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Oil Furnace, vented through an old brick chimney with a clay tile liner. Not good enough right?

preserved
preserved Member Posts: 7
Hi everyone. Homeowner in NH. I'm looking at replacing my 25 year old oil furnace, and now that I'm focusing on it I noticed that the exhaust of the current furnace is vented up through the one of the chimney flues. Hard to see what's going on from the bottom, but up at the chimney top there's just the square clay liner which vents the furnace.

Does this install need a SS liner top to bottom? Obviously the exhaust gases are wicked corrosive; the cast cement chimney cap on top is disintegrating.

Thanks!

Comments

  • STEVEusaPA
    STEVEusaPA Member Posts: 5,974
    It depends. For starters you could replace it with a boiler that is direct vented and avoid the chimney all together. Energy Kinetics si one that offers that option.
    It also depends on the integrity of the chimney. Only a chimney pro can answer that after a camera inspections. And btw, they usually say you need one. But they may uncover the chimney is structurally unsound, in which case a line isn't going to help.
    But you probably need one anyway. Depending on the size of the existing opening, and what is need for the new boiler, and the new lower stack temperature, I would probably recommend a chimney liner. Especially if you're firing a new, properly sized (from a heat loss) boiler. It probably only needs a 5 or 6" liner and your old chimney could be much larger.
    steve
  • HVACNUT
    HVACNUT Member Posts: 4,864
    I only ask this because there's often confusion in the type of system. And its been heavily debated, although light heartily among the pros here.

    Are you asking about a furnace as you stated? Warm air heat with ductwork?

    Or a boiler? Hot water or steam heat?

    If you can post some pics of the existing system, make and model, and what you're needs are (efficiency, zoning, DHW) with the new system, we can get a better idea of what your options are, and we can help towards a happy heating system.
  • preserved
    preserved Member Posts: 7
    Thanks guys. Yes, this is for a #2 heating oil hot air furnace, with ductwork.

    The current furnace is an Olsen FBL. I think it has a 1.2G nozzle but I may be wrong on that. If so, that's 117K BTU for my 2400sq foot house.

    Oil is king up here in northern NH, even though I like the idea of a pellet furnace, costs are still prohibitive.

    The existing furnace was built on 1992, not sure when it was installed. Olsen still makes the same furnace with the same physical dimensions. My plan was to just swap out the old furnace for the new one of the same model.

    Currently the exhaust is a 5 inch (I think) pipe running into the bottom of my chimney. I live in a center chimney cape. At the chimney top looking down I see just clay tiles lining the brick. The clay tiles are large, maybe 10x12".

    I don't think I have a good way to power vent out a side wall. My basement is a granite block lined hole, with timber frame sills on top, then living space. No good place to put a hole anywhere near the furnace. The nearest wall that would work would be 30 feet away, and then I'd need to go through a cement foundation, turning a corner or two.

  • STEVEusaPA
    STEVEusaPA Member Posts: 5,974
    First I would do a heat loss to determine if you even need that size furnace.
    And if the chimney passes inspection, I would line it with the proper size liner.
    What are you doing for hot water? If it's oil are you using the same chimney?
    steve
  • HVACNUT
    HVACNUT Member Posts: 4,864
    A 1.20 GPH nozzle is 168k input.
    On today's furnaces with minimum efficiency requirements, it will put out a lot more than 117k net. Don't go by what's there. Like @STEVEusaPA said, do a proper heat loss calculation.

    Is there A/C attached? You might be able to get a lower BTU furnace, but with a 5 ton drive for A/C.

    Interior chimneys usually hold up fairly well, but get it checked anyway.

    And with any warm air system, I always recommend a quality steam humidifier.
  • j a_2
    j a_2 Member Posts: 1,801
    Just have the chimney cleaned, and put a cap on it....Is it required, that depends on the manufactures recommendations and local codes....Is it the best thing to do, I guess so, but if tiles are intact I would go with it...I saw guite a few lower tile sections just loosen up and drop, not a good thing..And even with a liner a dropped lower tile section is not good
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,974
    .
    j a said:

    Just have the chimney cleaned, and put a cap on it....Is it required, that depends on the manufactures recommendations and local codes....Is it the best thing to do, I guess so, but if tiles are intact I would go with it..

    I think you're asking for problems with a modern boiler/lower stack temps, firing into a 10X12 (oversized) chimney, without a liner.

    steve
  • j a_2
    j a_2 Member Posts: 1,801
    I agree, about size of liner, ''tis why I suggested going by manufacture instructions, that's a no brainer,don't you think...? 10 by 12 liner is not very common in residential situations. Wonder who measured it and how