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kochmon Member Posts: 9
Here is my situation. I have three oil burners. One for boiler(baseboard heater), one for hot water heater and one for forced air system. Recently my water heater started leaking and my boiler is oil too(Ford products Cop). I am planning to install a 50 Gal(6 people) indirect hot water heater. What should be the right size boiler(oil fired) to run this indirect water heater? Is there any calculation or chart that i can look up to check out the right size on water heater and boiler? Is 50 gal enough for 6 people(3 adults, 3 children)? I have 2 full bath, 5 sinks that use hot water and the dishwasher. Is it advisable to use indirect to regular oil fired hot water heater? What is best and reliable brand for boiler and indirect water heater?


  • 3 oil burners

    If you can switch to gas, now would be the time to do it. You could attach the indirect to the present oil boiler, and then when the gas line is in, you could get a new gas boiler to handle the heating and hot water. The oil furnace could later be replaced with a hydro-coil, or you could have baseboards in that part of the house.

    This would enable you to use up the oil.--NBC
  • kochmon
    kochmon Member Posts: 9

    Thanks NBC but right now i am not intrested in gas. All i want to know the size boiler that i have to use for 50 gal indirect fired hot water heater and a good and reliable brand that i can install
  • the key to a successful installation

    the most important part is the installer. he will be able to help choose whether to have a high efficiency, or traditional cast iron boiler, and he will know which makes are well stocked with parts locally. if you do not have an installer yet look on the find a contractor part of this site, [search by state not by zip-code].

    the remaining boiler could be supplying you with hot water while you take time to choose the permanent replacement, and don't forget the possibility of a hydro coil to replace the oil furnace when the flag on it's meter comes up.--nbc
  • SWEI
    SWEI Member Posts: 7,356
    Not interested in gas

    Is there no NG service in your area?  Do you work for an oil company?
    EBEBRATT-Ed Member Posts: 13,440
    water heater

    A storage type tank is assumed to be 80% full of useable hot water because as water is drawn the cold water entering cools some of the hot water. So, a 50 gallon indirect will give you 40 gallons of hot water. To reheat 50 gallonsf cold water (100 degree rise) which is considered normal would require a boiler with an out put of 42,000 btu/hour assuming that you allow it 1 hour to reheat the tank.

    Showers are assumed to be 10 gpm/use depending on the showerhead

    dishwasher 7 gpm/use

    washing machine 6-7 gpm/use 

    there are all type of different calculators available on the internet. I would think a 50 gal. indirect with a 50,000 btu boiler would be adequate. my opinion only
  • tim smith
    tim smith Member Posts: 2,544
    Which indirect water heater?

    Depends on the heat exchanger capacity to reject heat to the 50 gals of water in tank. Each indirect water heater mfr has a recommended boiler size for their tank. I would probably go to the 60 gallon indirect, either Superstor SSU60 or the Lochinvar Squire 60 tank. Both stainless tank with either stainless heat x or cupronickel.  I think the 60 can reject appx 140,000 btu or so when the tank is cold, rejection goes down and tank temp and boiler water temp gett closer together. Hope this helps. Tim
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,573
    edited November 2012
    3 oil burners minus 1

    What size is your present boiler?-NBC
  • kochmon
    kochmon Member Posts: 9

    Thanks to NBC, ED and TIM for giving all the advice. Now i know where to start my research. As you mentioned TIM i checked the mfr site but it does not help me in any way or may be I am looking at the wrong thing. What exactly i should be looking for or what term should I be giving more importance on indirect hot water heater and on the oil fired hot water boiler
  • kochmon
    kochmon Member Posts: 9

    Got some information of the old boiler name plate



    MODEL - FD 110  A

    S # - 86  5974

    M.W.P.WTR - 30 PSI

    MIN SV CAP - 154MBH

    S.S 10.9 SQ

    That's all i can make out of name plate of the old boiler.Now what should be the size of the new boiler if i have to installing a 50 gal indirect hot water heater??
  • SWEI
    SWEI Member Posts: 7,356
    edited December 2012
    What should be the size?

    Only a heat loss calculation can answer that.  Has this been done?

    This is not a plug and play project.  Take the time to do the math, or you will get bad results.  In the hands of a competent installer, one properly sized boiler with appropriate controls should be able to handle the whole job -- even if you are doing it in stages.
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