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Opinions on vent damper for boiler

MaxMercy Member Posts: 498
My gas boiler at work has a motorized damper in the stack, and it's about 20 years old and has worked perfectly (Effikal). It's properly wired with two safeties and the boiler won't fire unless it's wide open.

I've been thinking about adding a similar damper to my oil fired boiler at home to try to squeeze a bit more efficiency now that oil cost more than milk..

It seems the only brand of damper I can find are Field Controls which used to be Effikal but reviews show them to be troublesome recently, so I have a couple of questions. Are vent dampers worth the time/trouble/cost and if so, is there a reliable brand anyone would recommend? Is there a difference between applications for gas and oil? Any insight appreciated.


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,600
    edited November 2022
    In the 1970s and 80s there were several manufacturers that tried to cash in on the idea, many were installed on oil boilers and they did save on fuel cost. However they are problematic and were not widely accepted by the service community and were placed on the permanently open position in order to solve a no heat call.

    I was one of those service call companies back in the day. There was even a company called Energy Stack Vent in the Philadelphia area that sub contracted me to install them. I got $25.00 for each simple install on a gas heater. But he always called me on the difficult ones where his other installers would mess up and needed someone to fix it. His product was all hype and overpriced cased on the fuel usage. the same damper would be sold for $250.00 to some one with a moderate fuel bill, and over $500. For those with higher fuel bills.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Steamhead
    Steamhead Member Posts: 16,734
    @MaxMercy , the Field/Effikal GVD and similar dampers are for atmospheric gas units ONLY.

    Field does make a damper for oil-fired units, here:


    which incorporates a blocked-flue sensor that mounts in the smoke pipe instead of on the draft regulator. It also waits a couple minutes before closing, to keep odors from forming.

    I like dampers. In addition to keeping chimney draft from cooling the boiler down when the burner is off, they also reduce infiltration of cold air into the building when the burner is off.

    If you're not an experienced contractor, do not attempt to retrofit a damper yourself.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • SuperTech
    SuperTech Member Posts: 2,126
    I honestly don't think they are worth it. My boss has me leave every vent damper we see open all the time because he knows that the damper will inevitably cause a no heat call for the customer.  And the vent damper necessitates the usage of a L8148E aquastat that is bound to fail at a solder joint for the vent damper.

    When you factor in the inevitable service calls will you really see any return on the investment? There's a good reason why oil boilers aren't sold with them installed....
  • Dave Carpentier
    Dave Carpentier Member Posts: 579
    Where does most of the loss originate anyhow ?
    With a hot boiler, if you had no air able to get into the boiler or the barometric damper, I suppose some convection within the stack could occur. Cold air falling down and hot rising.
    But is the main problem the actual air thats able to get into the system and 'feed' the convection right at the boiler ? How much air gets into the burner area thru the non-rotating fan cage/combustion chamber ? How much room air creeps into the barometric damper, stealing room air and aiding in the convection (since it's so close to the hot boiler) ?
    30+ yrs in telecom outside plant.
    Currently in building maintenance.