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Makeup air for an high-efficiency fireplace

sfortier | Posted in General Questions on

After reading this article and all the comments,, I’m now very concerned by the makeup air vent that was installed to my fireplace, a 4″ vent connected to the bottom right side that is wide opened (see picture). I thought the damper on the fireplace was basically closing/opening that vent but this is not the case at all and now hearing this could be a fire hazard, and a fireplace really needs only 15-25 CFM, I think I will disconnect it…

My new house will be very, very tight (still need to have the blower door test), I’m thinking of converting this vent as a hood range makeup air with a motorized damper and inline fan, controlled by a sensor on the range chimney. I know 4″ will not provide a lot of CFM but not intending to have a powerful hood range either. The fireplace is maybe 15 feet away from the hood range. Do you think this is a good idea? What about using the same makeup air vent for the dryer (I get I could not use both the dryer and range hood at the same time)? Maybe also add a switch nearby the fireplace to open the damper just to provide some makeup air when starting a fire instead of opening a window? Any expert opinions are welcome!

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  1. Expert Member


    Before disconnecting that air intake check both the manufacturer's instructions and the applicable parts of your building code. It may not be legal to do so.

  2. sfortier | | #2

    Malcolm, good questions:
    - air intake is not a requirement of our building code
    - the manufacturer installation document says the fresh air intake kit is optional (

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