MaintainlyHow often should you clean your HRV / air exchanger filters?
Clean HRV / air exchanger filters every 3 months. The commonly recommended range is every 3 months. Clogged HRV filters cut fresh-air flow and make the system work harder.
A heat recovery ventilator continuously swaps stale indoor air for fresh outdoor air while keeping most of the heat. It is common in airtight modern homes, and because it runs constantly its filters load steadily rather than seasonally. Natural Resources Canada says to clean or replace them every one to three months.
Why does cleaning your HRV / air exchanger filters matter?
Clogged HRV filters cut fresh-air flow and make the system work harder.
What happens if you skip cleaning your HRV / air exchanger filters?
Blocked filters or hoods unbalance the supply and exhaust flows, which is worse than it sounds. Natural Resources Canada warns that a ventilator pulling out more air than it brings in puts the house under negative pressure, which can make carbon monoxide and other combustion gases spill back from a furnace, water heater or fireplace instead of leaving by the chimney. Airflow and heat recovery drop too, but the pressure imbalance is the real problem.
How do you do it?
- Disconnect the power. Turn the unit off and unplug it before opening it. Do not rely on a wall control alone.
- Open the front cover. Usually two clips or thumbscrews. The unit is typically in a basement, loft or laundry.
- Withdraw the filters. There is normally one on the supply side and one on the exhaust. It is easy to clean only one of them.
- Wash or replace as specified. Washable filters are vacuumed first, then washed with mild soap and water and dried completely before refitting. Some filters cannot be cleaned and must be replaced.
- Clean the core every six months. Follow the owner’s manual: methods differ between models, and some cores must not be soaked.
- Clear the exterior hoods. The intake and exhaust hoods and screens outside collect leaves, insects and lint, and in winter snow and frost.
What does it take?
How do you know cleaning your HRV / air exchanger filters is overdue?
- Windows fogging on the inside in cold weather when they did not before
- Stale or stuffy air despite the unit running
- The unit noticeably louder than it used to be
- Visible dust matting the filter media
What do people get wrong?
- Cleaning one filter and not the other
- Refitting filters while they are still damp
- Never removing the core
- Forgetting the outdoor intake hood, which can be the actual blockage
What changes how often you need to do it?
- Pollen season loads the supply filter quickly
- Nearby construction or a busy road shortens the interval
- Wildfire or bushfire smoke loads the supply filter very fast
When should you stop and call someone?
Natural Resources Canada recommends a general service once a year by a qualified contractor, which includes measuring the supply and exhaust airflows and confirming they are balanced, and checking the defrost system. Filters, hoods and core cleaning are a homeowner job.
Does this differ in the US, UK, Australia or Canada?
United States
HRVs are found mostly in tightly built newer homes in colder states. ERVs, which transfer moisture as well as heat, follow the same filter routine, but check the manual before washing an ERV core.
United Kingdom
The equivalent is MVHR, mechanical ventilation with heat recovery, fitted in airtight new homes. Ventilation in dwellings is covered by Approved Document F of the Building Regulations. Filters are usually replaceable cartridges with an interval stated by the manufacturer.
Australia
Whole-house heat recovery ventilation is much less common, since most homes ventilate by opening windows or rely on exhaust fans. Where fitted it is usually in high-performance builds. Bushfire smoke seasons load filters extremely fast and are the main reason to check early.
Canada
Natural Resources Canada’s schedule is filters and outside hoods every 1 to 3 months, the core and the condensate drain every 6 months, and a contractor service with a defrost check once a year. Winter is the critical season: clear snow and frost from the hoods. If you ever switch the HRV off, provide ventilation another way.
Frequently asked questions
Why does cleaning your HRV / air exchanger filters matter?
Clogged HRV filters cut fresh-air flow and make the system work harder.
What happens if you skip cleaning your HRV / air exchanger filters?
Blocked filters or hoods unbalance the supply and exhaust flows, which is worse than it sounds. Natural Resources Canada warns that a ventilator pulling out more air than it brings in puts the house under negative pressure, which can make carbon monoxide and other combustion gases spill back from a furnace, water heater or fireplace instead of leaving by the chimney. Airflow and heat recovery drop too, but the pressure imbalance is the real problem.
Does cleaning your HRV / air exchanger filters differ by country?
Canada: heat recovery ventilators (HRV / air exchangers) are standard in newer homes; clean the filters regularly. AU: uncommon outside high-performance builds, but where fitted bushfire smoke loads the filters very quickly.
How we put this together
The figures, intervals and legal points on this page were checked against the sources listed below. The default interval and accepted range are the ones Maintainly uses in its task library. Costs and times are typical ranges and vary by region and by home. Your own manufacturer's instructions come first, and gas, electrical and structural work belongs with a qualified professional. How we research and write.
Sources
- Heat Recovery Ventilators (booklet, revised February 2012), Natural Resources Canada. Checked 11 October 2026.
- How to maintain a heat recovery ventilator, Canada Mortgage and Housing Corporation. Checked 11 October 2026.
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