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Venting condensing gas boiler

Jim100Flower Member Posts: 102
Does anyone know the venting regulations in Massachusetts?

I want a new condensing boiler. Outside from my boiler area is a 4' deck/walkway and small sitting area and doors from the house - if we come through sill plate to the deck, the vent gases might blow into the house in the summer when the boiler heats the hot water, and it  would not be attractive.

A little farther down hill the foundation is exposed with the walkway above. It is a steep slope starting with 5' exposed and ending with maybe 8' exposed. We could bore through the foundation and vent there. How far above the ground does the vent have to be? How far below a deck or balcony does a vent have to be?

I don't want to go up the chimney because we would have to remove one of the two cowls atop the chimney and they are a distinctive architectural feature.

Also, can the vent run within the basement have a U shape in it?



  • bill_105
    bill_105 Member Posts: 429
    edited January 2013
    Does anyone know the venting regulations in MA?

    Holy cow!! Get ready .Here we go!!

    Oh, I forgot Happy New Year
  • icesailor
    icesailor Member Posts: 7,265
    Gas venting in Massachusetts:

    The gas venting in MA is the same as any other state. They follow the appropriate NFPA and also have additions and exceptions.

    NFPA says that you must follow the manufacturers installation instructions. Every installation manual I have seen for venting says that the vent termination must be at least .3 meters or 12" above the grade or above the snow line where applicable. Therefore, in Massachusetts, you must go on-line and find out what the "normal" highest snow total in a large snowfall. It will be listed. If the snowfall level is 17", add 12" and you get 29". The vent must be a minimum of 29" above the grade where the vent termination is.

    You can't vent underneath a deck or porch.

    Any Massachusetts licensed plumber should know because it has been heavily covered in the CE courses we are required to take to keep our licenses. The Board controls the content and approves the courses so that each and every licensed plumber, gas fitter and LP Gas installer learns the same in each education cycle. Each course is approvedby the Board. There was someone who taught plumbing theory for many, many years. The person didn't want to change and teach what the board wanted. The Board took their certification away. You get licensed through the Dept. of Education.  If you pay attention, there is no reason to not know the answers to the venting questions.
  • Jim100Flower
    Jim100Flower Member Posts: 102
    Never under a deck?


    The deck joists are 84" above grade and the decking above the joists, maybe another 10", call it 94".

    Take away 29" to get above snow line and there is 65" of clearance above the vent. Could this work, or is the rule "never under a deck?"
  • icesailor
    icesailor Member Posts: 7,265
    edited January 2013
    84" deck:

    As long as that deck, 84" above the ground, which usually has openings between the boards, doesn't have a door or window within a 48" radius of the vent, it's probably good to go. And it meets code about distances from combustible material.

    And you don't need the plastic sign mounted above the vent so it can be found if it is covered over with a snow drift.
  • Henry
    Henry Member Posts: 996
    Good way to ruin a deck

    Natural gas combustion gases contain a slight acidity with a large amount of humidity. Unless there is a masonry wall or a bad chimney, we will not sidewall vent. I have seen too many damaged wood siding, decks and other wooden structures, caused by sidewall venting.
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