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Run Bathroom Vent as Makeup Air When Gas Dryer Runs...?

Greetings all and thank you, long time admirer of the site!

I'm a homeowner and finishing my basement. The gas dryer will be in the bathroom. My plumber rightly said the gas dryer needs makeup air while it runs now that it will be in a smaller space.

I will install a bathroom fan vented to the outside.

Stands to reason that a simple solution would be for the bathroom fan to run while the gas dryer runs. Is anyone aware of the best way or control to automate this?

It is a small bathroom, so I'll most likely get a moderate CFM fan. Do I need to consider the CFM in terms of the amount of makeup air for the gas dryer, though? If so what is the calculation to consider?

Many thanks for reading and considering my post and thank you!


  • ratio
    ratio Member Posts: 3,543
    Bathroom fans are exhaust fans, they don't bring air in. I think you're looking for a fan in a can, but IDK about interlocking it with a residential dryer.
  • motoguy128
    motoguy128 Member Posts: 394
    Running the bath exhaust would make it worse.  

    Cutting return grills into the Bathroom door or a wall that passes into the larger basement space would be adequate.  Unless it’s a tight spray foam insulated home. Then you  would will need ironically, to allow free air into the room.  
    JUGHNE Member Posts: 10,898
    Yes, both are exhausting units, the dryer more so.
    You could put a louvered door on the bathroom like for a furnace room.......would be a little different.
    Running the exhaust fan usually creates enough "white noise" to cover up private sounds that might originate there.

    My much used half bath has a fairly loud exhaust fan on motion sensor for this very reason. It is located centrally in the house next to the offices.
  • EnergyAdjacent
    EnergyAdjacent Member Posts: 2
    Thank you all for the responses. And yes I was all mixed up with what I posted, as the bath fan competes with the dryer, clearly.

    So far a louvered door is the leader in the clubhouse.

    What if I create a discrete passive vent in a wall between the bathroom and a room next to it. This could allow more air than a louvered door, and I could place it to the dryer. Any positives from that or does it net the same as the door?
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,137
    edited August 2020
    Hi @EnergyAdjacent , I think you might want to check local codes before proceeding. It seems any gas burning appliances in a bathroom may be in question. :* This link may help: https://www.thebuildingcodeforum.com/forum/threads/gas-dryer-in-bathroom.10954/

    Yours, Larry
  • MikeL_2
    MikeL_2 Member Posts: 470
    Gas dryers, just like furnaces, boilers, and other fossil fueled equipment, require combustion air, not make up air.
    HVACNUT Member Posts: 5,452
    Permits and codes are optional?
  • hot_rod
    hot_rod Member Posts: 20,725
    Those fans you see in RV ceilings can push or pull air depending on the settings.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • kcopp
    kcopp Member Posts: 4,301
    Install an electric Clothes' dryer.