HRV/Air exchanger connections with forced air duct system and interlock
Hello, I recently bought a townhouse (2 stories + basement). There is a furnace and a heat pump (HVAC system) and there are ducts everywhere except the basement.
I want to improve ventilation using an HRV. I had several ventilation specialists come in and they all seem to think that putting in separate ductwork is not a consideration in my house. They all seem to suggest attaching the HRV unit to the furnace. I am ok with this idea except I am getting conflicting information that I was hoping you could help me with:
1 – Some say that they will exhaust stale air from the RETURN of the forced air duct system and supply the fresh air through the SUPPLY of the forced air duct system. is this ok? If not, why is it bad to supply fresh air to the supply of the forced air duct system (as opposed to supplying the fresh air to the return of the forced air duct system, as suggested by some other ventilation specialists).
2 – My furnace has an ECM motor… but I still hear the fan well enough through my 2 return ducts on floors 1 and 2. I dont want the furnace fan to work 24h a day so I can hear it constantly!! My main concern is basement ventilation in the first place… so I was wondering… Is it acceptable to have the HRV work say 20 min per hour (with the furnace fan) but then completely turn OFF and I can have quiet in the house for the next 40 minutes? Or does the HRV need to absolutely work 24/7 constantly?
3 – One contractor suggested that an interlock is NOT absolutely necessary between HRV fans and furnace fan. He says if he supplies to supply of furnace and exhausts from return of furnace then when the fan of the furnace is OFF, the fresh air will passively go through the ducts anyways… not as efficiently but that it will still get to desired locations. He says the new Fantech models are powerful enough with 175cfm or so, for this kind of design. And this way I can have a my furnace go on and off periodically as it is working now, without any HRV in the house – which is how i prefer it. Does this approach make sense?
4 – Between Lifebreath, Fantech or Minotair, is there one that you would suggest more for Montreal, QUEBEC weather?
Sorry in advance if this question has already been asked, but I couldnt find the answer to this question anywhere on the internet (especially the first question!). I really appreciate your input on this! Thank you in advance.
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