Recirculating range hood?
sbabcock61
| Posted in General Questions on
If I’m building an air tight home, should I be looking to vent my kitchen exhaust via the range hood directly to the outside or should I get a recirculating range hood and let the HRV system take care of excess humidity, etc
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
If you search for "makeup air", you'll probably find some good articles and discussions. Martin has written several, and there are extended discussions following.
Also, read BSI-070 from the Building Science Corp's website. The title and quote that start the article give you the overall direction. Additionally, farther down in the article, he specifically addresses providing makeup air for kitchen range hoods, with two different approaches depending on the air flow rating for the hood.
IMO: you'll get better results with less money if you stick with something less than 200cfm. Whatever you do, don't put in gas kitchen appliances. Look at induction first.
Thanks for your direction on this - I'll check out the links
As it turns out we are planning on Induction for stove top
Steve,
Here is the link to the article that Andrew was talking about: Makeup Air for Range Hoods.
If you have an ERV/HRV would an exhaust fan pull extra air thru the ERV?
Eric,
No.
ERVs and HRVs are designed to provide balanced ventilation: Air in = air out.
Every manufacturer of an ERV or HRV, as far as I know, explicitly states that these units are not makeup air systems.
As Martin says, ERV/HRV is not designed to provide makeup air, and it would be a bad idea of count on it for that. On the other hand, the answer to the question "would an exhaust fan pull extra air through the ERV" is yes, to some extent. The percentage that gets pulled through the ERV vs. the leaks in the envelope depends on the particular ERV and on how tight the house is. My gut feel for that is that you'd have to be in an extremely tight house to get the percentage that comes through the ERV above 10%, but I could be wrong about that.
The Ultimate Air Recoupaerator has an optional pressure control that adjusts flow based on measured pressure to maintain neutral pressure across the envelope. In theory that would inherently boost intake airflow to provide makeup air except that it can only do that up to 60 CFM, and it has a very slow controller on it. But the time it adapted to the range hood being on, you be done with cooking. So those are the reasons why they don't recommend it for that purpose.
I would support the low CFM exhaust fan; directly vented as opposed to recirculation, and especially if you like to cook a lot. I base this on my client feedback, and personal experience with lingering cooking oders. However, it's good to note that we live in Portland where the weather is pretty mild in the winter and our heat loss for direct exhaust doesn't seem to be all that bad. It's much less than anticipated. I'm sure you are aware that its best to vent out of the side as opposed to through the roof, whenever possible.
We faced the range hood situation recently in our house, very tight construction in cold climate (zone 6a). We have an electric range and are light duty cooks. We really didn't want to put another big hole in the wall and deal with potential draft/condensation/heat-loss issues in the winter.
We purchased a basic low CFM Broan recirculating hood and started to plan the mount, but decided we didn't really like the look and realized a range hood might not be necessary. We returned it and didn't install a range hood at all. The wiring is there if we change our minds.
After 6 months in the house, we are happy with this decision...cooking odors/grease/humidity are not an issue for us (keep in mind electric range and light duty cooking). Vented kitchen exhaust wasn't required under the version of Energy Star we did.
This may not be an option or desired option for you, but I'd at least just consider a low CFM recirculating hood, particularly for electric/induction range and if you are light duty cooks.