I live in Zone 4A – 2 story colonial. 

I’ve been doing a lot of work on sealing the home and improving insulation. I removed the R-30 BIF (blown-in-fiberglass) in my unconditioned attic and replaced it with R-60 cellulose (what a difference in temperature for the upstairs!). I also put a vapor barrier in the crawlspace and sealed up the foundation vents. Dedicated dehumidifier running in the crawlspace (40% crawlspace RH right now vs 65% a year ago, upstairs RH % is better but not ideal, 2nd story still about 50% vs 40% for the downstairs) 

The next challenge is fresh air. I have 2 air handlers, one in the unconditioned attic (not my choice, builders) and the other in the crawlspace. I want to do a ERV, but I don’t know where upstairs I can put it. What I would like to do:

– Panasonic Intelli-Balance 100 ERV or a Broan ERVS-100S. 
– Cut a hole in the ceiling upstairs and mount it between the studs in the ceiling (attic floor). The reason for this is easy maintenance / change the settings/filters.
– Cover the ERV in the cellulose on the attic side. 
– Run the ducts from the ERV just above the studs but buried in the cellulose. 
– Have 3 dedicated exhaust ducts, 2x for the upstairs bathroom, and one for the center foyer area (for the stairs). Each one should be about 15 to 20CFM for exhaust. The locations for the exhaust ducts are very close to the physical location of the ERV. 

– Connect the supply air to the air handler in the attic on the return side plenium box. (Positive pressure?)

Is it safe to do it this way without worrying about moisture building up because it’s mounted, more or less, in the floor of the attic but in the ceiling of the upstairs? 

Also, is this unit too loud? The master bedroom closet is close to the access hatch for the attic, which is not far from the locations I want to place the dedicated exhaust ducts. It’s also fairly close to the air handler return plenum box.