SIT-820 repeated valve failure

[Kentia]

Hi,

I have a 2 year old Natural Gas fireplace, Mendota DXV 60, which uses a gas valve: SIT-820 NOVA mV, model 0820708.

In the last year the gas valve has failed 4 times. I have had it replaced, 4 times, by a Mendota authorized service provider. Neither the repairman nor Mendota can determine what the problem is. I'm told these valves should be trouble free for many years.

National Grid, gas provider, has investigated the gas supply and has not found any issues.

Failure detail:
the fireplace will be working fine and then I turn the main switch to the off position before going to bed. The next day, I turn the switch to the on position, no flame.
The pilot is still on, I turn the switch off, wait 5 minutes, turn the switch on, but no flame.
The repairman has done a series of tests and verified the millivolt readings and they're ok, except there is still no main flame.
He replaces the valve and the issue is resolved.

What conditions can cause this valve to fail?
The valve had to be replaced 4 times, this is costly.

I have other gas appliances: dryer, stove and 2 other fireplaces (different manufacturer), that do not have this problem.

I cannot afford to keep replacing the valve. Can you provide some assistance to help resolve this issue?

Thanks.

[natgastech]

Valve failure is rare and based on our numbers less than 1% of our service calls. If a new valve is installed and is still not working properly the technician has made a mistake. You should definitely stop paying for incompetence. If someone knows statistics they could tell you how crazy unlikely it is for 4 valves to fail based on a 1% failure rate. Anyway, your problem is an intermittent short or bad connection in the thermopile or switch and wires.

[hearthman]

Site rules prohibit discussing troubleshooting but be advised there are many things to try and many things that could be causing this. Up to now, all we've heard is about the valve. As NGtech points out, you have the switch leg, thermopile, wiring and connectors and possibly a high limit switch. Other outside sources might be a 110vac wall switch, which would fry a new valve.

Sounds like you still haven't gotten the right pro in there. What area do you live in?
Hearthman

[Kentia]

Thanks for the quick replies.
I live near the Boston, MA area: Waltham.

Thanks.

[paulc]

Site rules prohibit discussing troubleshooting but be advised there are many things to try and many things that could be causing this. Up to now, all we've heard is about the valve. As NGtech points out, you have the switch leg, thermopile, wiring and connectors and possibly a high limit switch. Other outside sources might be a 110vac wall switch, which would fry a new valve.

Sounds like you still haven't gotten the right pro in there. What area do you live in?
Hearthman

Hi I'm a boiler installer helping a friend out and have the same valve in a yotule stove 820 SIT NG I can't get the pilot to stay lit, I wait the 60 sec and longer put a new thermopile and thermocouple in and still the same thing, I have good flame and even held a lighter under the thermopile, I don't own a tester that does milivolts.
Lastly I changed the valve as a last resort and still the same thing, there isn't much left, no damper, direct vent through the chimney (sleeved) no thermostat just the on and off switch.
I know you can't give advise like you said earlier but if you can give me a clue what I'm missing that would be greatly appreciated sounds like you know what your talking about.
Thanks Paul Email Address Removed

[hearthman]

Paul sorry but Site Rules prohibit DIY advice in these public forums. Get your post count up and apply for Pro membership so you can post and get technical advice in the Pro forums.

Also, Site Rules prohibit posting your email addy into your posts as BOTs can find it and wreak havoc so it will be deleted. If its in your profile, that is all you need.
Thanks and sorry,