.

Call the manufacturer.

Test the output voltage from the control with your multi-meter.

Is it sending out the proper voltage for this system?

  • Check the voltage rating of this ProMelt cable as shown on the factory ID tag on the system's power leads. Verify it matches the voltage coming out of the ProMelt control.

Does the proper voltage reach the factory power leads for this ProMelt cable?

  • Measure the voltage reaching the junction box containing the factory power lead connections for this ProMelt cable(s). Is the proper voltage reaching the power leads of the system?

Use an amp meter to determine if each ProMelt cable is pulling the proper amperage for the specific size of cable(s) you are working on.

They should be tested individually, one ProMelt cable at a time.

  • If your amp meter reading is not reasonably close to the factory specified amp rating for this specific ProMelt cable, gather all available information for your ProMelt system and contact the manufacturer.
  • If you don't know the amp rating for your ProMelt cable, gather all available information on the system and call the manufacturer.

At times when the air temperature outside is too cold, some ProMelt systems may not be able to overcome the heat loss to the ground and air, or it may just take longer to melt the precipitation. Some of our ProMelt controls have a Low Temperature Cutoff (LTC) circuit, which prevents operation of the ProMelt system when the ambient temperature falls below 15°F. This circuit is used to avoid wasting electricity when some ProMelt systems may not be capable of melting snow during extreme weather conditions.

You can try disabling the LTC circuit to see if your system can overcome the heat loss to the environment with that day's ambient temperature and environmental conditions.

ProMelt systems are typically designed to provide 38 watts of heat per square foot, or as much as 50 watts of heat per square foot. If the temperature outside is too cold, your ProMelt system may not be able to create enough heat to overcome the heat loss to the environment at that time.

  • When the sun comes out or the wind slows down, try turning on the system manually and see if it is able to melt the snow/ice with somewhat milder environmental conditions