Most HRVs in Ontario houses are installed, plugged in and never touched again. Some were never balanced. Some get switched off in November because “it was blowing cold air.” Then the owner wonders why the windows are dripping.
Here is what balancing is, why your inspector may want it tagged, and how to set and care for an HRV through a real winter.
An HRV brings fresh air in and sends stale air out. Balancing means measuring both airflows and adjusting them until they match the design. In and out, equal.
Unbalanced, the HRV either pushes the house positive, which can drive moisture into the walls, or pulls it negative, which brings in cold drafts and can pull air back down a chimney.
Many Ontario municipalities want the HRV installed, balanced and tagged before occupancy. Your installer measures and records the airflows. The design airflows come from your ventilation summary (RMVDS).
Your installer balances to numbers. Those numbers are on the ventilation design. No design, nothing to balance to.
Winter is when a tight house needs fresh air most. Continuous low speed is the normal setting.
Showers, cooking, a house full of people. Then back to low.
Many HRV and window makers suggest lower indoor humidity on very cold days. Wet windows mean it is too high.
Snow and frost can block the intake and exhaust. Check them after a storm.
Check them every couple of months. Dirty filters choke the airflow.
At least once a year, following the maker’s instructions.
Turned off or on its lowest setting all winter is the most common cause.
Showers, cooking, laundry, plants and people all add moisture.
An unbalanced HRV may not be moving the air it should.
An undersized unit cannot keep up. That is a design question. See HRV selection.
A good HRV install starts with a ventilation design: how much air the house needs, where the supplies and exhausts go, and how it ties into the heating. That design goes into the ventilation summary (RMVDS) for your permit and gives your installer the numbers to balance to. See HRV and ERV design and HRV vs ERV.
Building or renovating? We do the ventilation design and the RMVDS with your heat loss, so the installer has numbers to balance to.
Get Free Quote →Measuring the fresh air coming in and the stale air going out, and adjusting until they match the design airflows. An unbalanced HRV pushes or pulls on the house, which wastes energy and can cause drafts, condensation or backdrafting.
Many Ontario municipalities want the HRV installed, balanced and tagged before occupancy. Ask your building department what they want to see.
No. Winter is when a tight house needs fresh air most. Run it continuously at its normal low speed and use high speed for showers, cooking or a full house.
Lower as it gets colder outside, or your windows will sweat. Many HRV and window makers suggest dropping indoor humidity on very cold days. Follow your unit’s guide and watch the windows: condensation means too much moisture or not enough ventilation.
Check the filters every couple of months and clean the core at least once a year, following the maker’s instructions. Check the outside hoods after snowstorms. A blocked intake hood is a common winter problem.
Usually indoor humidity is too high for the outdoor temperature, the HRV is set too low or turned off, or it was never balanced. Sometimes the windows themselves are cold. Start with the settings and the balance.
Send your drawings. We do the heat loss, the ventilation design and the RMVDS together, with design airflows your installer can balance to.