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  1. #14
    Join Date
    Nov 2018
    Location
    Pasco FL
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    10
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    Quote Originally Posted by 4inchCrescent View Post
    One of my guys and I were replacing a direct vent wall furnace in a little guest cottage with a tenant living in it. I went to take a leak and saw this fine installation right next to the toilet.

    Attachment 803731Attachment 803732Attachment 803733
    Thats an accident waiting to happen

  2. #15
    Join Date
    Dec 2004
    Location
    Caledonia WI
    Posts
    1,875
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    It already happened...


    Quote Originally Posted by tatortott View Post
    Thats an accident waiting to happen
    It's not what you're capable of doing that defines you, it's what you do on a daily basis.

  3. #16
    Join Date
    Sep 2005
    Location
    Atlanta GA area
    Posts
    38,943
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    There 'is' barely enough room for a skinny tall gas water heater in that corner... stuff job, and definitely not code.

    Question for you tankless guys:

    I saw a double tankless (paired, with the linking cable) installed in a clean, large crawl a while back (just guessing... the crawl was probably in excess of 2000 sq/ft floor, and I could walk in it)...
    Flue pipes were done quite well... however the installer did not do combustion air pipes. The combustion side had about 5 ft of pipe each. Note there was more than adequate combustion air in the crawl...

    My question: specifically (asking for technical reasons) Why do the tankless folk want combustion air piped from outside???
    Just curious...

    THX

    GA
    GA-HVAC-Tech

    Your comfort, Your way, Everyday!

  4. #17
    Join Date
    Sep 2002
    Posts
    23,402
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    The intake and outlet venting for a tankless heater must come from an area of always-the-same pressure. The reason is that, if they don't, any low pressure inside the space can draw in cold outside air, through the tankless, while the tankless is off - and freeze the heat exchanger.

    So long as both intake and exhaust are in a place of equal pressure (relative to each other) no off-cycle air flow can be induced through the tankless.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  5. Likes Core_d liked this post
  6. #18
    Join Date
    Apr 2003
    Location
    Maple Grove, MN
    Posts
    2,852
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    Quote Originally Posted by Poodle Head Mikey View Post
    The intake and outlet venting for a tankless heater must come from an area of always-the-same pressure. The reason is that, if they don't, any low pressure inside the space can draw in cold outside air, through the tankless, while the tankless is off - and freeze the heat exchanger.

    So long as both intake and exhaust are in a place of equal pressure (relative to each other) no off-cycle air flow can be induced through the tankless.
    That's a very good point and something I would have never thought of. Thanks for pointing this out.

  7. #19
    Join Date
    Jul 2007
    Location
    Beautiful, Philadelphia, the City of Brotherly Love!
    Posts
    1,248
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    Piss on that.
    “You don't get paid for the hour. You get paid for the value you bring to the hour.” Jim Rohn

  8. #20
    Join Date
    Sep 2005
    Location
    Atlanta GA area
    Posts
    38,943
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    Quote Originally Posted by Poodle Head Mikey View Post
    The intake and outlet venting for a tankless heater must come from an area of always-the-same pressure. The reason is that, if they don't, any low pressure inside the space can draw in cold outside air, through the tankless, while the tankless is off - and freeze the heat exchanger.

    So long as both intake and exhaust are in a place of equal pressure (relative to each other) no off-cycle air flow can be induced through the tankless.
    Quote Originally Posted by ammoniadog View Post
    That's a very good point and something I would have never thought of. Thanks for pointing this out.
    THX PHM... I would never have thought of that either... however it makes good sense!
    GA-HVAC-Tech

    Your comfort, Your way, Everyday!

  9. #21
    Join Date
    Jan 2019
    Location
    Wichita Kansas
    Posts
    23
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    Uhm ? Ifgc chapter 3 not a quote . Dont take combustion air from a bathroom . Is this a confined space as far as combustion is concerned.lol

  10. #22
    Join Date
    Nov 2014
    Posts
    2
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    I mean yeah you notice it, but only because you know its there.

  11. #23
    Join Date
    Jul 2010
    Location
    napping on the couch
    Posts
    10,894
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    The poop fumes gives the combustion an extra boost.

    Like nitrous in a car.

  12. #24
    Join Date
    Oct 2014
    Posts
    128
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    Quote Originally Posted by kdean1 View Post
    I am especially fond of the positive pressure PVC exhaust connected to the single wall vent with foil tape. Someone was probably very proud of their ingenuity.
    Painted the metal 90..now that is craftsmanship


    Sent from my iPhone using Tapatalk

  13. #25
    Join Date
    Jun 2012
    Location
    Northern NV
    Posts
    1,478
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    Intake and exhaust in same pressure zone to minimize nuisance trips of the pressure switches as well. (wind)

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