Tech Tips: Troubleshooting a GFI Issue
Troubleshooting a Radiant Heat System GFI Issue
When you’ve installed a thermostat for a heated flooring system, if you see “GFI” displayed on the screen, that means that there may be a ground fault in the system. If you have a GFCI breaker that could be the cause, and it could also be because there is resistance between the wire and the ground. Testing for a ground fault is done by using a digital ohmmeter to see where ohms are coming from, and if there is any read from the black wire to the ground or from the red or yellow wire to the ground, you’ll need to fix the issue. In this video, you’ll learn how to test for and troubleshoot a GFI issue.
If your thermostat displays
GFI on the screen, it's telling you that it think its sees a ground fault. That
ground fault sometimes is in the wire that's coming up from the roll or the
system in your floor. Sometimes it's because you have a GFCI protected circuit
breaker in your circuit breaker box. One important thing to remember is if you
have a GFI circuit breaker in your box and you have a GFI controller in your
thermostat, those two could fight one another. The idea is our thermostats have
GFIs built into them so you do not need a GFCI protected breaker.
If you have a GFI problem, give us a call and
we can send you this sheet. This is the ohms reading guide. This will tell you
how to do the test on the cable. Today we're just going to talk real quickly on
how to do it in real life. To do this all you're going to need is a digital
ohmmeter. On this digital ohmmeter, we want to see if we're getting ohms across
these two resistance wires and if we're getting resistance between the
resistant wire and the ground or the other resistance wire and the ground.
The simple test is put the probes on the
yellow and black. This is yellow and black because this system is 120. If this
were 240 it would be red and black. We should be getting ohms here. We should
not be getting ohms from the yellow or red wire to ground. You want to see if
your ohmmeter giving you any ohms readings. It should be displaying OF or a
one or INF. You should not be getting any ohms numbers across this. The same
with the black to ground. These numbers should be INF, OFF or just a 1 displaying.
To
recap, you don't want any reading from the black wire to ground or from the
yellow or red wire to ground. That's how you troubleshoot a GFI issue with the
WarmlyYours system.
