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  1. #1
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    May 2018
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    Furnace Condensate Acidity?

    My high efficiency furnace (installed 2 seasons ago) is in my basement. The furnace and AC condensate lines feed into a floor drain that flows into an ejector pit that goes to city sewer. The home was built in 2001.

    The ejector pit only gets water from the HVAC and in winter time only the furnace and humidifier.

    Will the acidity of the condensate from the furnace damage my pipes or sump pump that I have in the ejector pit? I have read conflicting information on this.

    If so, any easy way to neutralize this? Poor gallon of water in floor drain? Maybe add teaspoon of baking soda once a month??

    Thanks in advance.

  2. #2
    Join Date
    Jun 2012
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    Northern NV
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    It is acidic, but not too much. You can taste a drop on your finger and get a feel for it. I've done this as I was curious myself. I have never installed a condensate neutralizer unless the jurisdiction and inspector require it.

    The water from your humidifier will likely be very alkaline so it may not be a bad thing to have a bit of acidity....

    I am sure you will get a plethora of opinions on this.
    “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.”
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  3. #3
    Join Date
    May 2000
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    Indianapolis, IN, USA
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    It's less acidic than Cola

  4. #4
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    Mar 2018
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    Chico, Ca #StateofJefferson
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    I've seen rats drink off of it and they lived!

  5. #5
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    May 2018
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    Thread Starter
    I am more concerned with the drain pipe. Would cast iron be used in a floor drain of a house built in 2000? Everything else is PVC but the floor drain looks like cast iron (but I’m not sure).

    When I look in the floor drain there is some reddish rust in both the drain and the sump pit and some on the sump pump itself. It works fine and I will probably replace the pump in the next year or so anyway but don’t want my floor drain to corrode and cause damage since it is under the concrete floor.

    So should I try and put a neutralizing media filter on it? Or am I worried about nothing??

  6. #6
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    Sep 2002
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    Why guess?

    https://www.amazon.com/Paper-Litmus-...8963785&sr=8-3


    Quote Originally Posted by DVA79 View Post
    My high efficiency furnace (installed 2 seasons ago) is in my basement. The furnace and AC condensate lines feed into a floor drain that flows into an ejector pit that goes to city sewer. The home was built in 2001.

    The ejector pit only gets water from the HVAC and in winter time only the furnace and humidifier.

    Will the acidity of the condensate from the furnace damage my pipes or sump pump that I have in the ejector pit? I have read conflicting information on this.

    If so, any easy way to neutralize this? Poor gallon of water in floor drain? Maybe add teaspoon of baking soda once a month??

    Thanks in advance.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  7. #7
    Join Date
    Jan 2004
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    PA
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    Quote Originally Posted by Makeitcold View Post
    I've seen rats drink off of it and they lived!

    But since the rats were in California, they got cancer from it.
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  8. #8
    Join Date
    May 2018
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    Thread Starter
    I ordered a PH meter today and will test when it comes in.

    I did see a lot of iron bacteria/red slime in the pit when I removed the cover. Is this evidence of acidic water or just from never being cleaned?

  9. #9
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    Mar 2018
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    Chico, Ca #StateofJefferson
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    Slime is something breeding, find it in commercial ice machines all the times. Basement installs arent very common around here but I've seen a decent amount of condensing furnaces draining into a basement sump pump pit, many for 10-20 years with no ill effect

  10. #10
    Join Date
    Aug 2009
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    Beatrice, NE
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    I have been told that it has the same acidity as orange juice.

    Years ago One of the first brands of 90% furnaces we installed had a canister on the side that the condensate ran through. It was filled with something like antacid tablets for a horse. Since that time I have never seen a manufacturer make any comment on the issue except it should not be a problem in most drain systems. Also I would think on a house built in the 2000's ever part of the drain system would be PVC, have not seen a cast floor drain in a new house, ever. When I first got into the trade copper was used for all the drain lines, don't remember what was used for a floor drain.

  11. #11
    Join Date
    May 2018
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    Thread Starter
    Thanks. Once I confirm PH value I may look at rigging up something like a canister filled with limestone to neutralize the condensate before going to the floor drain. M

    As far as cast iron, I really can’t tell. The floor drain appears to be some type of iron and does not look like the white PVC that is everywhere else in the house.

    Do newer home use something other than PVC for basement floor drains?

    As for the red slime, I may just shop vac it all out and then throw in some oxyclean into the drain periodically.

  12. #12
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    Mar 2018
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    Chico, Ca #StateofJefferson
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    Let us know what you find

  13. #13
    Join Date
    May 2018
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    Thread Starter
    So I tested the water twice:

    First in the drain water itself: PH was about 5.5.

    Second, I tested the water coming directly out of the furnace condensate line. That was definite more acidic at 3.37.

    Here is a picture: https://imgur.com/a/RduWrNT

    So, should I put a neutralizer on this?

    Has anyone actually seems furnace condensate damage a pipes and pumps?

    Not sure if you can tell, but is this floor drain cast iron? Will the condensate erode it?

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