How often should I check or change my furnace filter?
Check it monthly during regular use and replace or clean it when dirty, following the equipment and filter manufacturer instructions.
Urgency: low
What this means
Use the exact dimensions and install the airflow arrow in the direction shown on the equipment.
Safe checks
- Write the installation date
- inspect monthly
- compare against a new filter
- keep the access panel closed after replacement.
Stop and get help if
- Call HVAC service if filters become wet, collapse, load unusually fast, or airflow remains poor with the correct clean filter.
Which professional to call
Contact the matched licensed or qualified trade if safe checks do not resolve the issue.
Find the relevant tradeSource and method
This answer combines HomeSOS's structured triage with safety boundaries supported by a public source. It does not replace inspection.
Health Canada: Home safety and indoor air guidanceReviewed August 12, 2026