ERV Fresh Air Intake location: southern vs northern side of home zone 4a?
Hi, I am in the south (Nashville area zone 4a) and am installing my ERV (Energy Recovery Ventilator) and wanted to know how significant is a southern vs northern fresh air ERV intake?
It seems to be a significant difference of temperature between the south and north sides of home most of the daytime, the south being hotter due to the sun exposure and the bldg siding is barn red metal ribbed metal and is a rectangular ranch shape with 80ft long x 14ft high walls.
It is easier for me to do a southern side installation, but I have a plan to do a northern side if that is the wisest approach.
The house does need an ERV, tight construction.
The ERV will be a standalone ductwork because I heat/cool with a mini-split and have no duct work.
Thank you.
-Mike
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
I'm assuming your largest energy load is cooling, so I'd place your ERV intake on the northern exposure if you can. ERV intake/exhaust are typically right at the wall plane, so intake temps right next to red steel (an 80 x 14 foot wall!) on a southern exposure will be pretty high on a sunny day.
Great. I will do a northern wall intake.
I'd also consider the exposure of the inlets - it's nice if you can put the inlet under an overhang for some additional weather protection.
Is the ductwork going through an attic? If so, how much longer will the ductwork be at one location vs the other for the selected ERV location? My ERV has a temperature sensor for "outside air" but it's located at the unit. With about 30' of flex duct running in the attic between the inlet and ERV, the reported temperature is often about 5F warmer during the late afternoons than what my weather station reports (duct heat gain in a hot attic). Not great in summertime but it's actually helpful in winter.
The bldg is a barn/house (think large ranch bldg with apartment on one end).
The ERV is going in the shop which is well insulated. All duct work is rigid and I will use flex connection points at the ERV. Everything will be isolated in a framed and airtight plywood sheathed box on the wall between shop and apartment. The rigid duct will have an R-6 sleeve over it nd I will use polyiso to insulate the box the duct runs in.
By placing the ERV on the northern side of the bldg, all lengths are about the same, with the exception of the fresh air duct from ERV to the house. It will go from about 5 ft to 25 ft.