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Make-up Air

I'm looking to add make-up air intentionally instead of letting it suck through the cracks. Is this a good idea? I already have a hard time getting the humidity up even with a whole house fan powered humidifier.


    HVACNUT Member Posts: 5,841
    An ERV would work, or if you have central air conditioning or a warm air furnace, an Aprilaire 8126X Ventilation Control System will bring in filtered air (through the existing return duct) to put the envelope under a slight positive pressure. It can be regulated by temperature and humidity.
  • Jolly Bodger
    Jolly Bodger Member Posts: 209
    What is "make up air" to you? Are you talking about replacing air exhausted from bathroom fans and kitchen hoods, or the air used by burners, or just the infiltration/exfiltration going through the envelope?
  • motoguy128
    motoguy128 Member Posts: 393
    edited January 2020
    He probably talking about air leaks from stack effect. Pulling in air into a controlled filtered location can reduce the negative pressure somewhat. More important with atmospheric equipment.

    I have a 6” constant makeup air duct into my downstairs air handler and a 6” dampered inlet in the boiler room that open with a heat call.

    I did this instead of an elaborate radon mitigation system. Levels in basement were creeping over 8-10 in the winter. With this system it’s under 4, averages 2.5. Levels are <0.5 on the 1st floor.