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Recommendation for compact ERV for bonus space

jadziedzic | Posted in Energy Efficiency and Durability on

I’m searching for a compact ERV to use in an above-garage bonus space of approximately 500 square feet (CZ5).  The space has a dedicated mini split, is insulated on all sides (roof slope, ceiling, below floor, gable end), and has a small bathroom which I’d like to exhaust via the ERV.  Since the space is fairly air-tight I don’t want to use an exhaust-only solution for the bathroom.  I have a small closet area I could use to house the ERV and would prefer something around 18″ hwd with top ports, CFM output minimum 40-ish maximum 60-ish.

Via some Google time I’ve found the Lifebreath “30 ERV” and the Greentek “ERV SS 3.80 FSD” as possible options.  Anyone used either of these units, or have any recommendations for other brands in that size range?

FYI, an HVAC designer suggested the Panasonic FV-04VE1 but that can’t be installed in the bathroom according to the specs, plus it really isn’t rated to be used in our climate zone, so that’s off the table.  Running an intake/exhaust duct back to the main living space ERV is a 50-foot or so run through an unconditioned attic space so that’s also off the table.  (The duct could be buried in the blown-in cellulose (R-60) but it would only have 7 or 8 inches of insulation above the top of the duct.)

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  1. DennisWood | | #1

    I would do the 50 ft run back to existing ERV for simplicity.

    We did a large commercial project where all ducting for the 2nd floor was done in unconditioned attic space (zone 7A) and it is not a big issue if you first ensure zero air leaks, then properly insulate the pipe. In our case, we were talking about 4000 sq/ft serviced by these ducts (many with acoustic linings as a film studio and isolated tenant spaces were involved) with a total square footage of about 9000 sq/ft. That building was a net zero'ish target envelope and among other innovations (furred air space interior wall structure) was considerably more efficient than most people's homes here.

    All second floor ducting was in the unconditioned attic space with approx R80 of cellulose. The ducts were taped, then wrapped with faced pipe insulation, then buried in cellulose. Is there room for more cellulose in the area that you would run your ducting?

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