Hi All, thanks in advance for any insight and suggestions!

Been reading and learning for years off this site with the fantastic articles and Q&As, and really appreciate the top-notch quality of content. Hopefully this is a solid first question! (House details and ERV model at the bottom of post)

I’m getting a brand new ERV for really really low cost (well below wholesale) from an HVAC contractor and good friend, and trying to figure out how best to duct it for my own house.
The trick is, how I prefer my bedroom sleeping temperature different than the rest of the house. Every ‘best practice’ I can find, either using entirely stand-alone ducts, or tied into central HVAC, they all assume the goal is the same temp 24/7 in all rooms. What are other people doing for this? I know I’m not the only one who prefers sleeping in a cooler bedroom, and the most stellar whole-house solution is only as good as the weakest link (like occupants leaving windows open).

Currently what is working best for me in winter (no ERV), is to block off the supply register, open the window, and close the hallway door… which allows me to keep the rest of the house set to 20-21C overnight, and during our mild winter the bedroom gets to 15-18C, with lots of fresh air. But tons of losses and doesn’t work all year.

Then the flip side, in the summer I’ll be running AC, so likely will end up using dampers to bias slightly more cool air to the bedroom, and want to keep windows closed to keep AC conditioned air in, and forest fire smoke out.

So in the winter heating season, one idea is to use the heat recovery loss, to help cool the air in the bedroom… eg: draw from central return plenum (after filter grille is a huge bonus), then supply the fresh air into a new dedicated supply in the bedroom. So the 20-30% loss of heat with the ERV, would actually work out quite well to provide slightly cooler air to the bedroom. (rough calc: ~20C indoor air temp, ~10C outside air temp, so 10C delta, 30% recovery loss of that is 7C, meaning 17C air would be supplied to the bedroom. Close to perfect!)
^ But in summer, that would backfire, and that eff. loss, would result in slightly warmer air to the bedroom, exact opposite of keeping that room colder. Though, summer temp delta is a lot less, so recovery loss is almost negligible? (~22C indoor, 18-26C outdoor overnight, bedroom ideally ~18C)
^^ One other option is to use the recirc mode in the summer, so it mixes the overnight bedroom CO2 in with the rest of the house, not using the ERV core or any outside air overnight, and run it through the core during the evenings/days on a schedule?

Borrowed a meter to test PPM levels, and overnight they regularly went 1200-1800ppm in the main bedroom 10x11x8′ (one or two adults + dog) if the window is closed, hallway door is closed, and heatpump supply register sealed off. They don’t exceed ~800-1000ppm if I keep the supply open with the undercut hall door as return path to mix in with the rest of the house, but then I overheat at night. Or if I lower the thermostat, the whole house and floors are chilly in the AM with quite a bit of thermal mass to re-heat in such a short time before leaving for work.

Vanee: V160E75RT — 60-90% Apparent Sensible Effectiveness, and quite oversized, so will be running at very low cfm, getting quite high % recovery
(https://www.vanee.ca/en/products/residential-air-exchangers/90-ai-series-erv-v160-75.html)

Using their most advanced wall controller, giving the best options to run it based on a schedule, indoor temperature/humidity, recirc, etc.
(https://www.vanee.ca/en/products/accessory/94-advanced-touchscreen-control.html)

**I’d love to avoid interlocking the ERV with the heatpump (as the new Fujitsu is working incredibly well set on auto for blower fan speed, and I’d hate to interfere with that

House info: (ask if I’ve missed any useful details)
– Climate zone ~4C, but getting more hot/cold extremes every year (Victoria, BC, Canada)
– 1000sqft single level rancher
– four skylights, four glass patio doors, blown-in cellulose 2×4 walls
– attic above, decently well insulated, super well ventilated
– crawlspace below, fully encapsulated with 3-4″ of 2# closed cell on the walls/rims, and dimple + 20mil on the floor, gravity draining towards a backup sump pump, etc
– haven’t done a recent blower door since a ton of work has been finished, starting point was 13.8ACH50, but that had very obvious giant envelope holes at that point, should be able to get 3-6ach easily, but might try aerobarrier to get tighter just for fun now that an ERV is already paid for.
– Fujitsu 24k central, with brand new properly sized ducts, 20×25″ filter grille with 5″ merv11 media, system is ducted and sized fantastic, runs super long compressor cycles at the lowest variable speed, etc (24RGLXM w/ AMUG24LMAS)
– heatpump is in the encapsulated crawlspace, so all duct air leakage and the heat off uninsulated metal ducts keeps it really stable around 18-20degC, with enough air changes/flow to have zero smells, fantastic stable humidity levels, and keep all the plumbing safe in winter.
– bath fans are both exhaust-only 50 and 100cfm, 250cfm range hood