Zehnder ComfoAir Q Guts

A review of the new Zehnder ComfoAir Q ERV explained in detail - inside and out. * note and correction, balanced ventilation happens via Fan Speed Modulation.

[@kahuswanson9696]

Your description about the bypass seems incorrect to me. The bypass is only for bypassing the heat exchanger (this is often for efficiency reasons and when you don't want to heat exchange), and nothing to do with whether the unit runs balanced or not....

[@PassiveHouseCody]

I may have misspoke in the video and I flew threw the details several years back. I surmise you're correct in finding an error on how the bypass works. It is indeed for efficiency in preserving the desired indoor set temp. Thank you.

[@sofiegundersen8343]

Very useful video! We've installed the q350 ourselves, but struggle to fit it through the trusses as the display screen comes out (about 10mm short). Do you know if we'd save a few mm taking away the display? Or will the control board (which I assume is behind it) stand out too?

[@PassiveHouseCody]

You can pop the display face off. Be careful, it's meant to replace if needed. Service manual here to reference first www.zehnderamerica.com/wp-content/uploads/2022/05/ComfoAir_Q_Service_Zehnder-America_EN_2022.05.18.pdf

[@jessicaeasto]

I have a ComfoAir Q (and a very airtight home; we moved in in August), and I was wondering if / how the machine can tell if the window is open or if we are using the kitchen range hood. Are you saying that the machine automatically knows this somehow? People warned us that using a kitchen fan for too long, for example, could depressurize our house. We've heard conflicting things about what the ERV can and can't make up for. Would you be able to explain this a bit more? Also, our installer did not use those black sleeves on the cold ductwork. We did notice condensation this winter, and someone is coming to fix it soon. Are those sleeves supposed to go through the *entire* wall assembly? I have no idea how they are going to retrofit these, if that's the case (and obviously moisture is a huge concern).

[@PassiveHouseCody]

Once the Q is commissioned correctly it prefers to stay balanced. So if a door opens or closes; or a small exhaust influences the balance, the Q series speeds up or slows down fans. Here is an excellent resource on good technique on installation. www.zehnderamerica.com/wp-content/uploads/2019/09/Zehnder-Installation-Manual-9.20.19.pdf

[@jessicaeasto]

@@PassiveHouseCody Thanks. This document mentions an already insulated ComfoPipe, but in your video, it shows a black sleeve. Are these different components?

[@PassiveHouseCody]

@@jessicaeasto In an advanced wall assembly there are several layers. In the video you see black comfopipe going through a wall hole that has been taped with ProClima Contiga Solido Exo from exterior Air Barrier To interior Drywall forming a water proof penetration for the comfopipe to rest in. Good eyes!

[@mujkocka]

what kind of size of home could it serve?

[@PassiveHouseCody]

More dependent on Bathroom to Bedroom ratio but ~ 2500-5000 SQFT it's the largest before jumping into commercial Ventacity units. Thank you.

[@PassiveHouseCody]

Typically up to about 3400 sf.

[@DiederikAms]

I have the 930 DeLuxe model and the core got frosted from the low outside air temperature. It also made the ventilator on that side run noisily. Any thoughts on that?

[@PassiveHouseCody]

Check to make sure the preheater is chosen under the P menu and that there are no preheater errors. If the preheater was supposed to turn on and didn't there would be an error like A7

[@DiederikAms]

@@PassiveHouseCody Thanks. At first I was afraid though mine didn’t have a preheater, but I checked the manual and it has. In previous maintenance I was stupid enough to be a careless when tidying the wires, which obstructed the flap. Perhaps that was it. Hopefully it is fixed now. Settings P51 and P72 in order now. Many thanks for putting me on the right track!