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Gas stove wont light

Post in 'It's a Gas!' started by JimK24, Mar 15, 2010.

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  1. JimK24

    JimK24 New Member

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    I have a Vermont Casting gas stove with a Honeywell VS8420 valve on it. The pilot lights fine. When I turn the knob from "Pilot" to "On", I hear a clunk and the pilot goes out.

    I'm getting about 27 mV at the tip of the thermocouple. I'm getting about 700+ mV at the Thermopile (between TP and TPTH). My coil resistance between TP and TH is 3.5 Ohms. I cleaned everything up but haven't been able to fix the problem.

    At first I thought maybe I had a bad thermocouple or thermopile, but my mV readings are good.

    Any ideas?

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  2. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    Loc:
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    Chesk to see if there's a spill switch located near the top of the stove.
    If there is one, it may have failed or the sheathing on the wiring to it
    may have deteriorated, exposing the copper core & causing a short.
    HTH.
  3. Wood Heat Stoves

    Wood Heat Stoves Minister of Fire

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    http://woodheatstoves.com/-p-12685.html

    i just uploaded the book for you, see page 7 of the free pdf.....for the rest of the tests



    is the unit b-vent? if so it might have a spill switch as mentioned above,
  4. JimK24

    JimK24 New Member

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    Thanks for the info. I jumpered out the spill switch. Same results, pilot goes out when turning knob on.

    Another interesting note - when I jump TH to TPTH (with the pilot lit and the knob in the pilot position) I can hear the typical valve click, just like when it used to light. When I jumper it it clicks, when I take the jumper off it clicks again - but the burner doesn't light.

    Any ideas?
  5. Wood Heat Stoves

    Wood Heat Stoves Minister of Fire

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    what were the results of the other valve tests listed in the pdf i posted??
  6. JimK24

    JimK24 New Member

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    Loc:
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    Test A (coil resistance): 3.2 - 3.3 ohms
    Test B (thermopile): 530 mV
    Test C (thermocouple): 27 mV
    Test D (operator pull in): couldn't test because operator would not pull in
    Test E (resistance system): did not test. I didn't think this was relevant because I can not even turn the knob to "On" without the pilot going out.

    Thanks.
  7. Wood Heat Stoves

    Wood Heat Stoves Minister of Fire

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    sounds like its time to call a vc/monesson dealer for a new valve...
    i'd call the factory first to confirm, but sounds like a bad valve

    i dont have much experience with honeywell valves
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