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Adding an electric hot water heater to my oil boiler for domestic hot water

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  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,053
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    NAmenta said:

    Thank you for your detailed response Ed. It definitely helped a lot and everyone else who gave their input too. Yeah my last place was the bottom floor of a 2 family built in the 1800s. Only shared ceiling but the place had terrible to no insulation and very drafty doors and windows.

    So a couple dumb queations....can you explain cold start to me (pardon my ignorance on this) and is there a way to slow or cut down the heat loss from my chimney without killing us with carbon monoxide?

    Thank you again!
    Nick

    I think @Jamie Hall answered your query about the cold start and slowing down the heat loss up the chimney. i just want to further explain... You have a boiler that maintains a water temperature all the time. maybe about 160°. This minimum temperature is there 24/7 so if you want to take a shower at 2:00AM your cold water will flow thru the tankless coil in your Hot Boiler and come out at a reasonably warm temperature so you don't get a cold shower.

    If you can store say 30 or 40 gallons of hot water in a well insulated tank, then your heating boiler that is connected to the chimney can turn off if there is no call for heat and the tank is full of stored hot water (that is not connected to the chimney vent). In the summer, when you don't use any oil for space heating, the boiler can get cold and less heat will be vented up the chimney. this results in less wasted heat up the chimney. We refer to that wasted heat "Down Time Loss". Cold start boilers have a much lower Down Time Loss when compared to a boiler that maintains a minimum temperature higher than the ambient room temperature.

    Mr. Ed

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • MikeAmann
    MikeAmann Member Posts: 998
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    Thanks Ed. This is what I had bookmarked: https://allstategasket.com/info_gasket_material_style-1188.asp
    Unfortunately, my boiler is so old that nobody has a pre-cut gasket for it. But no problem making my own.
  • Robert_25
    Robert_25 Member Posts: 530
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    Try these guys:. https://tricoils.com/
  • MikeAmann
    MikeAmann Member Posts: 998
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    I will give them a shot.
    I had a SS CNC laser cut block-off plate made in case the tankless coil ever fails. I still have the pattern, so maybe they can cut a gasket for it.
  • NAmenta
    NAmenta Member Posts: 17
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    Thank you for your detailed response Ed. It definitely helped a lot and everyone else who gave their input too. Yeah my last place was the bottom floor of a 2 family built in the 1800s. Only shared ceiling but the place had terrible to no insulation and very drafty doors and windows.

    So a couple dumb queations....can you explain cold start to me (pardon my ignorance on this) and is there a way to slow or cut down the heat loss from my chimney without killing us with carbon monoxide?

    Thank you again!
    Nick

    I think @Jamie Hall answered your query about the cold start and slowing down the heat loss up the chimney. i just want to further explain... You have a boiler that maintains a water temperature all the time. maybe about 160°. This minimum temperature is there 24/7 so if you want to take a shower at 2:00AM your cold water will flow thru the tankless coil in your Hot Boiler and come out at a reasonably warm temperature so you don't get a cold shower. If you can store say 30 or 40 gallons of hot water in a well insulated tank, then your heating boiler that is connected to the chimney can turn off if there is no call for heat and the tank is full of stored hot water (that is not connected to the chimney vent). In the summer, when you don't use any oil for space heating, the boiler can get cold and less heat will be vented up the chimney. this results in less wasted heat up the chimney. We refer to that wasted heat "Down Time Loss". Cold start boilers have a much lower Down Time Loss when compared to a boiler that maintains a minimum temperature higher than the ambient room temperature. Mr. Ed
    Mr Ed, thank you for taking the time to give me the detailed explanation. It's much appreciated!

    Nick
  • NAmenta
    NAmenta Member Posts: 17
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    Next question....and maybe a dumb one to you all who do this for a living. What type of pipe should I use to tie this all in per the diagram posted above? Copper only? Thanks guys
  • Jamie Hall
    Jamie Hall Member Posts: 23,428
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    Could use either copper or PEX (crimped!) for domestic hot water. There are advantages to both.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • NAmenta
    NAmenta Member Posts: 17
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    Could use either copper or PEX (crimped!) for domestic hot water. There are advantages to both.
    I figured I may be able to use PEX I just wasn't sure the maximum recommended temp for it. Thank you. 
  • MaxMercy
    MaxMercy Member Posts: 514
    edited December 2021
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    Could use either copper or PEX (crimped!) for domestic hot water. There are advantages to both.

    Why crimped necessarily for DHW Jamie?