Venting a gas water heater

Discussion in 'HVAC Heating & Cooling' started by zenn68, Aug 1, 2008.

  1. zenn68

    zenn68 New Member

    Messages:
    12
    hope this is the right section for this question.
    I am changing out an electric water heater for 2 propane fired models.
    1 for the domestic hot water usage, and a 2nd to run the radiant heat system I am putting in.
    The location of the tanks does not allow a vent pipe to go straight up to the roof, right now I'm looking at running a vent pipe about 11feet horizontally to an exterior wall then up the side of the house to roof level.
    Does this sound right?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,313
    Location:
    New England
    To maintain a decent draft, there are limits on how far you can go...it depends on the manufacturer. I'd prefer maybe a powervent in this situation that vented out the sidewall. ALso, keep in mind, unless your BTU requirements are fairly small, a WH may not be able to supply your needs. The type of heat loops (radiators, in-floor, panels, etc) each require different temps. Some require higher than a typical WH can provide. The average WH probably won't have the reliability of a boiler, either. Today's modulating HE boilers are in the mid-90% efficiency range and can easily provide all the DHW you want more efficiently than a WH.
  3. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,395
    Location:
    Yakima WA
    With all due respect, I think you should get a professional to handle this installation. Not only does the venting have to be done right, the question on having the right kind of heater for the radiant heating needs to be addressed. You can get some pretty sound advice here, but it really needs to have a professional on site.
  4. zenn68

    zenn68 New Member

    Messages:
    12
    thanks for the infi,

    should point out that the 2nd water heater is a radiant heat specific type.
  5. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    The installation manual for your water heater will have specific instructions on allowed venting. For example, it will be required to run a certain minimum distance vertical before turning horizontal. There will be limits on # of elbows, and there will be a minimum ratio of vertical pipe length to horizontal pipe length.

    Most manufacturers have the manuals available on line to look at.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,230
    Location:
    Cave Creek, Arizona
    vent

    Unless the outside vertical pipe is insulated, heat loss will prevent a normal draft from forming and you WILL get carbon monoxide fumes in the building.
  7. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    Zenn, Really for the safety of you and your family please consider hiring a pro to properly select the water heater and installation methods used.

    Gary Swart's concerns are very real! Installing Gas Appliances is not a hobby!
    Its hard to say what the worst case scenario is...
    An empty building lot with a pile of toothpicks in it...
    Or,
    A whole family not waking up in the morning...
    Both are about equally bad!
    But, I'll say the toothpicks is probably the better one. It may happen when you are not home and if it does happen when you are home then there exists a possiblity that the blast injuries and burns will not be fatal....
    Not waking up in the morning almost always is fatal.:eek:
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