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Excessive oil use

Hi,I have a Bock 32pp oil water heater for heating system,and domestic hot water.It is 18 years old ,and in the last year or so ,oil use has doubled.Use is the same,same people in the home,same habits, and I cannot explain it,it worked fine at approximately 2-275 galon tankfulls per year.The Bock seems to fire up more frequently than it used to,any ideas?


  • Jon_blaney
    Jon_blaney Member Posts: 317
    I have the same tank and use half that amount of oil. I think you may be leaking hot water somewhere. Tank keeps firing to heat replacement water.
  • Jamie Hall
    Jamie Hall Member Posts: 23,415
    I agree. Most likely problem is a small leak or a drippy faucet somewhere. It is really surprising how much water that can use up in a day. Keep in mind that a single drop every 10 seconds is two gallons a day; a steady drip will be a bathtub full...

    Also check potential cross connections, or leaks through mixing valves allowing hot water to drawn along with the cold.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 16,885
    Also, when was the last time you had that unit serviced? And did they actually open it up and clean it?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    Or your oil tank is leaking, or you didn't get the amount of oil you paid for, or someone stole it.

    There was an error rendering this rich post.

  • OuterCapeOilguy
    OuterCapeOilguy Member Posts: 46
    I would emphasize proper service of these units. My (late) parents had one of these, and it was not properly cleaned for several years. (In addition, the burner was a Wayne, I think a model MSR-imho a piece of junk). The result was a very expensive puffback. The single flue passage through these heaters don't take long to clog with soot if they are left for too long; in the meantime, the soot greatly inhibits heat transfer. They ended up replacing the Bock with a Weil-McLain Gold with an indirect water heater and a cold-start control-a much better solution for both the heat and hot water.
  • Jon_blaney
    Jon_blaney Member Posts: 317
    I would think that poor performance would result in longer run times not more frequent burns as the questioner states.
    HVACNUT Member Posts: 5,857
    Slab leak?
    And you're using a single pass water heater for space heat?
  • ChrisJ
    ChrisJ Member Posts: 15,767
    edited August 2023
    Usually bad rings or valve stem seals cause excessive oil usage. Sometimes bad PCV.

    Ok, that aside...

    Could a small leak actually raise oil usage a noticeable amount? Wouldn't you notice it if it was large enough to cause the burner to run more than normal?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Jon_blaney
    Jon_blaney Member Posts: 317
    Could be an internal leak which goes to steam and up the chimney like what happens on a boiler.

    Maybe you have to see how often it is actually running. Sit with it one morning while you are having your coffee and see.

    Have you shut off all the heating valves?
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,323
    Hi @Huckelbuck , Another thought is to turn off the water supply to the heater after putting a water pressure gauge on the tank's drain. If pressure falls off, you know there is a leak someplace, which could be a big part of the problem.

    Yours, Larry