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Gas valve not opening consistently -- gas HWH

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I've been having a problem with gas HWH for past 2 years. This is a HWH with a powered vent and a White-Rodgers intellivent control valve. The problem is that the solenoid won't reliably open when the HWH goes through its startup cycle when it calls for heat (fan on, ignitor on, solenoid power on, etc.). Often the HWH will go through 1 or 2 startup cycles and the valve will open on the third try. When that doesn't work and the controller shows a fault, I've found that if I cycle the power, a few taps on the solenoid when it clicks during the startup cycle generally convinces the valve to open, but more recently even this has not been sufficient.

Interestingly, this had historically seemed to be a problem when outside temperature goes from cold to warm or vice versa. But over time, it has become a more consistent problem.


I've recently disconnected the gas feed line to look for any obstructions and the inlet to the valve looks clean (the screen is clean). Coincidentally, it seemed that this operation (disassembly / reassembly) allowed the valve to work. Subsequently, when the problem recurs, turning off the gas supply and allowing the solenoid to turn on with zero "head" pressure seems to allow the valve to open. I've only done this a couple times so this is not quite verified as a "fix". My 3 questions for the experts on this forum 1) is this likely as simple as a bad / worn out solenoid and can I replace that without replacing the whole valve/ control panel? Note that the HWH is ~ 10 years old so arguably nearing its end of life and I don't want to spend $300 to repair a HWH that might start leaking in a few years. 2) Is there a chance that low / high gas pressure could be at play here? I have not measured it (yet), but note there is a gas fired furnace adjacent to this which has never had issues. The fact that relieving head pressure allows the valve to open makes me think this could be a factor. 3) is there any way to lubricate the valve / solenoid to make it more reliable? I'm hesitant to spray anything inside the valve for fear of making it worse.

And if there are other ideas, I'd love to hear them. I am a very handy homeowner but do not pretend to be an expert in plumbing or HVAC. Thanks in advance!

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,426
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    My bet would be a sticky solenoid. They do. Try this: next time it doesn't work, have a persuader -- I'd suggest a screwdriver with a soft handle -- handy and give the solenoid a tap (you're not trying to hit a homer, but you are trying to get its attention) with the handle of the screwdriver. If it's the solenoid or something sticky in the gas valve actual valve, that may open it --- and tell what the problem is (though not how to fix it).
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mattmia2
    mattmia2 Member Posts: 9,735
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    Is this powered from some sort of 120v ac supply or from a pilot generator?
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,609
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    You need someone to troubleshoot it or replace the water heater.

    It could be the gas valve, it could be a pressure switch or a sticking control it could be a pressure switch on the vent.

    It could be 100 things but guessing won't likely fix it unless you get lucky
    Larry Weingarten
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,329
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    Hi @hardycm , Years ago the control manufacturers changed the screws on their controls to tamper resistant types, so nobody would play with the controls. On old controls, the solenoid or magnet was easy to unscrew and clean. Not so now. In your shoes, I'd first have a look at the anode in the tank. If there is plenty left, suggesting that the tank is not about to fail, then I'd replace the control (and anode). If the anode is largely used up, start shopping for a new heater. The safety concerns are just too great otherwise.

    Yours, Larry
    HVACNUT
  • hardycm
    hardycm Member Posts: 2
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    Thanks for the replies so far. This pretty much confirms my thinking. -- Jamie, yes I'm betting a sticky solenoid and the screwdriver trick is exactly what I've done. Ed -- I have been troubleshooting it enough to confirm that when power is supplied to the solenoid, I'm not getting gas through the valve. Question is why, and what I might do about it. What I hear from Larry is that this likely isn't a user serviceable part and I have to change out the whole thing. Then it becomes a gamble as to how much longer the tank will last. Matt -- it is supplied by 120 VAC.
  • HVACNUT
    HVACNUT Member Posts: 5,861
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    You really should be checking manifold pressure when the gas valve gets powered. That will tell you right away which direction to go. Gas pressure good (as rated on the valve), go toward the burner. Low or no pressure, go to the gas valve and inlet pressure.