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Decommission oil fired forced hot water

maxfactor Member Posts: 2
Hello heating experts,
Wow, what a lot of great advice on this site. Love it. I have a question:
I have installed heat pumps in my home to replace forced water oil fired for heating (with woodstove backup/supplement). I will leave the oil based boiler in place for a while but am looking for advice for whats best to do with it for long term shutdown. Should I drain the copper pipes? What about the oil in the tank and lines running to the boiler. Should these be drained or treated (like I do with small engine gasoline in the winter)?


  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    I would not drain the pipes. I would, however, make sure that the system is clean, and that there is an adequate level of anti-corrosion additive in the water. Further, some types of pumps have seals which tend to harden and take a set if they aren't used, and are much happier if they are run now and then. Likewise valves can get difficult if not exercised. For which reason I would plan on running the system up to temperature once a month or so.

    As to the oil, by far your best bet is to fill the tank and keep it that way. There are stabilizers for diesel fuel which also work well for heating oil -- it's the same stuff -- and I would use those. If at all possible use real fuel oil, not biodiesel or blends. If all you can get is a fuel oil/biofuel blend (quite likely, these days), then you should also use a diesel biocide additive. If all you can get is straight biodiesel, then you absolutely have to use a diesel biocide additive as well as an anti0corrosion and water control additive.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,828
    Are you eventually going to have the woodstove and oil boiler removed? If not, then Jamie has the best advice. Exercise the system once a month up to full temperature during the heating season. Exercise the pumps with cold water (no burner operation required) during the summer months. The full fuel tank is to reduce the chance of condensation forming inside the tank. This is recommended if you plan on using a full tank next season. If that fuel is going to be there for 5 years or more then I might opt for keeping the tank below 1/4 tank full. At a future date 10+ years from now, when you wish to recommission the oil heat system, a new tank may be in order at that time. The tank location and the tank condition will also determine whether to leave it full or not over the dormant time.

    A 5 gallon can of Deisel, from the filling station, should be enough to exercise the system each month. This of course depends upon your intentions for future use of the system. You may not like the comfort level of a heat pump in January and February. That is when you will determine if the oil boiler will operate more or less over the next decade.

    You may want to add radiant floor hear in the future. Nice to already have a boiler in place to add that option to your comfort options.

    My 2 cents

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • maxfactor
    maxfactor Member Posts: 2
    Thank you Ed and Jamie. Good advice that makes sense. I'll look into fuel stabilizer for diesel. I certainly don't want a full tank of oil that may never get used. At some point the tank will be removed from the cellar before it leaks. The wood stove will probably remain in place.
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,541
    Have you gone through a winter with heat pumps yet? I would before burning the bridge
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • Steamhead
    Steamhead Member Posts: 16,832

    Have you gone through a winter with heat pumps yet? I would before burning the bridge

    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Cokomo
    Cokomo Member Posts: 16
    We had 5 single Mits hyper heat units installed in ranch home in early Jan. . Also had Rheem hybrid water heater installed @ same time . Made the 32 yr old Peerless oil fired boiler cold start ( w help from this site) and am still using the oil heat today . The plan was to test a winter season w both mini splits and fhw boiler.  We now know we never want to be wo oil heat . The minis are nice for some heat but will be used mainly for ac . Going to see how the boiler handles being off all summer and if it leaks, buy a System 2000 boiler. Would have already but finding a dealer who doesn’t sell oil has been more than difficult . Long live oil heat !