Thru wall venting concern

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Grinbau, May 5, 2006.

  1. Grinbau

    Grinbau New Member

    Messages:
    2
    Location:
    Media, S.E. PA
    In my current house both furnace and water heater are new and high efficiency thru-wall models. However there is a considerable problem with these - fumes coming back into the building. this is especially true for the water heater, which is on all the year including when windows are open. But in any case the fumes seem to find their way into the basement thru cracks somehow.
    I want to find out how far I could really run the vent pipe away from its exit point at the top of the basement wall. Since it's power vented it's quite possible it would work fine with more pipe and more bends than the manufacturer says (I believe that is 25 or 30 feet).
    In my new house I am going to have the boiler vent out thru a chimney flue that's for sure. In the meantime any ideas, observations?
  2. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    If you have the type that doesn't bring in combustion air that is the problem. When the furnace or WH turn on that causes negative air pressure and it will pull in through the easyest pathway which must be near the termination points, perhaps the holes cut for the exaust pipeing.

    See if there is a place that you can add another peice of combustion air flue pipe, that is not near the furnace and WH termination and run it to or as close as possible to the WH and furnace. 6" is normaly used.

    Also look near the WH and furnace termination points, inside and outside the house, and caulk all gaps or places that air could infiltrate.
  3. finnegan

    finnegan New Member

    Messages:
    250
    Location:
    CT
    I had a boiler replaced about a year ago and a guy tried to sell me on a direct vent model that did not have sealed combustion. I have no idea why they make boilers that way.
  4. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    The reason they originaly were made that way was because houses were so full of "holes", and fuel so cheap it didn't matter. Why they still are that way is a mystery to me.
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