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direct vent

STEAM DOCTOR Member Posts: 1,368
Went to a job today. Customer has two ao smith direct vent hot water heaters piped in series. Customer says that one of them blows out on a regular basis and needs to be re lite. From the customers description it sounds like there are no parts breaking down at all just that the heater needs to be re lite. It is the same heater that always needs to be re-lit. Both vents terminate outside. The only difference that I can see is that directly above the vent for the "bad"  water heater, is a 4" PVC pipe that I am guessing is supposed to bring combustion air inside. The PVC pipe is capped inside the house and hence has no function at all. Is it possible that that capped PVC pipe could be contributing to the water heater flame blowing out? Thanks


    STEAM DOCTOR Member Posts: 1,368

    Neglected to mention that the vent terminates about 12" inches above the ground. I am assuming that this is a big no-no. The home is in NYC(Queens) which regularly gets more then 20" of snow. Can I extend the vent pipe up and put two 90's on top to have the vent point down? Also is the a minimum distance that the two vents have to be from each other and the combustion air pipe? Thanks.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    edited June 2011
    What model number of water heater?

    If it has an inducer motor on it, I'd THINK it should have a supervised pilot on it. Ignition module and all.

    If it has a standing pilot on it and is only 80% efficient, it is not supposed to be vented in PVC. Their flue gases are too hot for plastic without having a lot of dilution air as would be introduced from an inducer..

    I'd recommend you find the I&O manual and follow that to the T. Now that you've touched it, you OWN it... Even if all you did was relight a pilot light.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
    STEAM DOCTOR Member Posts: 1,368

    The heater has a standing pilot. It is not vented in PVC. The PVC is supposed to be for combustion air. I wasn't able to lite it because the gas control is broken. I don't have the model #. It is a 20 year old AO Smith.
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