Reno Part 73 - Range Hood & Make Up Air Vents

[@bengt_axle]

Given that it is unconditioned air, is it not simpler (and cheaper) to just open a window in the kitchen when running the exhaust?

[@TrytoCatch22]

Depends if there is an in-line filter or not. If there is no filter, than yes, it the same as opening a window

[@DerekNheiley]

Another good question. Yes, this is essentially an automated window opener that never forgets. Especially if your exhaust has a timer built in. We will have a large air filter on all the mechanical air intakes into the house.

[@DerekNheiley]

@bengt_axle regarding a window being simpler and cheaper, there's one scenario that would be a concern. Let's say for example a guest forgets to open the window and it's -10c outside and it's the middle of the winter. You'll start pulling more air through the fresh air intake of your ERV, unbalacing that system and potentially freezing the core. Depending on the ERV, and what type of auxiliary pre-heater and temp sensors are setup, this might work for a while, but is not ideal as you'll still not meet the air requirements for the range hood exhaust. Also if anyone is taking a shower, the exhaust side of the ERV is severely outgunned in a tug of war against the range hood exhaust. So now your bathrooms aren't venting properly either.

[@baptistlion4060]

what about a dryer dumping air outside?

[@DerekNheiley]

that’s a good question! We’re changing over to a condensing heat pump dryer that doesn’t vent to the exterior at all. Another benefit of these units is that they run on 120v, and come as combo washer dryer units. The trade off is longer drying times.

[@baptistlion4060]

@@DerekNheiley Love it! Id like to get one for my new house but I doubt ill spend the money on it yet

[@flinch622]

I would never put an opening for make up air in the lower half of a wall - dust and debris are going to be a problem Stick it under eaves, or convenient high point. Worst case might be post & beam where ceiling or floor joists for the above story are simply not oriented to put a duct run in the ceiling given other building features? Go under the house, then turn up outdoors. Protect the duct with a chase, set rain louvers, and provide cladding to complement the house - siding, stucco, whatever. Then there are temperature concerns of winter: a heat exchanger at a minumum, and harsh places that find themselves to be honorary Canadians every January... install a preheater that regulates btu level when outside air temp goes below a certain threshold to set incoming air temp [and is inactivated near/above 50 degrees].

[@DerekNheiley]

In my case (a reno of 2x4 walls instead of 2x6 new build) I’m very limited on where I can run things without adding bulkheads and chase ways outside of walls. Our makeup air intake will be protected by a porch roof covering that area of the back of the house :). Also the first several feet of the duct slope to the exterior to prevent ingress of wet weather. I’m not aware of a residential erv/hrv or even pre-heater that can keep up with a large 600+ cfm exhaust range hood. I believe it’s accepted best practice to not condition make up air due to it’s short lived and localized passage through a house for a short time frame - only when the range hood is active.