I'm in the midst of a remodel of an older home, and leaning towards the Lunos E2 HRVs for simplicity and space. I've heard from one person with direct experience, and was curious if there is anyone else who can share their experiences? If you also have experiences with conventional ERV's, that would be good to know, as well.

I have a single pair of Lunos E2 ventilating the basement. The 2-bit binary controls (2 paddle switches) to set the speed is something only a digital engineer could love, but 475 has an overpriced encoded rotary switch solution that makes it more intuitive for the rest of the population.

It comes in a couple of lengths, and even with the thickness an ICF wall I had to build a little insulated wall console extend 3" to the interior to accommodate the long version. As a retrofit on a framed wall you'll almost certainly be using the shorter one.

They're nice and quiet, seem to work like a charm.

Thanks, Dana! Someone else must have some experiences with these to share, though I am leaning towards them. I think with the insulated wall you helped me spec out, I will only be like 1/4" shy on the depth. I am curious, if having the brick veneer on the outside (and no closed cell sheet) is an efficiency issue for the longer unit.

Ideally the ceramic heat exchanger core would be completely within the insulation. In both the short and long versions interior side houses the fan and filter, so it's something like 2.5-3" inches from the conditioned space side of the interior cap to where the core begins, and the core is another 3-4". A not fully dimensioned drawing can be found on page 2 here, but it appears the short version's core is less than half the length:

https://foursevenfive.com/wp-content/uploads/2016/08/e2_installation_instructions.pdf

Depending on your insulation stack up may want to do what I did, and build a shallow wall console sufficiently deep to accommodate the fan & filter, electrical box for the controls & switches etc, so that the exterior end of the core doesn't extend beyond your insulation. If need be, fitting some high density batt around the tube to fill the built-up console can ensure that the interior side end of the core is fully within the insulation layer. My installation was in a 2" + 2" ICF on one end, and on a poured concrete foundation with 3" of interior side polyiso on the other. Rather than having the core within the concrete portion of the ICF I made the console something like 4" deep filled with rock wool. The console on the other end was an inch shallower.

If you remember, I had the vapor barrier on the back side of the brick veneer, about 3.5" from the inside of the foundation wall. We had talked about furring out the wall with 3" polyiso and another 3/4" furring strip. I'm actually considering using just a 2x3 furring strip on the outside of the wall for rigidity and some extra U factor reduction with 3/4" more insulation in the stud bay. In either event, we'd be talking from the interior drywall, 7.75-8.5" of insulation before getting to the vapor barrier and brick. Based on the numbers you provided above, it sounds like that would put the 5.5-7" you were mentioning within the insulation cavity by at least 3/4-1.5". Am I reading this right? If so, then there must be about 5-6.5" between the core and the exterior wall face.

I think we're on the same page, and I'm pretty sure your insulation layers are thick enough for the long versions, but to review:

If you look at the dimensions on p. 2 of the Lunos e2 installation document the minimum assembled-installed length inside the wall of the longer unit is 11.8". Minimum assembled length inside the wall of the shorter unit is 8".

The tube can be any length you like, and you can position the unit anywhere you like within the tube that you like. The fan & filter assemblies add up to a couple of inches (not dimensioned in the drawing) and the filter assembly is basically in the interior wallboard hole, the fan can be further away or snug up to the filter. There is also some space (not adjustable, and not dimensioned in the drawing) between the fan and core. I suspect there is always going to be at least 2.5" or 3" from the interior paint side of the wallboard and the interior side end of the core. The core is 3.5-4" long making the exterior side of the core at least 6-7" from the conditioned space interior.

I should have measured it when I had it out on the bench. I find it unconscionable that they don't provide a more fully dimensioned mechanical drawing for their product.

interior cap/grille | wallboard/filter + fan, ~2" | space (1/2") | core ~3.5-4" | space (1/2" min) | exterior siding (brick, in your case) | exterior grille

The dimensions in the drawing are everything between the interior & exterior grilles/caps, not including the grilles themselves. The interior cap extends 1.4" into the room, the exterior grille extends 0.7" into the great outdoors.

Ok, thanks Dana! Yeah, I think it will work, and it's good to know you can position the core anywhere in the length of the tube. I assume it doesn't slide 'down' the tube with vibration/use, given they say to have the tube pointing slightly downward to the outside, for any condensation.

I'm pretty confident I'll fur over the polyiso with the 2x3, as the 1.5" thick strip would allow me to use 18 cu in receptacle boxes, without having to cut the foam. I still have to figure out how run the wiring and stay > 1.25" from the surface of the furring strip. I saw these: http://www.viperstrap.com/ which would work well to attach the wiring to the surface of the foam, if I am able to confirm they'll meet code. Where I need to run some half-hot plugs with 14-3, I'd likely have to either add another 1/4" furring to the wall, cut the foam to route the wire, or use EMT (but then I would probably have to ground the EMT).

Just a comment on assembly: In theory 2x3 furring works just fine, but in practice 2x3s are a LOT more dog-legged & twisted than 1x4s, and also more prone to splitting. The up-charge for the wider furring is worth it, IMHO.