Tankless Water Heater Venting

Discussion in 'Water Heater Forum, Tanks' started by Greenthumb77, May 12, 2021.

  1. Greenthumb77

    Greenthumb77 New Member

    Jan 11, 2015
    My old gas water heater was replaced with a Navien gas tankless NPE 240A2.

    The old water heater was located in a small closet that was built into the outside of the house that has a door with a vent screen in it. This is where the Navien was installed.

    Instead of venting it with pipe and connecting to existing venting through the roof the installer used a Navien outdoors venting accessory. Navien 30010604A Outside Vent Kit.

    I live in Roseville CA. Has this installation been done correctly according to code? Is this closet truly outside? I read somewhere an outside installation must not have a roof over it etc.

    Thank you guys for your advice
  2. Bannerman

    Bannerman Well-Known Member

    Mar 19, 2014
    Ontario, Canada
    If your old WH was a tank type, depending on capacity, the old one may have had a 40,000 BTU burner whereas the Navien has a burner that supports up to 199,000 BTU and will require substantially greater combustion air. Depending on the grill size and the grill's air flow capacity, the exsisting grill maybe sufficient, but that should be verified.

    Because your tankless WH is located within an enclosed space, the exhaust gasses will need to be exhausted through piping to the exterior with the required minimum distance between the exhaust termination and the combustion air intake opening. Because the Navien is a condensing unit, plastic exhaust pipe will be needed, but the pipe is not required to be routed through the roof but maybe terminated through an exterior wall

    The Outdoor Vent Kit is suitable for mounting the WH on an exterior wall only where there will be no enclosure around it. When there is no enclosure or roof above, the exhaust gases exiting the vent kit will dissipate to atmosphere, but your enclosure will cause products of combustion to accumulate.
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  4. Dana

    Dana In the trades

    Jan 14, 2009

    As long as both the exhaust and combustion air are piped to the outdoors with the requisite sized pipe, and not exceeding the length limits in the installation manual (= less than 75 feet of 2" PVC) the primary code issue would be the distance between the exhaust termination and any operable windows or ventilation air intake vents on the house. See the diagram on page 46 (p.47 in PDF pagination) in the manual. Review all details regarding the air intake and exhaust venting to verify whether the installer did it by the book.

    With the combustion air piped to the outdoors it's fine (even preferable) to seal up the vent screen in the door and insulate the water heater closet. The 99% outside design temp in Roseville CA is 39F, but it can experience hard freezes at least a few times per decade.
  5. breplum

    breplum Member

    Oct 2, 2004
    Plumbing and heating contractor
    San Francisco Bay Area
    Bannerman said it all correctly.
    Your Navien is NOT installed correctly.
    That outdoor cap only is designed to work in a wall hung exterior wall with clearance to openable windows of four ft.
    Dana likes this.
  6. fannierwade

    fannierwade New Member

    May 17, 2021
    3805 Diane Street Los Angeles
    I’ve been questioning installation in my attic to exit my roof and watching some tons of videos but convinced me to vent out a side wall with confidence.
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