Furnace Filters

Check the filter slot or existing filter for printed dimensions (length × width × thickness) and match those exact numbers; if unsure, measure the slot opening and consult your HVAC manual or a technician to confirm compatibility

MERV (Minimum Efficiency Reporting Value) measures particle-capturing efficiency on a scale typically from 1–16; for most homes, MERV 6–11 balances filtration and airflow, while higher MERV (12–16) captures finer particles but may reduce airflow unless your system is rated for it

Replacement frequency depends on filter type and conditions: inexpensive fiberglass every 1–3 months, higher-efficiency pleated filters every 3–6 months, and homes with pets or allergies may need more frequent changes; check the filter monthly for visible dirt

Pleated and higher-efficiency filters capture smaller particles (pollen, dust, some smoke, pet dander) more effectively than basic fiberglass filters, which can improve indoor air quality, but effectiveness depends on proper fit, correct MERV for your system, and regular replacement

If a filter's MERV is higher than the system's design supports, it can restrict airflow, potentially stressing the fan and reducing efficiency; consult your HVAC specifications and, when switching to a higher-MERV filter, monitor system performance and energy use

Washable filters can save money over time but generally have lower filtration efficiency than disposable pleated filters and may require frequent cleaning to avoid airflow issues; verify they meet your system's airflow and filtration needs before choosing them

Install the filter with the airflow arrow pointing toward the furnace/blower, confirm it fits snugly in the slot with no gaps around the frame, and use the correct thickness and dimensions to prevent bypass and maintain rated performance