Yes, I am trying to avoid any ductwork at all.

If you situate the unit properly, the ducting can be very minimal. Because HRV's have a very low flow, you don't need the kind of big ducts associated with heating systems.

Other than a HRV in every closed off room, I don't think "no ducts" can provide good air quality and energy efficiency. Of course a guest room could crack a window open occasionally and you might come out ahead.

No duct, no air quality. You can't have it both ways.

Code does allow for bathroom fans only in certain residences, doesn't it?

Posted By cathsand on 05 May 2013 12:08 PM
Am I wrong, or is this Daikin system both HVAC and ERV? http://www.daikin.com/global_ac/products/residential/urusara_series/outline.html
I am building a SCIP home with three basic modules of space. Each module will have scip envelopes. The left module is two bedrooms with Jack & Jill baths and closets in between, with a total of about 720 sq feet. The right module is about 720 square feet of master bedroom & bath and spare bedroom/den and bath. The middle module is a big square with about 1280 sq feet of open space. It will contain my kitchen, eating area and living area. Could I not use the Urusara for heat/air and erv for the big middle module? And then perhaps use the Panasonic whisper comfort erv for the J&J bathroom fan and the master bedroom fan. The only room not connected in some way to ventilation would be the guest bedroom (where no one will sleep most nights).

What do y'all think?

Where are you building? How cold does it get?

I am building in middle Georgia. We hardly even got below freezing this past winter. The ERV is for fresh air, not heat recovery.

An ERV recovers energy, stabilizing the conditioned space. So if you have cooled the air, heated it, or modified the rH, an ERV will "recover" what you would have otherwise lost. We install Renewaire in new houses and old, usually as the sole bath fan. This includes my own recent remodel where the fan runs year-round.

That's what I was thinking of doing MA. Just run two bath fan ERV's, plus the Ururu Sarara in the main space. But the rooms aren't connected with ductwork. Would leaving the guest bedroom door open suffice?

We usually exhaust bath and fresh air bedrooms or closet connected thereto. It is all about volume and people loads when it comes to ventilation.

If I take a shower on a hot humid day, I'd prefer not to recover any of it. Not the heat, not the humidity, I just want it gone quickly. In the Winter, I'm interested in keeping the heat and usually the humidity.

How well would fresh air circulate in a tightly sealed house with a centrally mounted ERV, no regular ducting and through-wall transfer ducts in every closed off room - I don't know. I'd be interested in numbers.