How to connect multiple appliances to Oil Supply

Discussion in 'Boiler Forum' started by daleleelee, Sep 12, 2009.

  1. daleleelee

    daleleelee New Member

    Messages:
    2
    Location:
    Northern NY State
    I have a 275 gal. inside #2 tank with a standard boiler for heating the house and dom. HW. Last year, I installed a toyotomi heat on demand water heater and disconnected the boiler's tankless coil. When I connected the toyoyomi to the oil tank, I just put a tee in the oil line coming out of the filter and ran a second line to the toyotomi. I have had no problems with this setup whatsoever, even with both appliances running at once.

    Now, having finished my basement over the summer, I installed a toyotomi OM-22 oil space heater in the new basement room. I added another tee in the oil line at the tank for that connection and ran a line approximately 60 feet. Now, I am having a problem. When the OM-22 is running and the main boiler kicks on, the om-22 will shut down with an error. I am pretty sure that the main boiler is pulling fuel out of the supply line to the om-22. I hit the reset valve on the om-22 and it will start right back up.

    Is there a specific way that multiple appliances should be connected to the fuel tank? Should a check valve be used? Any help would be appreciated.
  2. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,143
    Location:
    South*East
    Place a check valve on each line as close to each burner as possible. This will prevent the oil from being pulled out of the oil pumps on the burners that are sitting idle.

    John
  3. flamefix

    flamefix New Member

    Messages:
    71
    Location:
    Exeter, England
    I agree a check valve should help you. I would suggest however that you place it in the oil line close to the tank. The reason for this is that it keeps the oil pump and feed oil line to the pump primed rather than just the pump.

    I calculate roughly that you are pulling 2.215gal/hr max with all three units running just check that your oil line is sufficient to supply that.
  4. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,143
    Location:
    South*East
    If he takes your advice he must use three check valves . One on each line. If not when one burner comes on it can pull the oil from the other lines. When I read his post I didn't see that he cut the tees in at the tank.

    John
  5. flamefix

    flamefix New Member

    Messages:
    71
    Location:
    Exeter, England
    Yes that would be correct.

    You also want to be aware of:
    http://no.varme.danfoss.com/PCMPDF/DKBGPG010A702.pdf

    How various resistances in the suction line affect the
    pump
    If fuel oil is subjected to too strong a vacuum, amounts of air and oil vapour
    will separate from the oil. The effect will be noticeable and detrimental to
    burner operation.
    In suction lines oil is subjected to vacuum
    The more valves, filters, pipe bends, etc. there are in a suction line the bigger
    the resistance to be overcome by the pump and the higher the vacuum in the
    line. The oil can thus be subjected to high vacuum with the risk of air
    separation.
    If air separation does occur it can produce oil pump whine and the flame may
    become unstable and disappear. The phenomenon often manifests itself when
    vacuum in the suction line lies at approx. –0.5 to 0.7 bar.
    Therefore, the suction line must contain as few joints, bends, valves, filters, etc.
    as possible – not least if the tank is a long way below the oil pump.
  6. daleleelee

    daleleelee New Member

    Messages:
    2
    Location:
    Northern NY State
    Thank You

    Gentlemen,

    Thank you both very much for your advice. I thought that a check valve in each line would help, but I wanted to confirm that.

    Flamefix, when you say to check that my oil line is sufficient size for 2.215 gal/hr. what size line would you recommend?
  7. flamefix

    flamefix New Member

    Messages:
    71
    Location:
    Exeter, England
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