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Con Boiler Chimney Lining.

Is the combustion air intake (also the exhaust) a "minimum" of 12" inches above the anticipated snow load of your area?

Robert O'Connor/NJ


  • Dave Stroman
    Dave Stroman Member Posts: 763

    This is a typical job where the 2 PVC pipes from a condensing boiler run up the chimeny. I only vent these boilers through the wall as a last resort. It is not possible to use a concentric vent kit on these jobs because each pipe is about 40' long and are suspended from the top with riser clamps. It has always been a problem for me to make the 2 pipes that come out the top look good. Here is what I came up with. It is a home made version of a way to prevent cross contamination and still look good.

    The top is covered with sheet metal. The double ell serves 2 purposes. 1- It keeps the hail we get around here from knocking out the cheap plastic screens they send with the Trinity boilers. 2- Allows wind to pass right through it instead of causing any pressure against fan.

    Dave in Denver
    Dave Stroman
  • tk_3
    tk_3 Member Posts: 36
    vent terminations

    What do the inspectors think? Code states you can only use the terminations OK'd by the manufacturer. The termination they supply and/or suggest is what the product is certified for. Certification for venting is tough and I understand must not be deviated away from. Our codes guy is real tough on venting here. If not in manual must have a letter from manufacturer. Thoughts
  • Snow depth,

    If you look at Dave's second photo, it shows the location of the top of the chimney. If Dave is not above the snow level with that install, (looks like about 20 feet high) that HO is going to be in real serious trouble when it snows. That vent will be the least of his problems.

    Also, heaterman makes a very valid point about the mfg, requirements for the venting. Even though the system that Dave has devised may work very well, if it is not approved by the manufacturer for the product as listed, technically it would not be allowed by code.

    Virtually all codes state that you must follow the manufacturer's installation instructions, which means that you have to install the product per the listing obtained by the manufacturer for that product.

    It is a nice looking install, however to CYA, I would contact the mfgr and get something in writing from them that the install you have done is accepted and approved by them, for the product as listed.

    If they refuse, you could be on the hook if something goes wrong in the future. Also, if there is a problem that you many not be anticipating,they may be able to point it out to you

    Just a thought,

    Ed Carey
  • D107
    D107 Member Posts: 1,849
    Is their facing in different directions a problem for

    maintaining an equal pressurization (from prevailing winds etc.) for both intake and exhaust?
  • Dave Stroman
    Dave Stroman Member Posts: 763

    Thanks for all the input. I agree that this installation would not be sanctioned by the manufacturer or the building department as the manual would not allow for this. If the inspector call me on this, I will have to do something else.

    Snow could possibly be a problem if the snow happened to build up on the edge of the brick chimney. It would have to be a very heavy snow with no wind for that to happen.

    The problem I am trying to over come is the appearence. If I were to extend the exhaust pipe up and bring the air intake pointed down to achieve required separation, the result is not acceptable to many HO, as well as the historic committee in this neighborhood.

    I had one job where I took the exhaust out the top, and brought the air in from the side wall. I actually had the Trinity boiler guys at the factory say that it was ok and they have done it so many times it will work fine. My inspector never questioned it. I know the manual states that you should not do that, but it does solve the separation and appearence problem.

    Attached is a photo where it took only the exhaust out the top. I capped the brick and extended the PVC about 8" above it. I can hardly see it from the ground. You can see that anything else would look terrible in the historic house. I guess the worst thing that can happen is I will have lock out problems and I will have to change it. I guess I'll consider this an experiment and a chance I am willing to take.

    Dave in Denver
    Dave Stroman
  • Robert O'Connor_12
    Robert O'Connor_12 Member Posts: 728

    The venting configuration as shown is a flat capped masonry chimney with a rectangular screened area housing on it for an air intake/exhaust serving a condensing boiler. Mr. Stroman has suggested that this is a Trinity, and if you look at Trinity's installation instructions you will find a venting scenario similar to what was posted. The manufacturer's installation instructions as well as the Fuel Gas Code supports my concern about the minimum termination being 12" inches above the anticipated snow load. I know you may believe this concern would or could be outrageous, but never the less it is a position supported by both the manufacterer and the code thus having stability. The capping off of the existing chimney leaves "just" enough flat area around those terminations, and "if" the conditions were just right such as a heavy snow fall with little to no wind could potentially be a problem. More than likely this would not be a health risk (I would hope not) but rather an appliance performance situation. I know I wouldn't be the one going way up there clearing away the packed snow or ice.

    Robert O'Connor/NJ
This discussion has been closed.