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  1. #1
    I've looked around the archives, and have a pretty good idea of the basics of my problem, but had questions about specific questions to ask our contractor and what my expectations should be.

    My wife and I live in the metro DC area, and our house is a one-story ranch house. We replaced the central A/C unit and furnace in Sept. 04. The old furnace was fine (no condensation problems and heated well), but the contractor convinced us it would be cost-effective to replace it at the same time as the A/C since it was almost 20 years old.

    We now have a new 80% efficient furnace and have been having condensation problems ever since we turned on the heat in the late fall. The condensation is a light, oily substance the color of light machine oil or 3-in-1 oil and is driping back down the flue and onto the basement floor. The condensation is so bad that it also discolored the drywall in a closet that is next to the chimney.

    The contractor came back once, looked up the chimney and said, "Yep. Condensation." He told me to go into the attic and wrap the transite vent with insulation, and I wrapped fireproof insulation around the transite vent from the attic floor on up. No change. The condensation is just as bad.

    Before I call this guy back, I want to make sure I ask the right questions and have him run the right tests so he doesn't just leave after 2 minutes like last time.

    Should this contractor have replaced or recommend replacing the transite vent originally? (Unlike some jurisdictions, I don't think it's required under our county code.)

    What tests should I ask this guy to check when he comes back? What are possible fixes he might (or should) recommend? Also, who should pay for this fix?

    After coughing up almost 6 grand I don't think the fix should come out of my pocket because the problem didn't even exist until he did the work.

  2. #2
    Join Date
    Feb 2004
    6 grand for a new furnace and central A/C, me thinks you got what you paid for. Have them check the stack temp, I don't like to see it under 300*F for a noncondensing appliance, 275*F minimum. Is the furnace oil or gas? Did they inspect the chimney before installing? Is this an outside chimney? Is it lined? Around here any new install requires that the chimney be lined if it's not.

  3. #3
    The furnace is gas, and I don't believe they inspected the chimney before giving us the estimate for the new system. I could be wrong though. To the best of my knowledge, the chimney is not lined. Just a white, transite pipe going up through the center of the house. (Our furnace is in the center of the basement, and the vent goes straight up from there.)

    When you say we got what we paid for, were you referring to the quality of the system or the installation? According to the research I did before we bought, Trane seemed to be a pretty good system. We got 4 estimates and they were all pretty close to one another. Am I missing something obvious?

  4. #4
    Join Date
    Feb 2004
    are you sure this is an 80% and not a 90%.

    is the venting the proper size? would be one question to find out.

    it would help to know more info. such as model numbers, then perhaps an authorized trane dealer will be able to help you.

    by "transite" do you mean pvc?

  5. #5
    Join Date
    Jan 2005

    Hmm Condesation

    When you say chimney do you
    mean like brick? Or do
    you have a big round pipe?
    If it is a pipe how big
    around is it? Also can you
    measure how tall it is from
    the basement to the top?
    Would also need to know
    the btu's of the 80%
    furnace.Is there a gas hot
    water tank(btu"s also) that
    goes into it also.Last but
    not least is there anyway you
    can post some pictures of this?
    It would help use help you.
    LOok forward to helping if
    we can.

  6. #6
    Gasman why does your type come out in such a narrow border?it is a very slow read. Is it just me or is there something wrong?

  7. #7
    Thanks for the great follow-up questions. I'll answer those I can now, and take some pictures and get the exact model number over the weekend.

    Yes, I'm sure it's an 80% rather than 90% gas furnace.

    Sorry if I'm using the wrong terminology. By "chimney" I mean the pipe into which the (appprox.) 5 inch diameter exhaust from the furnace vents. There is no brick chimney, just the white pipe going up through the center of the house and into the attic.

    "Transite" is what the Trane dealer who installed the system called the pipe. As I understand it, transite is essentially asbestos encased in cement. Definitely not PVC. Our house was built in 1962 before they stopped using asbestos.

    I have no idea if the vent is the proper size. Our house has about 1,000 square feet of living space plus an equal amount of space in the basement. Although the basement is heated by the same furnace, the basement is not insulated or finished. Just concrete block walls and linoleum tile over concrete floor.

    I'll post photos, get the measurements, and provide the Model # after the weekend.


  8. #8
    Join Date
    Jan 2004
    What size is the furnace, what is the heigth of the chimney, how long is the flue pipe to the chimney, is it single wall, or b pipe.

    did the installer do a temp rise check across the heat exchanger.

    Your most likely going to have to line the transtite, its around here also, and that is a common problem when a new furnace is hooked to them, we either run b pipe inside the transtite or run a liner and insulate it to keep it from condensating.

    Ps: transtite was also used as sewer pipe.
    Contractor locator map


    How many times must one fix something before it is fixed?

  9. #9
    Join Date
    Feb 2004
    can you go w/ a chimney friendly kit with transite?

  10. #10
    Join Date
    Jan 2004
    You mean a dilution kit?

    As far as I know you will still have the same problem.

    Contractor locator map


    How many times must one fix something before it is fixed?

  11. #11
    Join Date
    Sep 2001
    angola indiana

    transite chimney

    I have ran into this problem before. Replace the transite chimney with class B vent.

  12. #12
    Join Date
    Mar 2002
    Northeastern Illinois
    I agree with hal. But if the transite chimney is still good just have a flexible liner put in. I had the same thing happen and the transite turned to mush. We replaced it with B vent. No more problems.
    If it ain't broke don't fix it!!

  13. #13
    Thank you to everyone who's responded. I took some measurements and photos over the weekend, and I'll try to answer the questions from Gasman, Beenthere, and others.

    I posted photos of the system and condensation problems at

    The furnace is a Trane XR 80, model #TUD080C936. I wasn't able to tell how many BTUs it produces or is rated for.

    The furnace vents via a single-wall, 4 inch diameter pipe into the chimney vent. The length of the vent pipe from the furnace to the vertical chimney that goes through the house is approx. 5 ft.

    The chimney vent runs behind drywall through the living area, so I can't see it all and don't know how much of it is transite or single wall galvanized.

    If the chimney vent is transite all the way up, it is approx. 15 feet long. (8 ft. in the living area + 5 ft. attic floor to roof + 2 ft. above roof.)

    The transite vent has an outside diameter of just under 7 inches in the attic.

    A gas water heater also vents into the same pipe (photos on website), but I don't know the BTU rating for the water heater.

    I don't know if the installer did a temp rise check across the heat exchanger.

    From what many of you have posted and what I've read on the archives, it seems likely that we will have to install B-vent to fix the condensation problems.

    If we do have to install the B-vent, is this something the licensed and authorized Trane dealer who did the work should have known up front and told us about?

    And who should pay to fix the condensation, us or the contractor? It's irritating because we didn't HAVE a condensation problem until they installed the new system. (The old system worked fine, but he talked us into replacing it at the same time as the dead A/C unit.)


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