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    Direct Vent 80% boiler (8 Posts)

  • Ron123 Ron123 @ 1:30 PM
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    Direct Vent 80% boiler

    Is it possible to vent an 80% efficient boiler directly outside without going through a chimney?
    About 6-7 years ago I had a brand new boiler installed to replace the nearly 100 year old original boiler.  The contractor told me they could use the existing chimney for the boiler and the hot water tank.  All appeared to be fine for the first 2-3 years, but in about year 4 the chimney in the attic started to appear to deteriorate from the inside.  The chimney is partially inside and partially outside of the house, which is 3 stories tall.  The deterioration is in the form of the paint and plaster covering the brick is damp and pealing.  When I bough the house the chimney was fine and has progressively gotten worse since I noticed in 3 years ago.
    I would like to know if there is anyway I could pull the vent pipe out of my chimney and run it directly outside.  The boiler sits near an outside wall so the length of pipe it would need to travel to get outside would be 8-10 feet.
    Thanks for any help.
  • Chip Chip @ 4:02 PM
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    tjerlund

    Tjerlund makes a sidewall venter, that are designed to be installed on 80% boilers. I can not say it would work in your instance. You need to find a qualified contractor in your area to investigate. Did previous installer put a liner in your chimney when it was installed? Chip
  • Chip Chip @ 4:02 PM
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    tjerlund

    Tjerlund makes a sidewall venter, that are designed to be installed on 80% boilers. I can not say it would work in your instance. You need to find a qualified contractor in your area to investigate. Did previous installer put a liner in your chimney when it was installed? Chip
  • Ron123 Ron123 @ 12:44 PM
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    Liner

    No, they said a liner would not be required.  When the problem first appeared I called the installer back and he said a liner couldn't be installed because the flu was too small (only 8"), and that shifting has probably happen with the clay flu pipes and the age of the house.
    Last summer I got up on the roof and looked down the flu as best I could and the pipes all seem pretty lined up without too much shifting.  The chimney is about 6 feet wide at the base (the fireplace shares the chimney but has it's own flu) and the chimney is about 4 feet wide at the top.  The boiler flu pipe enters on once edge of that 6 feet and must have  bend in it at some point since the chimney goes down to 4 feet wide.
    I see on that Tjernland site that they have chimney fans.  Would that work?
  • McMaster McMaster @ 12:15 AM
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    Condensing

    Have you seen moisture at the bottom of your chimney?

    You're most likely getting condensing in the chimney as the flu gases rise. The top of the chimney is probably pretty cool and some condensate forms and runs down the inside of the chimney. The consdensate is somewhat acidic and it eventually can lead to all kinds of problems, including deteriorating mortor.
  • Ron123 Ron123 @ 8:11 AM
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    Chimney Fan

    Will a chimney fan draw enough of the exhaust gases to get them out before they condense?  The chimney is about 40' tall.
  • STEVEusaPA STEVEusaPA @ 4:32 PM
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    I wouldnt

    What fuels are the boiler and the hot water heater burning?
    Most likely, your chimney is failing, and even though you probably could line it, I wouldnt without a certified inspection with a recording camera.  The problems you see in the attic, peeling, etc are a sure sign the mortar is long gone, with the chimney to eventually follow.
    Go with the above recommendations and use the sidewall venter.
    steve
  • Gordy Gordy @ 9:27 PM
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    Second Steve's advice

    The brick and mortar has been saturated with condensation from acidic flue gas. Being the chimney is tall, and an exterior one does not help the scenario.

    If you take a screw driver to the mortar I will bet it easily gouges which it should not. It's rotting from the inside out. If not inspect the flue tile at the top it is probably at the very least spalling.
    This post was edited by an admin on February 12, 2013 9:30 PM.
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