HRV options for main bedroom

I was looking into this a few months ago for my bedroom. Ended up buying a Vent Axia Pozidry pro with heater. It supplies filtered air from the attic to the upstairs landing. Went with F7 filters as I live beside a busy main road. It didn't help Co2 levels all that much in my bedroom but PM 2.5 dropped through the floor. I did check out those other ones and rang around but the installers price didn't pursuade me, I installed the Pozidry myself. One other advantage, the kitchen smells used to come up the stairs, with positive pressure now they stay downstairs. It also ensures some air movement in the bathroom etc. Knocking a new hole in my wall just didn't appeal to me for 1 room.....hope this helps!

I looked at the Mitsubishi Lossnay VL-100(E)U5-E but the cost of install - new hole being required didn't appeal in the end. It does heat recovery though.
How are you going to deal with the HRV ducting to the outside in the attic? Knock two holes in the gable end wall? You'll need two holes - extract and intake with a specified distance between them. Also insulating the intake pipe whilst providing a condensation drain from the unit.
The only other thing is blocking the vents - any air tightness testing done? It will be very hard to balance the system between the rooms in a leaky house....any thoughts of flow / calcs with that in mind?
Best of luck with the project though - particularly given the attic is converted....

It's easy enough, steps as follows:
Install unit in attic - I got F7 filters which cover down to PM 2.5, they are a bit lose though so hacked some clips to ensure they gripped on ok. The unit comes with a heater, 500w, not sure how that will eat electricity but I have a monitor and under normal operation it uses very little as far as I can tell, also it cuts out when the temp in attic goes over a set level to avoid pumping really warm air into the landing.
There's a flexible plastic stretchy duct to link to between the unit and the vent. You cut a hole in the landing to the dimensions - measure twice, cut once, I nearly cut one twice as large as needed! Then fit the vent, attach the duct to it and you're almost ready. I've no plugs in the attic so I ran a wire and plug down a hole to the landing where a socket is located so anyone can unplug it if it's drawing in BBQ smoke or gives any problems.
I installed rubber under the feet of the unit to dampen noise, you can still hear a slight vibration at times when its running. It has several speeds which you can choose. The denser the filter, the harder it has to work - my F7 filters in particular.
Results - it is mostly used by landlords to keep damp pushed out of the bathroom, which is does a good job at. It relies on the gaps under the doors for the bedrooms and the fact you've a vent in the room to channel the air out through. It didn't make a significant difference to CO2 but PM 2.5 in particular was cut by and large. So, not the magic bullet I was after but an improvement all the same and it's running all the time. It keep kitchen smells downstairs which was a bonus, they always ended up in my room after cooking.
They are designed for self install. Any single room units I was quoted for were @ 1K and upwards.
I think I'd prefer a unit that fed my room directly next time around, a future upgrade perhaps. The Pozidry has an adapter that can feed two branches if you want to feed a different room which is an option. Filters should last a few years. Had some insulation smells when the filter was a bit lose, otherwise it creating positive pressure upstairs and for a few hundred euro, a useful improvement. It's like a big hairdryer!