Range Hood
jesse_m
| Posted in Building Code Questions on
We purchased a home that was built in 2020(started in 2019) and the range hood above the gas stove has a CFM of 420. I have been told that based on when the building took place that there should have been an air intake installed with a damper to allow makeup air to come into the house. Nothing has been installed that I am aware of. Should there have been and are there any options to install after the initial build has been completed? I contacted the HVAC contractor that was involved with the build process, but I am not sure what he will recommend or be willing to to do help.
we are located in climate zone 4A near Charlotte, NC.
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Replies
Look in the cabinet over the vent or in the exhaust piping for a small thing with wires sticking into the pipe. If so, you definitely may have makeup air.
The makeup air can be far from the exhaust hood. In my house the intake is in a soffit, the duct goes through the attic, and the damper is in the attic, and it dumps into a less used part of the house through a ceiling vent.
Do you know what every exterior vent & damper is for?
They are fairly easy to install. The most difficult part is getting the wiring that sends the signal from the vent telling the damper the vent is on and the damper should open, but with smarthome relays, there are other ways to send the signal.
I do not see anything connected to the hood other than the powerline and exhaust duct. I really think they missed installing it because I think I have accounted for each vent coming out of our house and know what they are for.
Makeup air requirements are pretty new, and like anything new in codes and construction, it takes a while for them to become common practice. The 400 cfm threshold is somewhat arbitrary; in a tight house (≤1.0ACH50) every range hood should have makeup air, and in a drafty house (say over 7ACH50 or so) a 1200 cfm hood probably wouldn't need makeup air. They can be added after the fact, with some repair work likely to be required.