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  1. #1
    Join Date
    Dec 2019
    Posts
    5
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    New Furnace installed using existing flu and now condensate problem

    I had a new furnace installed last year, now we are getting condensate dripping and also some rust spots on top of the furnace and inside as well. I wanted to nip this issue in the bud so I called the installers. They said there was nothing they could do - that all 80% efficiency furnaces have this issue. I replied that my previous 25 year old 80% furnace didn't have this issue - what's changed?

    We gave a flat roof.
    5 foot section of 4" B vent goes through ceiling/roof.
    There is a galvanized single wall elbow, 2 foot section at a slight angle and another elbow into the top of the furnace.
    66,000 BTU in
    53,000 BTY out

    I have read that the burner can be adjusted to prevent this. They did no testing at all, other than to see if it ran.

  2. #2
    Join Date
    Jan 2004
    Location
    PA
    Posts
    78,404
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    Possible that the blower is moving too much air. Or its not fired at it full 66,000 BTU input.

    What temp do you maintain it the house.
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    How many times must one fix something before it is fixed?

  3. #3
    Join Date
    Dec 2019
    Posts
    5
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    Thread Starter
    At night we keep it at 68. During the day 70-72
    One more thing. There is an AprilAir humidifier attached to the new furnace. We keep it set between around 25-35 percent humidity dependent on outside temperature.

  4. #4
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    7,282
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    Need to run combustion analysis. Also consider a post purge cycle of about 4 minutes if not already.

  5. #5
    Join Date
    Dec 2019
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    5
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    Thread Starter
    Thanks. Will call tomorrow for that. The installer recommended I run b vent all the way to the furnace. Said that might help. What do you think? 4 seems to be correct sizing. Could the stack be too short?

  6. #6
    Join Date
    Sep 2007
    Location
    State College, PA
    Posts
    2,970
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    Have you called the manufacturer of the furnace? They should be able to help you out.
    Can someone please explain to me -
    Why is there never enough time to do it right the first time, but plenty of time to do it twice?


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  7. #7
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    7,251
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    Quote Originally Posted by JohnnyJack View Post
    Thanks. Will call tomorrow for that. The installer recommended I run b vent all the way to the furnace. Said that might help. What do you think? 4” seems to be correct sizing. Could the stack be too short?
    When you say "I" does he mean you, or does he mean he?
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  8. #8
    Join Date
    Jan 2012
    Location
    Broomall, PA
    Posts
    2,950
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    What was the btu size & make and model of the previous furnace?
    If I do a job in 30 minutes it's because I spent 30 years learning how to do that in 30 minutes. You owe me for the years, not the minutes.

  9. #9
    Join Date
    Oct 2011
    Location
    Gladstone, Oregon (Portland)
    Posts
    2,132
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    Is the furnace a Goodman?

  10. #10
    Join Date
    Dec 2019
    Posts
    5
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    Thread Starter
    Quote Originally Posted by STEVEusaPA View Post
    What was the btu size & make and model of the previous furnace?
    It was a Trane
    Model:TUSO60A936A1
    60,000 BTU Input

    09/89 (whoops it was more than twenty five years old)

  11. #11
    Join Date
    Dec 2019
    Posts
    5
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    Thread Starter
    The new furnace is a Lennox bought through Costco. Model ML180

  12. #12
    Join Date
    Jan 2004
    Location
    PA
    Posts
    78,404
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    Quote Originally Posted by joemach View Post
    Have you called the manufacturer of the furnace? They should be able to help you out.
    The manufacturer won't talk to the home owner. About technical aspects.
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    How many times must one fix something before it is fixed?

  13. #13
    Join Date
    Jun 2012
    Location
    Northern NV
    Posts
    2,007
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    Should be B vent all the way. No single wall.
    A dying culture invariably exhibits personal rudeness. Bad manners. Lack of consideration for others in minor matters. A loss of politeness, of gentle manners, is more significant than is a riot.
    ― Robert A. Heinlein

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