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Community and Q&A

Choosing a Combi Boiler

jenniferz5 | Posted in General Questions on

What are the best propane combi-boilers for a 1400 sq ft Zone 5a (CT) home? A little background… The home was built in 1953, purchased by me seven years ago.  I have replaced and updated so much, including an old oil furnace replaced with a MrCool heat pump minisplit.  For the second time in a year, mice have completely destroyed the motherboard (with their bodily fluids) and eaten the wires.  I need a heater that lives indoors.  As much as I do not want to use fossil fuels, I already have a propane water heater that I could easily replace with a combi-boiler. I see Navien, Rinnai, and Rheem on this forum, any others?  Any personal experience with rads?  I am leaning toward Buderus, but will consider anything. Thank you.

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  1. paul_wiedefeld | | #1

    The installer is much more important than brand. The temptation is to use a tankless water heater (like something found at Home Depot) as a combination boiler - don't do that! Otherwise you'll be fine. A combi is ideal for tight indoor spaces. If you want better hot water performance, a storage tank would work best. You can have a storage tank either independent of or connected to the boiler..

    Sorry about the mice! Is there anything Mr Cool doesn't do that other heat pump makers do? Surely mice cannot be destroying heat pumps nationwide.

  2. paulmagnuscalabro | | #2

    I'm not sure this helps, but I had a Navien combi-boiler installed two winters ago when the 1970 Kenmore NG boiler in the house finally died. Similar home size, about 1,300 square feet but only the main floor (900-ish square feet) is heated. I did have a pump fail in the first two months, but my plumber fixed it the same day at no charge and billed Navien for warranty work. I've used Rinnai before on another house, and it also seemed fine. I guess I'd echo Paul W. above, finding a good plumber's probably more important than brand as long as you're sticking to a "real" brand (like the ones you mentioned).

    Other than that, it's a big upgrade from the 50-year old boiler it replaced... after getting used to instant hot water, it's pretty nice to not worry about how much is in the tank if there's going to be several people showering one after the other.

  3. jenniferz5 | | #3

    I will definitely ask about a connected tank. That sounds ideal. Thank you!

  4. walta100 | | #4

    Before you consider Navian you may want to read this thread.

    Note the YouTube video has been erased from YouTube and likely the web. No doubt some lawyering happened.

    As I recall the video showed clear and compelling evidence of leaking heat exchangers.


    1. jenniferz5 | | #5

      Thanks, Walta.

  5. Expert Member
    Akos | | #6

    What are your local energy costs? Around me propane is about the same cost as resistance heat, you might be better off with a standard resistance tank. This would let you get a cheaper non-combi boiler which avoids all the issues these have especially if you have hard water.

    1. jenniferz5 | | #7

      Can you tell me more? Thanks!

  6. freyr_design | | #8

    Seems like a cheaper solution would be to keep the mice from eating and ruining the outdoor unit. Could you build a cage around the heat pump? Perhaps 1/4” steel wire bird screen and a solid floor.

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