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  1. #1

    Flue Pipe Safety Concerns

    While in the crawlspace under my house today, I saw a few things that caused some concern. 1) The seams on the flue pipe are showing signs of corrosion 2) Water was dripping from the transite pipe, and 3) The transite pipe is being held in place by a wood bracket and is deteriorating because of the drip. It rained fairly hard the past couple of days but had not been raining for about 8 hours when I went under the house. I looked in the attic and did not see any sign of water infiltration from the roof end. I am going to have a few HVAC specialists give me their opinion/estimate, but I was hoping to get an unbiased opinion here as well.

    I was told by my home inspector when I bought the house 5 years ago that the angle of the flue pipe from the furnace to the transite pipe was too shallow. Whoever did the installation used the original c. 1942 transite pipe from an old wall furnace rather than run a new pipe because it was cheaper and easier. I have a carbon monoxide alarm inside the house and thankfully it has not sounded.

    I'm guessing that the HVAC company will recommend running a new vent pipe to the side wall of the house and up the exterior and through the eaves. Removing/replacing the transit pipe would be costly and would not correct the vent pipe angle issue. Any idea how much this would cost? Please see pictures. And, yes, the rat issue has been remediated but not before they damaged the duct insulation. Many thanks for your thoughts and suggestions.
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  2. #2
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    Mmmmm, a long run of single wall pipe in an unconditioned space, and a nearly flat run to boot...
    If more government is the answer, then it's a really stupid question.

  3. #3
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    6,191

    Cool

    Ladysue, you have several issues here. First of all, it would help if you could furnish the make and model of the furnace and BTU input rating. Second would be the lateral offset to the Transite and third would be the vent rise from the appliance collar to the Transite and fourth would be the total vent height.

    Transite was an expediency to conserve aluminum during WWII. It is not suitable for the class of service and should be removed regardless of condition. Transite does require a 1" clearance to combustibles so it cannot sit on wood or touch it. Transite runs so cold it causes flue gas condensation. I get calls all the time for "leaks" which turn out to be condensation from Transite.

    The vent connectors must be type B-vent because you are in an unconditioned space. Single walled pipe is not allowed in unconditioned areas, which is one reason for the rotting pipe you see. Vent connector must have a 1/4" per foor rise. The connector should be properly secured at each joint with screws and supported at offsets and as needed, usually every 4ft. Single walled pipe carries a 6" clearance to combustibles while B-vent requires 1".

    Before you remove the Transite and run B-vent up the side of the house, consider switching to a CAT. IV condensing furnace and power vent it legally out the side of the house.

    Sorry but Site Rules prohibit discussing pricing.

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,074
    I've run B vent up the transite pipe.
    Contractor locator map

    How-to-apply-for-Professional

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

  5. #5
    Join Date
    Mar 2005
    Location
    Suppy NC
    Posts
    4,513
    i wold also have the transit check to make sure it isn't asbestos since it is old enough to be
    if so best to just abandon it and run a new chimney or switch to a new direct vent furnace

  6. #6
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,535
    Beenthere has simpliest idea. If the diameter of the old pipe is adequate, just have a contractor run B flue up thru the old transite pipe and back to the furnace. I'll bet you've got an 80% furnace in this crawlspace, which would cause flue to degrade from moisture. Replacing furnace with dual piped +90% furnace would also work, but be more expensive. Putting a dehumidifier in this crawlspace may not be a bad idea either as looks like it's pretty wet under there. Is the dirt floor covered with 4 mil. plastic?

    Transite is made from cement and asbestos last I knew.

  7. #7
    Thank you all for your replies. The furnace is an ~80% efficiency Rheem model #RGPH05NAUER, only 50,000 BTUs to heat a 1,000 sf house. The serial nbr indicates it was made in 1995, so it's 17 years old. An HVAC contractor indicated to me that the reason a single-walled flu pipe was used was because the O.D. of a B vent pipe is too large to fit inside the transite pipe. The single wall pipe is roughly 15' long and has many articulations as you can see. He recommended replacing the pipe with the same material to "buy me another 5 years" or until this furnance craps out. A colleague at work recommended replacing the pipe AND insulating it to keep it hot enough so the vapors will not condense through the shallow rise to the vertical pipe. Wahoo, yes the soil is covered with black plastic but it had rained quite a bit recently so it was pretty soggy underneath. I'll consider using a dehumidfier during the winter rainy months. Thanks again for your comments.

  8. #8
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,535
    Make sure you keep a working Smoke, and Carbon Monoxide detector in your home just in case this furnace does not draft, or causes a problem. Anytime we have a customer with a gas, oil, or wood furnace we recommend they have a Carbon Monoxide detector along with a smoke detector in home.

  9. #9
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    Quote Originally Posted by wahoo View Post
    Anytime we have a customer with a gas, oil, or wood furnace we recommend they have a Carbon Monoxide detector along with a smoke detector in home.
    Fuel burning furnaces don't even make the top 10 list of causes of carbon monoxide poisoning.
    The things responsible for the vast majority of carbon monoxide poisonings are equally as likely occur in a home with no combustion appliances in it as in a home with combustion appliances.

    Everybody needs a CO detector in their home.
    If more government is the answer, then it's a really stupid question.

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