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How to properly calculate oil burner size

uncndl1
uncndl1 Member Posts: 4
We want to replace our hot water oil burner system and have gotten 3 quotes.
Each contractor has provided quotes and said we need a certain size.
They are all different and we don't want too small or too large.
We have 72 feet of baseboard (zone 2)
And 6 radiators in the original 70 year old farm house (zone 1)
Replacing a 40 year old HS TSRM OT 35 COMBINATION OIL & WOOD SYSTEM.
This is a large expense and don't want to get too small and be cold or too big and waste money.
We want a non condensing oil burner boiler with 2 zones

Comments

  • HVACNUT
    HVACNUT Member Posts: 4,215
    Did anyone do an actual heat loss calculation?
    What equipment was offered?
    Most here will agree that for oil, a 3 pass boiler with an indirect water heater or the Energy Kinetics System 2000 is the way to go.
    Some manufacturers allow for up to 3 different firing rates for a specific boiler.
    But if nobody did a heat loss, then you need to get estimates from different companies.
    Where are you located?
    GBart
  • Jamie Hall
    Jamie Hall Member Posts: 17,190
    The only way to do it for hot water heat, such as you have, is to determine the heat loss of the building on a design day. That's the size boiler that you need. It's not hard to do, and any competent contractor should have done it.

    From there you determine what the required water temperatures are based on the radiation available -- that's your baseboards and radiators. But that comes after the heat loss calculations and determining the boiler size.

    If none of your contractors did a heat loss -- as @HVACNUT says, get a different contractor.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    GBart
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 10,397
    @uncndl1

    download the "Slant Finn" app and do your own heat loss.

    Keep searching for a contractor that will do a heat loss. Then you can check his #s against your calculations. The slant Finn program is easy, it will probably take you an hour or two to understand it and punch the numbers in. It's the only correct way to do it with hot water heat. 72 ' of baseboard will put out about 44,000 btu/hr
  • uncndl1
    uncndl1 Member Posts: 4
    Thanks for all your ideas.
    I'll get the Slant Finn App and crunch some numbers. That's also a great idea to ask if heat loss calculation was done.
    We're located in upstate NY near Saratoga.
    It's great we have time.
    The previous owners used the wood burner half of the unit. We've only used the oil half. It's working great but I want a 3 pass condensing unit. I'll report back.
    Thanks.
  • pecmsg
    pecmsg Member Posts: 2,362
    Remember your condensing boiler will run lower water temperatures! Is the 72' of baseboard enough with 140° water?
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 10,397
    @uncndl1

    Confused. Your first post says non-condensing the last post says condensing. Since this is oil I wouldn't consider condensing
    GBart
  • uncndl1
    uncndl1 Member Posts: 4
    Non-condensing like we have now is what we want.
    We have one Zone radiators and the second is newer construction baseboard
  • HVACNUT
    HVACNUT Member Posts: 4,215
    Energy Kinetics makes a 90+% non condensing oil boiler called the Resolute. You should look into it. The contractor must be an EK dealer.
    Click on "find a contractor in my area" at the top of the page to see if anyone here is near you.
    GBart
  • uncndl1
    uncndl1 Member Posts: 4
    I contacted EK,
    And called someone they recommend.
    That Mechanical Company said they would recommend a Buderus over the EK.
    Another contractor we got a quote from said they would not install an EK either.
    Appreciate your information.
    We're on a well and I think EK has SS heat exchangers.
    Maybe that's why?
    Thanks
  • GBart
    GBart Member Posts: 746
    Honestly the EK is far more efficient and on homes with well water I just use indirect water heaters.
    SuperTech
  • Jamie Hall
    Jamie Hall Member Posts: 17,190
    GBart said:

    Honestly the EK is far more efficient and on homes with well water I just use indirect water heaters.

    That's as may be. However, if the company in the area which EK recommended recommends something else... that really should tell you something.

    Buderus is an excellent, reliable boiler. If the installer prefers it to brand X in the application, to me that makes it a no-brainer.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England