Best location for ERV supply outlets
We are building a new construction house in Des Moines, IA (climate zone 5). The goal is a pretty tight house (< 1ACH50), and we are using variable speed furnace & AC and a Lennox ERV with dedicated ducts.
The mechanical contractors will begin the install next week, and I’m looking for suggestions on the best locations to place the fresh air supply outlets, especially in the bedrooms. We have 3 smaller bedrooms (approx 12′ x 12′) which will be kids rooms, and I’m concerned about the possibility of cold drafts during the winter.
I’m curious around recommendations for where to place the outlets for maximum comfort.
As always, thanks for all the info and advice!
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Hi Burke,
Perhaps you’ve read this already, but if not it would be worth a look: https://www.greenbuildingadvisor.com/article/a-new-way-to-duct-hrvs
The pertinent part is relative to exhausting air from the bedrooms and providing fresh air to the living space to mitigate that cooling concern you mention.
The standard answer is to avoid putting it right the head of a bed. I tried to abide by that when I did my house (not as simple as it might sound, because bed placement can change), but in retrospect it didn't matter at all. I have to get up on a ladder to even have a chance at feeling the air coming out of any of the supplies. That's just anecdotal, and it obviously depends on the air velocity and air temperature in your application.
You also want to minimize short cycling of fresh air to the exhaust, which reduces your effective air change change rate (or increases the rate that you must ventilate to achieve the same equivalent air quality).
Diffuser position throw and angle would all affect this, but at the low flow rate, location will probably be the biggest factor.
Thanks for the great answers.
I hadn't ever thought of exhausing from the bedrooms, so that's something to consider.
We are looking at needing around 100 CFM, so after that is divided up between all the places we are supplying fresh air, I think the actual CRM in each bedroom will be pretty small.
The point about diffuser positioning in relation to the furnace & ac duct returns is an interesting point, and something I'll chat with our mechanical contractor about.