Anyone have an idea of the cause of this....

[emahler]

We were called out to a restaurant this afternoon, for a problem with their water heater.

They have a gas fired WH, with 120V power feeding an automatic damper for the exhaust.

Whoever installed this, put a GFCI receptacle in to power the damper.

The water heater was installed in June. Worked fine until Friday night.

Friday night, it tripped the GFCI. They had a plumber out yesterday, couldn't find anything wrong. Reset the GFCI. Plugged in the damper, worked fine.

GFCI tripped again last night. They temp plugged the unit into a non-GFCI circuit. We got out there today, GFCI reset no problem, plugged in the damper, turned up the t-stat. Everything worked like a charm. Checked the control box, nothing burned up, no noticable issues. Circuit board looked fine.

Anyone have any ideas why it would suddenly trip the GFCI.

[Oakey]

My guess..Bad gfi? Install a single receptacle maybe instead

[iwire]

Install a single receptacle maybe instead

If it happens to be in the kitchen that will be a violation.

[emahler]

that's what we did. But I haven't come across this before, and just wondering if anyone knew what a possible cause was. I wasn't there, it was one of our techs, so I am going on what he told me.

[bphgravity]

A ground-fault is occuring that exceeds 4-6 mA. I agree with Bob that replacing this receptacle outlet with a non-gfci protected one would be violation of the code.

[jeff43222]

My guess is that the GFCI circuitry could have worn out from all the surges from the on/off cycles of the damper. The other possibility is that you have an actual ground fault somewhere in the circuit or in the damper.

But a new GFCI shouldn't wear out so fast, so I'd be inclined to think there's a ground fault. Break out your tracing gear and starting looking for it.

[DaveTap]

LOL... They had a plumber out to check an electrical problem? Typical

Please tell me the damper is correctly installed to prevent the water heater from firing if the damper isn't open.

What brand/model damper and was the damper open, closed or in travel when GFCI tripped? Also how cold was it outside?

[i2rservices]

I have seen GFCI's go bad but usually after they've been in use for some time. I would make sure all the wiring is "tight" to it, as I imagine you've already done that. Also, I have seen where a strong "RF" signal will trip them as well. Make sure they are grounded well and one thing to check is for some RF radiating devices nearby.

[emahler]

a little update. heater wasn't in the kitchen, it was in a utility closet that was only accessible from the outside. No water (sinks, spigots, etc) in the closet except the water heater.

we went back this morning to check it out -
Dedicated circuit - checked both ends- everything tight. The only thing plugged into the outlet was the water heater. We were able to run it through it's paces, no problems. Worked like a champ. We did this yesterday as well, while still plugged into the GFCI and had the same result.

We checked the connections in the control box, the sensors and the damper. No problems. No leakage to the damper, duct, or water pipes.

No reasonable explanation for the GFCI to trip. So we left them with a single receptacle and a working water heater. We are in this restaurant fairly often, so we'll just keep an eye on it.

I'm leaning towards bad GFCI or possibly something to do with moisture. But nothing definative could be found.

[jeff43222]

Any chance there was a N-G short in a damaged wire somewhere along the line? I've seen a few of those recently. Things worked fine on a regular circuit, but tripped a GFCI.

[emahler]

not after the GFI. and nothing showed up before the GFI. it's EMT straight back to the panel. I'm telling you, alot of years worth of experience in our company looked at this, and no one has a definative reason.

might just be one of them x-file problems.

[charlie k.]

Just out of curiousity, does this unit have an electronic igniter or a standing pilot? If it is an electronic igniter thats your problem. Put it on a regular (non-gfi) circuit.
Charlie

[emahler]

honestly charlie, i'm not sure. but why would the electronic ignitor work fine for months, and now trip the GFCI?

BTW- we put it on a single receptacle - no gfci, works fine.

[charlie k.]

Dirt and byproducts of combustion can be conductive and will cause the gfi to trip. You can clean the insulator on the igniter but it will happen again.
Charlie

[emahler]

ok. good to know. we've never seen this before. usually, most water heaters/dampers/circ pumps are either hardwired or single receptacles. Only recently are we starting to see them on GFCI's.

[DGrant041]

Dirt and byproducts of combustion can be conductive and will cause the gfi to trip. You can clean the insulator on the igniter but it will happen again.
Charlie

Hey that sounds similar to someone that had a problem with an igniter on a gas fire place in the bedroom. It tripped the afci from day one. I think they ended up replaceing the igniter.

If it isn't the igniter, I would vote for the moisture situation--either in the motor or the control circuit. That's something that won't be there when you first plug it in but would be there after the water is hot. Also, motors and insulation degrade over time.

Please keep us posted when you find out--I hate not knowing what the answer is (was). :confused: