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Sit 820 gas valve kicks on when touched

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dynastyss
dynastyss Member Posts: 14
in Gas Heating
Hello!

So two times now the direct vent millivolt fireplace should have been on, thermostat on, and failed to fire. Thermocouple and thermopile are showing consistent and good voltage. The only common denominator is when I go to jiggle or touch the sit 820 gas valve it instantly roars on and works for a couple days. Rinse and repeat.

I tested and it is showing 2.4 ohms. But could it still be failing or on the way out? Any other way to test it?

Thanks

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  • Bob Harper
    Bob Harper Member Posts: 1,035
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    Disconnect the stat and run it off a jumper. If it fails to fully ignite the burner within 4 seconds that is considered a delayed ignition and a safety issue. Post your millivolt readings. Also, what is the static and burning inlet gas pressure and manifold pressure on high? This is most reliable valve I've ever seen.
    What make & model fireplace?
    Here are troubleshooting guides from SIT:
    http://www.gdainfo.com/Resource1049853HJDUFOS023X/Touble Shooting/SIT Millivolt Valve Troubleshooting Guide.pdf
    http://www.sitgroup.it/wp-content/uploads/2017/09/820-mV-GB.pdf
    http://rs.woodmanspartsplus.com/company_41/820 instructions.pdf
    dynastyss
  • dynastyss
    dynastyss Member Posts: 14
    edited December 2017
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    > @Bob Harper said:
    > Disconnect the stat and run it off a jumper. If it fails to fully ignite the burner within 4 seconds that is considered a delayed ignition and a safety issue. Post your millivolt readings. Also, what is the static and burning inlet gas pressure and manifold pressure on high? This is most reliable valve I've ever seen.
    > What make & model fireplace?
    > Here are troubleshooting guides from SIT:
    > http://www.gdainfo.com/Resource1049853HJDUFOS023X/Touble Shooting/SIT Millivolt Valve Troubleshooting Guide.pdf
    > http://www.sitgroup.it/wp-content/uploads/2017/09/820-mV-GB.pdf
    > http://rs.woodmanspartsplus.com/company_41/820 instructions.pdf

    Thanks Bob. So I get 500 milli with the fireplace on and around 300 with just the pilot on.

    I just attached a photo of the valve which shows the current settings.

    It is a hearthstone luno 8160

    The odd thing is it lights up super quickly. Will work wonderfully for a few days or weeks then recently has just stopped working. Won't work until someone touches the valve and it magically works again.
  • ratio
    ratio Member Posts: 3,626
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    Is it a "lay a finger on the side of thew valve" touch, or is it "grab the wires and wiggle" touch? It sounds more like a poor connection on the wiring, especially if you physically move anything—even a little. remove & reinsert the wires, or loosen & tighten the terminal screws a few times. If it's a loose\oxidized connection on the valve, that should make it go away, at least for some time.
    dynastyss
  • Jamie Hall
    Jamie Hall Member Posts: 23,286
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    If it's lay a finger type stuff, I'd bet on a bad ground. Either way, the first thing I'm looking for here is a weak connection. It may look good, but it may not be good.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    dynastyss
  • dynastyss
    dynastyss Member Posts: 14
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    It is in fact more lay finger on it material. I unplugged all the leads on the th, tp, th/tp side when testing the ohms. I didn't even realize there is a ground. What would be a good way to clean that up?

    Thanks
  • Jamie Hall
    Jamie Hall Member Posts: 23,286
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    The first place I would look is for the grounding of the whole thing -- which includes the gas valve -- to the switchboard in your house. There should be, somewhere, a solid neutral wire going to the switchboard (it should be a white wire) and there should also be a solid ground (which should be green). If there is no 110 volts it still needs a ground -- the green wire -- but not the white. It may not have one.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    dynastyss
  • Bob Harper
    Bob Harper Member Posts: 1,035
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    The center terminal, TP, is the ground. Make sure all the terminals are intact by wiggling each. Note there is another set of spade connectors 90 degrees below the visible ones. Look up under the operating head and you'll see those male spade connections.
    dynastyss
  • BobC
    BobC Member Posts: 5,478
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    Also make sure that knob is actually in it's detent, it may just be on the edge.

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge

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