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Finally Ditching the Navien - But Should I Get Another Combi?

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blallik
blallik Member Posts: 3
edited May 12 in Gas Heating

First post, I am a high school art teacher and ambitious DIYer with enough sense not to try and install my own boilers.

I had a Navien combi CH210 put in 14 years ago that has finally failed after several repairs. Having learned on this forum about short-cycling, condensing temperatures, and Navien in general I am thinking of going another direction: maybe a smaller wall-hung boiler and separate heat pump water heater, or else an IBC combi.

An advantage of the heat pump water heater would be dehumidification of the basement, and I have an unused 240 circuit available, but of course it is also very large and complex appliance that is prone to failure.

The IBC turn-down ratio isn't as good as the new Naviens, but they aren't Naviens… 3-way valves, dripping plastic waterways, etc.

Some of you recommend a zoned storage tank instead of the combis, but am I wrong in thinking that those will also corrode, and would be ultimately less efficient than the heat pump hybrid? Our hot water needs are not excessive.

Very much appreciate any thoughts that you folks might have on the matter…

Comments

  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,110
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    Look in to a Viessman Vitodens wall hung and a Vitocell indirect Storage tank. You can do "no betta" than that set up. Mad Dog

    blallikSuperTechGGrossmattmia2
  • kcopp
    kcopp Member Posts: 4,443
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    I am a huge fan of the IBC boilers.

    The Superflow is a solid unit.

    What are your hot water needs?

    blallik
  • blallik
    blallik Member Posts: 3
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    Thanks for your comments… We have 3 baths but soon it will be just the wife and I here, and on different schedules. We rarely if ever try to run hot water to two or more places at a time.

  • psb75
    psb75 Member Posts: 845
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    I believe combi boilers in general are a compromise. But if you are hardset on a combi get a Viessmann 222F. Your idea of a heating boiler and a heat-pump water heater is also good, especially since you have a ready circuit for it. And for summer help in dehumidification. Keep in mind that the installer is the most important part of the formula—for proper design, sizing, installation and SERVICE.

    blallik
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,624
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    I would not use a HPWH. For you small usage there will be no savings and they are complex and prone to fail. And when it does fail who do you call? Most plumbers don't know refrigeration although a few do. They will become a throw away appliance like a microwave or a window AC. Can they be fixed? Probably but not worth the time and expense when your paying for it. Use a mod con boiler and a small indirect. 30 gallons is probably plenty with two people and cautious use. Otherwise use a 40. Indirect have a pretty good life span.

    Mad Dog_2blallikSuperTech
  • psb75
    psb75 Member Posts: 845
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    None of the HPDWHs have compressors that can be "worked on." If the compressor goes…the whole unit goes. A 10 year warrantee is your friend.

    kcoppblallikSuperTech
  • hot_rod
    hot_rod Member Posts: 22,260
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    A small mod con, maybe a 50, and a hpwh if you are down to two in the family

    Check for incentives at wwwdsireusa.org

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,110
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    But, think about the next owners...you may plan on being in the house for another 20 yrs, but you know how life is. I wouldn't put anything in that couldn't provide 4 adults with hot water, but that's just me. Mad Dog

    GGrossjringel
  • PC7060
    PC7060 Member Posts: 1,174
    edited May 16
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    agree this is optimal but I don’t think I’ve ever had a house that could provide hot water for 4 adults even assuming two of the adults are on a friendly basis! 😂

    What is the typical baseline for new house construction? I’m thinking 2 showers at one time would be a stretch for most homes.

    blallikAlan (California Radiant) Forbes
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,624
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    Most anyone can get by with a 40-50 gallon indirect without an issue

    blallikLarry WeingartenSTEAM DOCTOR
  • blallik
    blallik Member Posts: 3
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    Well, the only installer who can do the job fairly soon does IBCs, and recommends staying with a combi. No load calcs required, they "always install 199s" because the smaller ones can't keep up with HW demand in cold weather. I asked if a smaller boiler with indirect tank would be more efficient and they say no. Veissman installers are booked into July. Thinking of putting down a deposit… Thanks again for your thoughts!

  • Alan (California Radiant) Forbes
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    Too bad; @psb75 suggested the V. 222-F and is a great option if you have the room since it has a 26.5 gal. storage tank. IBC is good, not great. Lochinvar is better. Why? Fewer problems. All three have great tech. support.

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    blallikMad Dog_2
  • kcopp
    kcopp Member Posts: 4,443
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    I have the Superflow in my own place. Works well.

    I would do the SFB and a 40 indirect. Pretty solid.

    If you want to upgrade the VX is super nice.

    But thats me.

  • mattmia2
    mattmia2 Member Posts: 9,747
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    Though it is very possibly true that a combi smaller than a 200,000 btu can't keep up with a moderate DHW demand in your climate, the fact that they don't know how to install an indirect is a red flag. Find someone else. HTP and Lochinvar also make good stuff.

    GGross