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Electric water heater / Buffer tank

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Snowmelt
Snowmelt Member Posts: 1,418
Existing electric water heater Bradford while , I think 32 gallons , can I use that for a Buffer tank with the hot cold for the space loop & the pressure relief tapping and the drain valve tapping for the boiler loop. Of course I would tee it and put the relief valves and the drain on a tee.

Comments

  • pecmsg
    pecmsg Member Posts: 4,916
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    So the water heater will be used as a boiler?
  • MikeAmann
    MikeAmann Member Posts: 998
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    If you are thinking what I think you are thinking, then NO, there is no separate coil inside of that water heater. It's a tank of water.
  • WMno57
    WMno57 Member Posts: 1,396
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    Mike and pecmsg, He is not thinking what you think he is thinking. The key word here is "Buffer" in the title. I am thinking it will work.
    I DIY.
    Hot_water_fankcopp
  • Snowmelt
    Snowmelt Member Posts: 1,418
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    Mr 57, how would that be piped
  • Snowmelt
    Snowmelt Member Posts: 1,418
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    Yes it will be used as a boiler although they are doing it wrong it’s acting as a boiler now with no P/S
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,906
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    Why a four pipe buffer tank at all? You could do a two-pipe buffer tank too.
  • MikeAmann
    MikeAmann Member Posts: 998
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    OK, enlighten me with a diagram.
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,906
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    Easier with a purpose built buffer tank I’d assume. 
  • Snowmelt
    Snowmelt Member Posts: 1,418
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    So let the water just heat up bottom of tank so it’s in series with the pumps
  • WMno57
    WMno57 Member Posts: 1,396
    edited October 2022
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    I'm not a Pro, this is my guess (greater than sign ">" shows flow direction).
    Boiler Loop
    Boiler Secondary Supply > Water Heater Drain Fitting
    Water Heater PRV fitting > Boiler Secondary Return

    Space Loop
    Water Heater Hot > Space loop input
    Space Loop output > Water heater cold
    I DIY.
  • hot_rod
    hot_rod Member Posts: 22,394
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    What type of flow rate are you considering? You are limited by the 3/4” taps, or the element holes

    Ive connected the two top with fip tube removed. For your bottom, you are limited to the 3/4 drain port. I use a 3/4 male C 1-1/4 copper adapter yeti increase quickly

    You can also use the element holes, typically 1”, you give up some tanks use ability as the are not top and bottom, 6 or so “ up and down, but a large connection, if you are needing 8 gpm or more, use the element holes

    Same method a 1” make X 1-1/4” copper adapter.


    Here are a few that I have built. That Viessmann one was 10 or so
    years ago

    The small 6 gallon has a 4500w element for a 15,000 btu backup heat source

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • WMno57
    WMno57 Member Posts: 1,396
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    I think this would be better though:
    Single Loop
    Boiler Secondary Supply > Space Loop Input
    Space Loop Output > Water Heater Cold
    Water Heater Hot > Boiler Secondary Return
    I DIY.
  • WMno57
    WMno57 Member Posts: 1,396
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    What is the space loop? Will the boiler be heating any other loops? Now or future?
    I DIY.
  • WMno57
    WMno57 Member Posts: 1,396
    edited October 2022
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    The disadvantage to all this is you get the blame if there is a failure in the existing water heater.
    Is the reason for doing this increased buffering capacity or gaining redundant heat sources (WH + Boiler)? Are those benefits worth the additional points of failure?
    I DIY.
  • pedmec
    pedmec Member Posts: 994
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    If your in Massachusetts the water heater as to be specifically design to be used as a heating and domestic hot water source and approved for that purpose by our plumbing board. We replace these type water heaters all the time and its not cheap. These are not long term solutions to your heating system.

    These are installed in managed property. We work with the property manger to replace these. The property manager has something like 500 units in multiple locations with the approved water heaters but we are constantly replacing them. As a developer they are cheaper to install initially but the owners pay dearly in replacements.

    Use the proper materials and equipment for safe operation of your heating system.
  • hot_rod
    hot_rod Member Posts: 22,394
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    Thermo 2000 makes such a product 
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Snowmelt
    Snowmelt Member Posts: 1,418
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    The house is sprayed foamed really good. The boiler is large, but I’m going to say no more then 75 total, also he has 2 radiant floor 1 heated rad and 3 high temp. Later I will ask the btu for the high temp. But I know the low temp is 20-30 thousand btu. I can either do what hot rod said do a 3/4 male to 1 inch male. I know there’s less then 100,000 btu for whole house.
  • hot_rod
    hot_rod Member Posts: 22,394
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    What is your goal for the buffer tank? Longer boiler cycles?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Snowmelt
    Snowmelt Member Posts: 1,418
    edited October 2022
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    Yes he has small zones. Even a towel warmer as a zone , but as you can see it’s not the most organized job