How unbalanced can an HRV / ERV be commissioned? - GreenBuildingAdvisor

How unbalanced can an HRV / ERV be commissioned? JMRtbay | Posted in Energy Efficiency and Durability on February 14, 2026 08:54am Just curious if there are any first hand accounts of how unbalanced an HRV/ ERV can be made to run to create positive pressure?  My owner built home is coming along in CZ7 (NW Ontario). Had a blower door test done yesterday and obtained incredible results of 0.2ACH50 which equals only 85 CFM of leakage in my 35,000 cu ft home. We had a Fantech ATMO 300cfm ERV roughed in with dedicated ducting, along with a 2.5 ton Mitsubishi Zuba ducted heat pump. My hvac installer mentioned they typically try to commission the ERV to be slightly positive. Just curious if there are any first hand accounts of how much positive pressure an ERV can generate. We have no other exhaust only appliances except a range hood which will only run on low and we will need to crack a window if the woodstove is running.  Answer GBA Detail Library A collection of one thousand construction details organized by climate and house part Search and download construction details Join the leading community of building science experts Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field. Start free trial Related Questions Running ERV Unbalanced Sizing an HRV/ERV System Recommended ERV that can be unbalanced to slightly over pressurize house? Do I need an HRV/ERV for a house built in 1947? Replies Behind_the_W...