The RenewAire system is sized per ASHRAE 62-1999, residential air exchange of .35 air changes per hour, or 8 air changes per day. You can find an operation sheet for the PTL @ www.renewaire.com
, downloads, residential, controls, PTL. A chart shows a starting point of ventilation based on the square footage x 8 foot ceiling height with a run time percentage for each model. For 2250 square feet with 8 foot ceilings, the run time for an EV130 is 85%, cycling hourly.
Actual run time will vary by tightness of house, number of occupants, lifestyle (number and frequency of pollutant generating activities). Outside weather conditions should have little effect on run time percentage. I run my system @ 50% year round, when the windows are shut.
The ERV tempers humidity and temperature extremes of the ventilation air year round. It is not a substitute for heating or A/C; it does not dehumidify the house in summer (it does reject some of the incoming summer humidity content, when the net humidity is greater outside than inside). It will lower humidity of the house in winter, or whenever the net humidity outside is lower than inside.
It will ventilate the house in an energy efficient manner all year long. Based on this information, choose a setting and manage the amount of run time to achieve your best IAQ.