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Black box on exhaust line

Does anyone know what this black box on top of my exhaust is? I can't seem to find any information on it. The boiler is an Ack-O-Matic. The box has a power vent on it. I would like to get this boiler up this week if possible, its for an out building on my property, so if it needs to be replaced that'll have to wait until the summer to do so. Here's a couple of pictures of the unit.


    EBEBRATT-Ed Member Posts: 11,996
    I would think the black box is a vent damper. Boiler needs to be cleaned
    JUGHNE Member Posts: 9,760
    If that fan is on the black box and runs when the boiler fires then I think it is a heat reclaim unit.
    Pulls heat out of the exhaust and contributes to condensation in the chimney.
    Possibly a novelty gadget from the 1970's or so to save energy.
    They were also available for wood burners also.

    Should be removed, IMO.
  • Big Ed_4
    Big Ed_4 Member Posts: 1,884
    It's a heat reclaimer , they pick up some of the heat from the exhaust before it goes up the chimney to heat the basement ... They were big back in the 70's . There was also a hydronic model that brought the heat back to the boiler .. You will not see them , they all blow apart :)
    I have enough experience to know , that I dont know it all
  • Jamie Hall
    Jamie Hall Member Posts: 18,931
    As they folks up there said -- it's a heat reclaimer. And you really don't want it on there. ;;You can safely remove it and just put in another section of stack pipe.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Tom78
    Tom78 Member Posts: 1
    Thanks everyone for the information. Do I need to put a new exhaust fan back on it or just a new section of vent pipe? The fan runs both with the unit when on and the switch will allow it to run by itself. Should the new vent pipe be before or after the draft hood?
    JUGHNE Member Posts: 9,760
    Remove the entire box and fan, unwire the fan.
    The pipe and draft hood above the black box is a critical length item, can you tell if it was cut off?
    It should be the first thing on the boiler exhaust collar. Add a length of pipe above the hood to reach the 90.

    Of course, all this is after you clean the boiler.
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,689
    That reclaimer is probably the main reason why your boiler looks like that. You may want to have the chimney inspected too.
    That device lowers stack temperature below the dew point and your chimney may have taken a lot of condensing abuse.