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  1. #1
    Join Date
    Feb 2009
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    19
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    Do SIT valves leak??

    Greetings. Before beginning, thank you for all the advice and help!!

    We have a coal effect gas set which uses a SIT 820.640 control/valve. Generally we can't see below the coal tray when in operation but I happened to be watching TV lying on the floow and saw flame between the coal tray/burner and the top of the valve. I shut everything down, pulled everything but the basic valve/coal tray out to test. The unit fired normally and after about 60 seconds (after a cold start) flame appeared behind the unit and between the value/controller and the tray. I shut down and restarted, the flame then appeared immediately upon ignition. I allowed the unit to cool completely and it went back to a 60 second delay after the tray burner ignites. It appears that heat expansion is creating a gap for gas to escape.

    SO (as a naive homeowner), I'm sort of stunned that this occurred and I happened to catch it. Usually this valve/controller is hidden and we turn the fireplace on/off with a wall switch. Seems like house fire waiting to happen.

    So here's the question. Although I guess it could be piping, as I can't see the back of the unit, I'm going to replace the valve. I've been looking around and can only find used 820.640's. I suspect it's been discontinued. Does anyone know of an equivalent?

    thank you!!

  2. #2
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    7,210
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    Valves all have a tiny allowable leakage per ANSI stds. However, fugitive gas igniting outside the combustion chamber is a hazard. Shut down the fireplace until a pro can diagnose and correct the problem. Gas valves can be quite specific and should only be replaced with OEM supplied or approved units. This is NOT DIY work. Hire a pro before someone gets hurt, please.

  3. #3
    Join Date
    Feb 2009
    Posts
    19
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    Thread Starter
    Hearthman, Thanks for the insights. So today I finally was able to hook up a longer gas supply to the SIT valve which allow me to test it with the unit turned around. Again, after warming up for about a minute, I saw the secondary flame igniting along about a 1" section of the back edge of the brass cover plate on top of the valve. Seems the gasket between that cover plate and the valve body has failed. I couldn't spend any more time on it today, but in the next couple days I will pop that cover off and see whether it is uses and actual pre-formed gasket, or they used some type of heat proof gasketing material. If that doesn't work, I'll replace the valve.

  4. #4
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    7,210
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    Dude you need to step away and quite playing junior mad scientist. You are waaay over your head and about to get hurt. You are also exposing anyone who lives there or could enter your home, such as fire fighters to undue hazards, which could put you in jail should someone get hurt.

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  6. #5
    Join Date
    May 2004
    Posts
    13,464
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