Floor Heat problem

[Greg1707]

I am having a problem with a Nuheat floor mat and thermostat. I have installed these systems several times before with no issues. We installed the six by eight mat, 120 volts and followed all of the procedures and verified ohms before during and after. All was okay. We installed the thermostat and started it up. It went through a check list and indicated all systems go. The thermostat then had a prompt to push the GFCI test button. I pushed the button as instructed and there was a loud pop and spark within the thermostat.

The thermostat continued to light up (was not destroyed). I removed the thermostat and checked for any sign of arcing. There was no smell or burnt or melted wires etc. Now the big problem. I re checked the ohms etc. and now have continuity between the line to neutral as well as line to ground and neutral to ground. It is as if something shorted out in the thermostat and fried the wires on the floor mat.

Could it be the thermostat was missing an internal electronic component? Any ideas about this problem?

 

[kwired]

I am having a problem with a Nuheat floor mat and thermostat. I have installed these systems several times before with no issues. We installed the six by eight mat, 120 volts and followed all of the procedures and verified ohms before during and after. All was okay. We installed the thermostat and started it up. It went through a check list and indicated all systems go. The thermostat then had a prompt to push the GFCI test button. I pushed the button as instructed and there was a loud pop and spark within the thermostat.

The thermostat continued to light up (was not destroyed). I removed the thermostat and checked for any sign of arcing. There was no smell or burnt or melted wires etc. Now the big problem. I re checked the ohms etc. and now have continuity between the line to neutral as well as line to ground and neutral to ground. It is as if something shorted out in the thermostat and fried the wires on the floor mat.

Could it be the thermostat was missing an internal electronic component? Any ideas about this problem?

Was the heater leads disconnected from the controller when making this last test?

Was proper voltage being applied? 240 volts to a 120 volt heater would not be a good thing.

 

[Greg1707]

voltage correct

voltage correct

Yes, the voltage was correct. I re checked the reading with the thermostat disconnected.

 

[GoldDigger]

If a 120/240V load was connected with its neutral connected to the feed through terminals of a GFCI, the fact that the GFCI interrupts the neutral as well as the hot could have caused an overvoltage on a 120V part of the load.
Pretty unlikely, but worth ruling out.

 

[Dennis Alwon]

If a 120/240V load was connected with its neutral connected to the feed through terminals of a GFCI, the fact that the GFCI interrupts the neutral as well as the hot could have caused an overvoltage on a 120V part of the load.
Pretty unlikely, but worth ruling out.

I have never seen a floor mat that was 120/240. They are either 120V or 240V depending on what you order. The gfci is built into the T-stat/timer.

 

[GerryB]

Can you feed the heat direct to see if it's ok, hopefully it is just the stat. Also they have pretty good tech support, I guess I would call them first.

 

[RLyons]

I did troubleshooting 2 separate times on a incorrectly installed system through their customer service. It was awhile ago but the actually sent the troubleshooting equipment to the distributer and the homeowner had is waiting for me when I arrived. Came with a megger, Full FLIR camera and some crazy machine that actually fused the break and applied voltage to the cables to aid the FLIR in locating the break. They did this 2 separate time for the same person and it was because the tile installer had a poor tile mix and notch trowel mortar directly over the cables.