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Indirect water heater used with a low water volume oil boiler.

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bob eck
bob eck Member Posts: 930
How do I go about calculating the energy savings (how many gallons of oil will be saved) when using a low mass oil boiler cold start and an indirect water heater vs using a steel oil boiler with a domestic coil and keeping this boiler at 180 deg all year long just for domestic hot water.

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  • lchmb
    lchmb Member Posts: 2,997
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    The boiler you have was probably over sized for domestic HW. Size the new boiler based on actual heat loss and add an indirect. I'd consider a system 2000 with storage tank. I tell my customers they will save a fair amount of oil and have never had a complaint...
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,542
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    NORA is revamping the FSA, which is based on Tom Butchers study referenced above. Should be ready in a matter of weeks. I can tell you based on anecdotal evidence, a typical tankless coil boiler using 900-1000 gals per year or thereabouts will use approximately 30% less with a triple pass, indirect, reset control. Larger consumers will see more, lower users less.
    https://noraweb.org/fuel-savings-analysis/
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    kcopp
  • Jason_13
    Jason_13 Member Posts: 304
    edited April 2016
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    I have been doing indirects sine about 1984 and never saw a tankless coil on an oil boiler use less oil than an IWH when comparing year round usage. We always tracked K factors and oil usage.
  • bob eck
    bob eck Member Posts: 930
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    Bob please let me know when this https://noraweb.org/fuel-savings-analysis/ is back up and running thanks
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,542
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    Larger consumers will see more, lower users less.

    Is that on a percentage basis? If so............why would that be?
    Yes, 1000 gallon houses routinely go to 700. 700 gallon houses rarely go to 490
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  • Robert O'Brien
    Robert O'Brien Member Posts: 3,542
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    CH= Heating
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