Mat

Ohm value does not match range shown on ID tag.

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 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.

Not getting an ohm reading from the heating circuit

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.

• Cable Fault Finder
• ProTracer system
• Heating Cable Repair Kit instructions
• Heating Cable Repair Tool Kit

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.

• Cable Fault Finder
• ProTracer

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

• Heating Cable Repair Kit instructions
• Heating Cable Repair Tool Kit

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.

Heating Cable Repair Kit instructions

Heating Cable Repair Tool Kit description.

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

Cable Fault Finder (for Mat or for WarmWire)

Info sheet on ProTracers.

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 back of 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 ohm meter 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 degrees F, but may need to be set lower for laminate floor coverings and other similar floor covering materials.

Mat keeps heating floor after it should stop heating.

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 12:05 AM and 11:55 PM, 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.

The floor warming cable's outer jacket has been scraped or mildly damaged. It looks like only the outer jacket is damaged, the cable still tests within range with a digital ohmmeter, and shows infinite resistance to the ground wire. Does it need to be repaired?

Minor damage to the outer jacket of a cable does not always require a Heating Cable Repair kit, but 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 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 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 number 81007142. You can ask your distributor if they stock our splice kits or call us and place your order for one.

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 Watts Radiant, 800-276-2419. 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.