Connect Direct Vent WaterHeater to chimney flue?

Discussion in 'HVAC Heating & Cooling' started by fineline, Feb 28, 2008.

  1. fineline

    fineline Design/Build

    Messages:
    25
    Location:
    New Jersey
    Can you connect a direct vent hot water heater to a standard masonry chimney flue? Reason I ask -- my water heater has pretty much died so I need to purchase a new one. I also know that my chimney flue is soon in need of a re-lining -- so I was going to purchase a direct vent water heater since its cheaper then re-lining the chimney. I'd like to hook it up to the chimney flue temporarily because I'm in the middle of a kitchen remodel and don't have time to run the vent the way that I would like too, and I'm even considering moving the water heater location altogether once the kitcen is done. Wouldn't take me more then a couple hours to replace the old water heater if I can just hook it back up to the chimney flue and get by like that for a few weeks.

    Is this a bad move?

    Thanks,
    SD
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Go to a manufacturer website....i.e. rheem.com and download the installation instructions for a direct vent. In general, I think your answer is NO, because direct vents also take combustion air in through a coaxial vent.
  3. BigLou

    BigLou New Member

    Messages:
    138
    all of the direct vent literature I have seen say Do not do that, It may work for a very short period of time but I would still take the time do it right
    Lou
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,798
    Location:
    Cave Creek, Arizona
    heater

    is it a direct vent heater with combustion air from the room, or a sealed combustion heater with the coaxial vent/intake, (or separate intake and exhaust)? Are there any other devices connected to the chimney. If the exhaust vent is individual and this is the only thing connected to the chimney you should be okay for a short time.
  5. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
  6. fineline

    fineline Design/Build

    Messages:
    25
    Location:
    New Jersey
    thanks for the replies -- I was looking at the Rheem Fury Direct Vent, and the manual does say that if the heater is in an unconfined space - mine is - then infiltration air is adequate for proper combustion and ventilation - and trust me when I say there is no shortage of infiltration air in my house.

    the chimney flue is shared by the boiler so that is a strike against me. At the prices I have received for the chimney re-line, I would be better off buying a draft vent heater to get me by for now, then buying the new direct vent when I'm ready to move the location - pretty sad huh.
  7. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    This is from the manual for the Fury Direct vent:
    "
    Combustion and Ventilation Air​
    Proper operation of the water heater
    requires air for combustion and
    ventilation. Provisions for combustion
    and ventilation air must comply with
    referenced codes and standards.
    NOTICE: If the water heater is
    installed in an unconfined space within a
    building of conventional frame, masonry
    or metal construction, infiltration
    air is normally adequate for proper
    combustion and ventilation. If the water
    heater is installed in a confined space,
    provisions for ventilation air must be
    made.
    All air for combustion and all products of
    combustion are routed through the ducting
    provided, directly from and to the outside
    of the building"


    You referenced the paragraph which I have highlighted in blue. Frankly, I think this is a mistake in the Rheem manual. It may have been cut-and-pasted from the manual for a conventional WH. The paragraph which I highlighted in red is I think the correct statement. I looked at the whole manual, and I did not see where it offered ANY option for venting except directly to the outside through the coaxial vent. I could be wrong, but I would certainly call Rheem tech support before trying to gravity vent this model.
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