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Point of use Rheem to replace oil boiler for indirect tank domestic water only?

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Abi
Abi Member Posts: 2
edited October 2023 in Domestic Hot Water
Is it possible to use point of use .6 GPM tankless on a closed loop combine with HTP 50 gal indirect tank to get hot water for domestic showers and kitchen.

I have 90k btu a burnham boiler that is on last leg though we just replaced indirect tank 1 year before so it’s fairly new. HTP 50 gal. For heat we have 72k btu air sourced heat pump upgrade upcoming. Trying to determine what would be least expensive method to replace oil boiler completely to get hot water. I fall in zone 5 New York State WestChester county.

So is it possible to add Rheem 3.5 kw tankless and route a closed loop water line via tankless that circulates and heat the coil inside HTP tank and HTP aquastat can direct tankless to stay on till tank comes to required temperatures?

I have solar so electric is a better option for me.
Please do let me know is this a good idea or any better suggestions?
Mad Dog_2

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,635
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    Um... well... yeah,, it will work -- after a fashion. You will have about a half hour recovery time on the tank using the bigger tankless (3.5 KW). If I were to do this, I would use the aquastat to control the circulating pump -- which you will have to have -- rather than directly control the tankless (they are controlled by flow through the unit not temperature). You will need a fairly high head pump to get the desired flow -- the head loss through a tankless is large.

    That said. How many separate bath/kitchen/utility groups do you have? I realise that discarding the nice new indirect sort of hurts, but a much more direct solution would be one or more tankless units directly feeding the various points of use. There would be little or no difference in total energy use, if that is a concern.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    AbiMad Dog_2
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,917
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    I think it’d be easier to install a separate 50 gallon electric tank by the time it’s all said and done 
    AbiMad Dog_2
  • Abi
    Abi Member Posts: 2
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    Thanks for the suggestions

    Agreed it does hurts to discard fairly new indirect tank. But going with new electric tank may be the way to go.
    Hot_water_fan
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,917
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    You might find someone to resell it to. Tankless heaters shine when you have limited space and cannot fit a tank. Otherwise, they have limited value. 
    Mad Dog_2