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  1. #1
    mathew stouffer's Avatar
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    Default Height of furnace vent above grade

    This is an exhaust vent for a high efficiency furnace. As a rule of thumb is there a min height requirement above grade in areas with heavy snow fall. This was 14 inches on the northwest side of the home.

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  2. #2
    Join Date
    Jul 2008
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    Snowbird (this means I'm retired and migrate between locations), FL/MI
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    Default Re: Height of furnace vent above grade

    Is this installed as direct vent or mechanical exhausting? Where is combustion air inlet? It must not be near possible combustion air contaminants, i.e. dryer exhaust terminal.BTU?What's the protection from flooding design criteria locally? R322.1.6/R322.2General rule is termination's bottom/low opening to atmosphere be 12" above snow line (average normal snow liine/anticipated snow level accumulations upon grade plus 12"), a minimum of 12" above grade itself; if terminating through wall, similar indications if terminating horizontally through roof that is above roof line and further...12" above anticipated accumulated snow height upon same), found in manufacturer's installation instructions; further usually indicating avoiding terminations exposed to prevailing winds in excess of 40 mph. Check R301.2 as specific to the location, Mfg's oftentimes reference NFPA 54 either directly or via ANSI number, IFGC similar language. For example 2006 NFPA 54 Section 12.9 through the wall vent termination covers all aspects of both direct vent (12.9.3) and mechanical exhausting (12.9.1 and 12.9.2)."...Additional criteral shall be established by the local jurisdiction and set forth in Table R301.2...."Condensate drainage before terminal?Protection from freezing, protection of surfaces, etc. closing the opening; protection of surfaces, etc. from damage from acidic condensate/exhaust.Guessing that's a dryer exhaust hood in the foreground, and not the supposed combustion air intake with that type of hood, which is also questionably low elevation from grade in snow country and its compromise/obstructions with sidewall protrusion clearances (applied veneer).HE doesn't tell us mechanical exhaust or DV equipment installed as DV.Furnace's llisted installation instructions, and listed vent materials/system approval conditions/instructions.Check/Look up for the specifics relating to the lot/locale in re: design criteria in re winds, altitude, flood , freezing/temps protection and normal/average snow accumulation data.HTH


  3. #3
    Join Date
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    Default Re: Height of furnace vent above grade

    Quote Originally Posted by mathew stouffer View Post
    This is an exhaust vent for a high efficiency furnace. As a rule of thumb is there a min height requirement above grade in areas with heavy snow fall. This was 14 inches on the northwest side of the home.
    Ha I love it!

    The only time the snow will be 14" deep in Park City will be June. But then you know that.


  4. #4
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    Feb 2008
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    Default Re: Height of furnace vent above grade

    Didn't someone ask this question in another thread?
    I believe the minimum is 18" above grade.

    The fact there is snow on the ground is indication to me that drifting snow is a possibility.


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