Mechanical Ventilation Required
Low electricity consumption and very high energy-recovery efficiency are features to look for.
A Zehnder energy-recovery ventilator (ERV) will bring fresh air into the house and remove stale air. As the two airstreams pass each other in an ERV, the conditioned outgoing air tempers the incoming air, reducing the temperature differential the minisplit system must overcome and transferring moisture to the cooler airstream. The ComfoAir 350 ERV, which has an adjustable ventilation rate that ranges from 29 cfm to 218 cfm, was chosen because it met the ProHOME’s ventilation needs at 50% capacity, leaving plenty of capacity to boost the ventilation rate when it’s needed, such as when people are showering.
The Passive House-certified Zehnder units are often seen in higher-end builds because of their extremely low electricity consumption and very high energy-recovery efficiency. Although the material costs are at the high end of the range for ventilation equipment, the proprietary ducts, called ComfoTubes, reduce installation time. The 3-in.-o.d. flexible ducts fit inside 2×4 walls and snap easily into diffuser boxes with a simple clip system. The ceiling-mounted supply diffusers can be dialed to the proper flow rate during commissioning.