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Venting mod con up a (lined) chimney flue?

Just bought a house that needs a new boiler, and I was wondering.

What do I need to do in order to use a two-story masonry chimney with a

mod-con, rather than venting through the side wall?

Reason is that we are sometimes

away for a month or so during the winter, and I don't want to have to

worry about snow blocking an intake or exhaust pipe, the boiler shutting

down, and the pipes freezing.

There are two flues in the chimney, one for a rarely used fireplace,

and another for the old oil burner I need to replace. It seems to me it

ought to be possible to run a couple of stainless steel pipes through

one flue for intake and exhaust air.

But maybe I am missing something, because everyone I know with a mod con

has it vented through a side wall, and then begs their neighbors to

make sure the vents are clear when they are out of town during a snow

storm. My new neighbors might not be that nice.

Is cost the issue with venting a mod con up a lined chimney flue, or something else?

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  • Ironman
    Ironman Member Posts: 6,869

    The chimney can be used as a chase, but nothing can vent into it if you choose to do this. S.S. Venting can get expensive.

    I don't understand your conception that a side wall vent will get blocked by snow if it's done correctly. The instructions for horizontal venting specifically state that both the intake and exhaust must terminate above the highest anticipated snow fall for your locality. To accomplish this, you simply turn the pipes up vertically once they exit the exterior wall to a point above the anticipated snow level. Then, Ell the intake over and the exhaust horizontal. My house is done this way and there's never been an issue.

    There are also inexpensive freeze alarms that will call you if the house gets too cold. The Lochinvar WHN has a set of alarm contacts that can be incorporated into an alarm system should the boiler control lock out.

    You're gonna have to forget the chimney if you want to keep your fire place, unless it's in a separate liner.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,451
    Up the chimney

    Do it all the time with polypropylene,no concerns about snow line,clearances and no vapor plume complaints!
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • icesailor
    icesailor Member Posts: 7,265
    Snow Blocks:

    If you live in Massachusetts and your neighbors do too, and they are having problems with the snow blocking their vents, they have been improperly installed and need to be fixed. There should ne no problems with sidewall venting. If you are a licensed Massachusetts Journeyman Plumber or Journyman Gas Fitter, if YOU do the install, YOU must take out the gas permit and you are responsible for it being legal. Otherwise, the gas installer is responsible for the venting.

    Sidewall venting is a lot cheaper than venting through a chimney, But I guess they are both legal. The Mass Board has some specific requirements for venting that can come in to play.

    Good Luck.
  • jonny88
    jonny88 Member Posts: 1,139
    chimney chase?

    i use the chimney as a chase all the time with centrotherm.I just watched a program(this old house) where the plumber used the chimney as a chase but also using centrotherm used the chimney for his fresh air intake.That i have never done and was curious as to whether any one else has.