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Can I split an oil boiler for a duplex?

Nina11sue Member Posts: 2
I have a boiler with two large oil tanks in the basement of a sfh. I want to convert to duplex. Can I somehow separate the pipes from the two units so they enter the boiler in different places and put a thermostat in each unit for separate metering of the heat? How is this done?


  • Make sure the system is working well, and keep control of the thermostat, otherwise you may need a second boiler, and control.
    What problems are you having as far with the temperature control in the apartment?--NBC
  • Nina11sue
    Nina11sue Member Posts: 2
    I don't own it yet. I am putting together a scope of work for needed repairs. Assuming it works, would I be able to separate out the pipes and put on two thermostats, one for each unit? If it doesn't work, then I would have to think of other HVAC solutions.

    Thank you for your help.

  • Brewbeer
    Brewbeer Member Posts: 616
    Each apartment can be zoned separately and have separate thermostats controlling their heat. How easy or difficult this is to do, and how much re-piping and related drywall work that might be needed to make this happen, is going to be very difficult to assess without actually getting into the building and looking over how it is currently piped, and how you want to lay out the two apartments.
    Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread: http://forum.heatinghelp.com/discussion/154385
    System Photo: https://us.v-cdn.net/5021738/uploads/FileUpload/79/451e1f19a1e5b345e0951fbe1ff6ca.jpg
    HVACNUT Member Posts: 5,467
    Not something you would tackle yourself. Get an estimate from an installation company, not just a plumber. Somebody who is familiar with zone splitting and controls
    What is your goal? Tenants to pay for their own oil consumption? What provides the domestic hot water? You might be screwed right there.
    And if you want to pipe oil tank "A" to tenant "A"
    and "B" to "B", wiring solenoid valves to open an oil line when a zone calls and stays prioritized until satisfied...
    Like my mentor said 30+ years ago. "Anything can be done. Nothing is impossible. But how much do you want to spend? "
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,373
    Here's my take. Along with the great advice from the others, you'd have to get an estimate to see if it's worth it.
    As an oil heat business owner, I would recommend switching to 2 smaller gas furnaces w/AC, heat pumps or mini splits (if doable).
    Separate the electric, let each tenant pay for their own heat.
    Tenants responsible for their own oil constantly let it run out, and are rough on the equipment. They won't tell you they let it run out, and now the nozzle/filter/oil line are clogged, they'll just call you in the middle of the night and tell you the heat doesn't work.
    If you're converting to 2 units side by side, or 1st floor/second floor, then maybe the piping is ok and only some near boiler piping might need to be modified.
    I would put sensors in the units, and the t'stats locked in the mechanical room.
    But now, your probably oversized boiler is getting less load, will be less efficient, short cycle.
    If the boiler piping is separated in the way you want to make it a duplex, you're cheaper option would be 2 properly sized boilers-and you're not going to find anything small enough with oil.
  • Fred
    Fred Member Posts: 8,541
    Is this a steam or hot water system?