Exhaust air from the ERV does not need insulation?
Jim Sweazey| Posted inGeneral Questionson
Zone 6B
I read in one of the articles on or linked to GBA that the outside air to a ERV should be insulated to prevent condensation. It seems to imply that the exhaust air from the ERV does not need insulation. I had planned on insulating both but if this one doesn’t need it, the job that much easier.
Thanks
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Jim,
If you want to maintain your warranty, follow the manufacturer's instructions. On the Panasonic Intelli Balance, for example, the installation drawing calls out insulated ducts on supply and return.
I would insulate it. Whether it's a condensation problem depends on how good your HRV is at extracting heat from the exhaust, making that stream cold, and depends on how high your interior humidity is, but regardless of whether there's a condensation risk, there's heat loss. It's closer to outdoor air temperature than indoor temperature, so leaving it uninsulated a significant heat loss that can easily be reduced.
Thanks guys, will do!
For energy reasons alone, it makes sense to insulate it. In whatever mode it's operating in, the air temperature in the exhaust is going to be such that heat transfer from the pipe to the indoor air will be detrimental a large proportion of the time (and never better than neutral). The wall penetration is also a thermal bridge to the outdoors.
Minimizing supply/return duct length is also beneficial.