Direct Venting vs Natural Venting
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  1. #1
    Join Date
    Mar 2005
    Posts
    12
    Hi all,
    I am considering a HI-Efficiency gas boiler replacement for my 50 year old cast iron oil boiler. They only drawback I see is that the direct vent has to go to side of the house (un-paved shared laneway) and it will not look very nice. Two black PVC pipes sticking out from the foundation and running about 3 feet high. The drawbacks I see are
    1. Unsightly
    2. Moisture problems with the brick veneer
    3. Can be easily plugged by animals or by mischief
    4. Coring the limestone foundation may cause cracks.

    Is there any reason why Hi-Efficiency boilers can not use natural vent (i.e. Chimney) with an appropriate liner? Is the a problem with condensation in the flue gas (100 F)

    If a still want to use my chimney with an appropriate liner what other hi-efficiency gas boilers >= 88 % (AFUE) are available?

    I want to consider all my options because I see this as a long term investment.

    thanks in advance
    John K


  2. #2
    Join Date
    Aug 2004
    Location
    west hartford, ct
    Posts
    74
    Why not use the chimney as a chase. The pvc pipe can be installed in your existing chimney. This will alleviate all those concerns you posted.

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,597
    Originally posted by smarks
    Why not use the chimney as a chase. The pvc pipe can be installed in your existing chimney. This will alleviate all those concerns you posted.
    Good suggestion.

    Also, local code may require your vent to be 7' above that shared lane.(NFGC does)
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  4. #4
    Join Date
    Feb 2003
    Posts
    1,996
    Som people do get some ice dams forming on the roof as cool exhuast condenses and freezes as soon as it hits the cold air. May want to insulate the PVC going up the chimney.

  5. #5
    Join Date
    Apr 2005
    Location
    Farmingdale NJ
    Posts
    36
    Direcr Vent High Efficiency up to 93% but cost about a third more as much as conventional which with induced draft is about 83% Takes a number of years to make up the cost difference.but if you can afford it go for the best why not You'll have it for twenty years. Meanwhile you'll go through 3 or 4 high priced cars in that time with lots more maintenance

  6. #6
    Join Date
    Apr 2004
    Location
    Niantic, Illinois
    Posts
    545
    Originally posted by smarks
    Why not use the chimney as a chase. The pvc pipe can be installed in your existing chimney. This will alleviate all those concerns you posted.
    Just be sure nothing else is venting into the chimney. I would hate to see the water heater flue melt the pvc for the boiler.

  7. #7
    Join Date
    Aug 2004
    Location
    west hartford, ct
    Posts
    74
    If you are going to install a high efficiancy boiler it would be foolish to keep the gas water heater. Buy an indirect heater to match the boiler. You will save on fuel and not have the problem previously posted. Fuel prices are not coming down any time soon if ever.

  8. #8
    Join Date
    Nov 2001
    Location
    Moose Jaw, Saskatchewan, Canada Occupation:Interprovincial Plumber, Commercial Gasfitter Interests:
    Posts
    2,412
    Originally posted by cbmechanical
    Direcr Vent High Efficiency up to 93% but cost about a third more as much as conventional which with induced draft is about 83%

    Just out of curiosity, up here, when I add a control like a tekmar to a standard boiler, there is not much of a price difference. Is it the same down there?
    I love my job, but paydays Thursday

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