Pressure issue with through-wall ERV?

[amanda_maine]

I am close to purchasing a through-wall ERV like Lunos e2 or Vents-US Twinfresh for a small house with a wood stove. The wood stove (Quadra Fire Millenium 2100) will have outdoor air intake.
As I understand it, through-wall ERVs work with *alternating* air flow and pressure - e.g., 20 seconds negative pressure (exhaust), 20 seconds neutral, 20 seconds positive pressure (intake)
I'm concerned that in the positive pressure cycle, it could push wood smoke/particulates further into the room.
Does anyone have experience pairing a through-wall (alternating pressure) ERV with their wood stove?
What issues did you have -- And how did you address them?

 

[kennyp2339]

How tight is the space? like is it closed cell spray foam or is it conventional with some air sealing?

 

[EbS-P]

Two thoughts. I have no experience with them. 30 cfm for 70 seconds will make no noticeable change in house pressure. Bathroom fans run. Several minutes at 80 cfm. So my main concern bringing the smoke smell. I’d want it in the side of the house facing prevailing winter wind maybe. Seems to me a device that works for 500 sq ft is small. I’d try with out one unless code calls for one. A traditional ERV with adjustable in/out put would be my choice. It I see where this would be considerably cheaper.

What exhausting appliances do you have and what is the cfm rating? So if the dryer, bathroom fan and kitchen hood are on what is the worst case outflow that you might need to make up?

 

[begreen]

I'm not fond of these reversing setups. Look at different HRV systems that keep a continuous positive pressure in the room. The Panasonic Intelli-Balance 200 is an example. The units have user-adjustable settings for equalizing pressure and do not reverse.

 

[amanda_maine]

How tight is the space? like is it closed cell spray foam or is it conventional with some air sealing?

Good question - It's 3" exterior EPS and 2x6 framing with dense-pack cellulose and new Marvin windows...My builder wants to believe it will be well-airsealed; we will see!

 

[amanda_maine]

Two thoughts. I have no experience with them. 30 cfm for 70 seconds will make no noticeable change in house pressure. Bathroom fans run. Several minutes at 80 cfm. So my main concern bringing the smoke smell. I’d want it in the side of the house facing prevailing winter wind maybe. Seems to me a device that works for 500 sq ft is small. I’d try with out one unless code calls for one. A traditional ERV with adjustable in/out put would be my choice. It I see where this would be considerably cheaper.

What exhausting appliances do you have and what is the cfm rating? So if the dryer, bathroom fan and kitchen hood are on what is the worst case outflow that you might need to make up?

Re: Traditional ERV being cheaper - What $$$ are you estimating for a traditional ERV (equipment and/or install)? Just curious; i haven't gotten quotes yet.
For the Vents-US units, they're $750 per unit, I'd get two, plus paying someone for a few hours work to install, and then an electrician I think...

Re: Exhausting appliances - No major appliances in house; it's actually a yoga studio with a teeny kitchen (single electric burner & toaster oven but no stove) and a shower...No washer/dryer.

The space with the stove will be *closed* when the space has people (1-5 people) & the wood stove is running. It's a 350 square foot space with peaked ceiling...heat pump on one wall and wood stove on other side...wondering if it's okay to get just put a *single* reversible ERV in the space, or to use a pair to balance pressure when the door is closed.

Then to your point, maybe I don't need an ERV at all in the part of the house with a "kitchen" because there are few major appliances...I could run the bath fan when cooking.

 

[EbS-P]

Making more sense now. Those units are more than I was thinking. It’s a small space. I would be getting an outside air kit for the stove. That’s a small space. Well insulated walls how about floor and ceiling. And what stove just to bring it all together. I think a traditional adjustable erv would be better in a yoga studio. It would give you more flexibility to fine tune. Otherwise it’s just going to be opening a window. It could be a sauna with a big enough stove.