Heated floor tripping GFCI thermostat

[kbsparky]

I have a customer with a bathroom with the warm tiles heating system installed in one of his bathrooms.

After about a year in operation, the built-in GFCI on the thermostat began tripping. Initially, resetting the unit would work for awhile, but later it would not set at all. The system operates at 120 Volts, but the thermostat is capable of using either 120 or 240 Volts.

Without busting up the floor and installing a new system, how would one troubleshoot and repair such an installation?

We decided to install an isolation transformer downstream of the thermostat, change the circuit and thermostat to 240 Volt input, and wired the transformer for 240 input, 120 output.

This scenario has worked fine since the installation of the transformer. No more nuisance tripping.

Have any of you utilized this solution for this type of problem?

 

[brian john]

NO I contacted the manufacture and they sent me a test kit, the kit has two different settings open cable and short. When using the kit the spot of the issue heats up, utilizing an IR camera we have pinpointed the cable issue. The tile vendor pulled up the one tile and a repair kit was utilized.

 

[ty]

I have a customer with a bathroom with the warm tiles heating system installed in one of his bathrooms.

After about a year in operation, the built-in GFCI on the thermostat began tripping. Initially, resetting the unit would work for awhile, but later it would not set at all. The system operates at 120 Volts, but the thermostat is capable of using either 120 or 240 Volts.

Without busting up the floor and installing a new system, how would one troubleshoot and repair such an installation?

We decided to install an isolation transformer downstream of the thermostat, change the circuit and thermostat to 240 Volt input, and wired the transformer for 240 input, 120 output.

This scenario has worked fine since the installation of the transformer. No more nuisance tripping.

Have any of you utilized this solution for this type of problem?

It sounds like there is leakage current (presumably from a bad spot in the heat wire).

Brian John's method is probably what you should have done.

Let me ask, do you still have GFCI protection on the secondary side of your isolation transformer?

 

[480sparky]

...........Brian John's method is probably what you should have done...........

I've heard some manufacturers have equipment they rent you to locate a bad spot. I've never had to find one, so I don't know for sure if this is true.

 

[Cow]

It sounds like KBSparky took the ground fault protection out of the circuit with the transformer. That sounds like a work around fix rather than the proper solution.

Contacting the manufacturer would of been my first step. They make the product, they should know how to troubleshoot and repair it properly.

 

[Thirst4Knowledge]

I have a customer with a bathroom with the warm tiles heating system installed in one of his bathrooms.

After about a year in operation, the built-in GFCI on the thermostat began tripping. Initially, resetting the unit would work for awhile, but later it would not set at all. The system operates at 120 Volts, but the thermostat is capable of using either 120 or 240 Volts.

Without busting up the floor and installing a new system, how would one troubleshoot and repair such an installation?

We decided to install an isolation transformer downstream of the thermostat, change the circuit and thermostat to 240 Volt input, and wired the transformer for 240 input, 120 output.

This scenario has worked fine since the installation of the transformer. No more nuisance tripping.

Have any of you utilized this solution for this type of problem?

did u try a replacement t-stat g.f.i combo first?? ive seen them go bad.

 

[ivsenroute]

I would do resistance checks and compare them to the manufacturer's specs. The last one I installed in 2008 came from the factory with a label that stated an ohm range.

After verifying the stated or calculated ohm range, I would meg out the system. If it was a bad tile install you can easily have a shorted wire where a tile has cracked or the grout has failed.

 

[dbuckley]

Even a proper isolating transformer (ie no ground connection at all on the secondary) sounds a risky proposition to me; clearly one part of the heat wire has lost insulation and is leaking to ground through the tiles. If another fault develops then there is the possibility of unprotected step potential between tiles.

I would guess (but have no practical experience to back it up) that with the floor energised you could find the probable faulty tile with a meter probe, simply prod each tile with a meter probe, with the other probe connected to one end of the transformer, looking for the highest voltage. Do it from each end of the transformer winding and see if the location agrees. With a digital meter you may need a shunt resistance across the meter to get its input impedence down from many megohms to a few kilohms.