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Thread: Navien 180 ASME GAS COMBO Boiler/Hotwater heater

  1. #1
    DIY Junior Member pkboulos's Avatar
    Join Date
    Jun 2013
    New York

    Default Navien 180 ASME GAS COMBO Boiler/Hotwater heater


    i am renovating a lofted one bedroom space maybe 600 sq feet above 2nd floor of a carriage house. i want to purchase this unit but i am worried it may be "too big" for the space?

    i would use it for baseboard heat and hot water... would there be any downside if it was too big? it says min output BTU of 17,000k... I dont have a lot of knowledge about this and need some help.

    I need to use gas as a i dont have enough electric for baseboard heating, i like the idea of on demand because i dont know how often i will actually be using the space of it i may rent it or what.

    thank you

  2. #2
    In the trades Dana's Avatar
    Join Date
    Jan 2009


    For a 600 loft in NY I'd think a cheap 110V 3/4 ton mini-split would be a more appropriate choice for heating since it cools too!

    They all draw less than 10amps, and put out more than 10,000BTU/hr at +15F (NYC's 99% outside design temp.) If that's not enough, the 1- ton versions draw about 10A.

    The gas plumbing for a monster burner like the Navien is critical and you may need to upgrade the regulator if you have other big burners on your gas system. At 17,000BTU at 130F average water temp it takes 60' of baseboard to balance, and at 120F AWT it would take about 75'. If you go with much less than that you'd have to crank the temps well above the condensing range to keep it from cycling the burner on/off.

    Start by calculating the heat load on the place, THEN you'll have a better shot of figuring out what it takes to heat it. If it has insulation in the walls/ceiling/floor and glass in the windows it probably won't be anywhere near 17,000BTU/hr anyway.

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