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On-Demand Water Heater

I have a 50 gallon, gas, Kenmore water heater. It is slightly leaking from the bottom. It's past its useful life by about 3 years (installed 2009 with a 9 year warranty).

I'm considering replacing it with an on-demand unit like Rannai. Does anyone have any experience with this brand or any other brand...pros/cons of on-demand versus traditional tank.

Thanks!

Comments

  • Intplm.
    Intplm. Member Posts: 1,404
    edited November 7
    The brand Rinnai is what I use. Many others out there are good.
    Properly sized for your needs is best.
    Water quality supplying the unit can be a concern, ie. well water, which might be an issue.
    I like that one demand is truly on demand. Runs when you use it.
  • The only time I recommend an on-demand water heater is when there's no space to install a tank-type heater or when there is a large bathtub or a large hot water demand that a tank-type water heater can't keep up with.

    Your Kenmore will work when there's no power; not true for an on-demand. And tank-type water heaters have almost nothing that goes wrong with them; they're very straightforward.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
    Intplm.
  • Larry Weingarten
    Larry Weingarten Member Posts: 2,702
    Hi @rosaliedipietro2 , I agree with all of the above. I'd like to add that as the US moves away from fossil fuels, it can make sense to consider going with heat pump technology as appliances are replaced. There will be substantial rebates next year, though you can see what's available to you now at www.dsireusa.org . In general, tank-type heaters require far less maintenance than tankless, deliver hot water faster and the overall cost to own and operate is the same or lower. Lastly, do you need endless hot water, or enough hot water? :p

    Yours, Larry
    Alan (California Radiant) ForbespecmsgJERRYMACHODGE_2
  • mrhemi
    mrhemi Member Posts: 21
    Don't do it.
    Licensed Steamfitter.
    Licensed Instrumentation & Control Technician.
    SuperTech
  • hot_rod
    hot_rod Member Posts: 17,531

    Hi @rosaliedipietro2 , I agree with all of the above. I'd like to add that as the US moves away from fossil fuels, it can make sense to consider going with heat pump technology as appliances are replaced. There will be substantial rebates next year, though you can see what's available to you now at www.dsireusa.org . In general, tank-type heaters require far less maintenance than tankless, deliver hot water faster and the overall cost to own and operate is the same or lower. Lastly, do you need endless hot water, or enough hot water? :p

    Yours, Larry

    Until the HPWH breaks down!
    Most plumbers do not have refrigeration skills or tools. Probably a toss up on repair costs and life expectancy, tankless to HP.
    But I will go with a HPWH when my tank fails😚
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    JERRYMACHODGE_2
  • Hot_water_fan
    Hot_water_fan Member Posts: 892
    Pros: tankless takes up less space, generally shinier. 
    Cons: heating water on demand doesn’t make much sense, it’s a solution in search of a problem. You can get the same size burner and same efficiency with a gas tank, and much higher efficiency with a heat pump water heater. 
  • Larry Weingarten
    Larry Weingarten Member Posts: 2,702
    @hot_rod said: Until the HPWH breaks down!
    Most plumbers do not have refrigeration skills or tools. Probably a toss up on repair costs and life expectancy, tankless to HP.
    But I will go with a HPWH when my tank fails😚

    Absolutely! The things that can help with this are to either replace the sacrificial anode in the HP tank regularly, or install a powered anode. A surge suppressor can't hurt either. Also, solar preheat, drain heat recovery, fixture and piping system efficiency all add up to being able to deal more easily with HP problems when they come up. At a minimum, these things buy time. The real trick here is to find simple and durable equipment for a system that meets the hot water needs. A pot on the stove has worked, but lacks some in convenience. :|

    Yours, Larry
  • hot_rod
    hot_rod Member Posts: 17,531

    @hot_rod said: Until the HPWH breaks down!
    Most plumbers do not have refrigeration skills or tools. Probably a toss up on repair costs and life expectancy, tankless to HP.
    But I will go with a HPWH when my tank fails😚

    Absolutely! The things that can help with this are to either replace the sacrificial anode in the HP tank regularly, or install a powered anode. A surge suppressor can't hurt either. Also, solar preheat, drain heat recovery, fixture and piping system efficiency all add up to being able to deal more easily with HP problems when they come up. At a minimum, these things buy time. The real trick here is to find simple and durable equipment for a system that meets the hot water needs. A pot on the stove has worked, but lacks some in convenience. :|

    Yours, Larry

    I wonder if all of them can be run in resistance element mode only, if a compressor fails?
    Although a control board failure may prevent that anyways
    I’ve heard pretty much all appliances these days are built around a 10 year life expectancy. And parts will be obsoleted after 10 years anyway.
    Had to but a new refrigerator this week, salesman claims all their vendors say 10 years is the target for manufacturers.

    The compressor on the HPWH I have is about the size of a soup can 🤓
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • psb75
    psb75 Member Posts: 610
    I've installed well over 25 heat pump domestic tank water heaters (three brands: Brad. White, Rheem, State/A.O.Smith). I've had two with the compressors crapping- out. One "let go of" its refrigerant. According to tech support there "is no fix. Scrap unit and get new one under warranty." When the compressor "goes" on these units...they default to the electric induction heating elements. It then...becomes a PLAIN OLD ELECTRIC tank water heater. I have also replaced 4 or 5 control panels that "just go dark." The companies will make good on parts and whole unit warranty issues BUT...THEY DON'T PAY FOR MY SERVICE CALLS AND LABOR! I'm feeling like NOT installing them anymore.
    kcopp
  • HomerJSmith
    HomerJSmith Member Posts: 1,815
    edited November 23
    HPWH "a trend for the future", maybe not. The Green agenda will certainly love them, after all they aren't pouring green house gases into the atmosphere.

    What's missing in the equation is the cost and energy used in manufacturing. That includes the raw materials, finished material goods, transportation costs, maintenance costs, repair parts costs, and initial purchase and installation costs. Complicated systems are prone to breakdowns and failures. I will go with simple, which is conventional W/H, gas or electric.

    I have some National brand w/h that are going on 30 yrs. That's the best heater ever made other than Hoyt Copper Heart heaters, 50 yrs.

    I think HPWH is like a variable rate morgage with a balloon payment. Initial savings with a gotcha down the road.

    Of course, if our masters eliminate nat gas or LP, we may be stuck with paying the exorbitant costs, won't do much for the environment, but will sure make the manufacturers rich. We can all drive electric cars, if you can afford it. hahaha! You will never see a electric Yugo. By the way, do you know how to double the value of a Yugo? Fill the tank with gas.