Westminster: filter selection and what actually matters

Westminster homeowners ask us about filters constantly. Should I get a 1-inch or a 4-inch? MERV 8 or MERV 13? Pleated or fiberglass? The honest answer is that filter choice matters less than how often you change it, but a few details are worth knowing.

MERV ratings explained simply

MERV stands for Minimum Efficiency Reporting Value. Higher numbers catch smaller particles.

• MERV 6-8: catches dust and pet hair. Fine for most homes.
• MERV 11-13: catches finer dust, mold spores, and most allergens.
• MERV 16+: hospital-grade. Almost always too restrictive for residential systems.

The catch with higher MERV ratings is restriction. A MERV 13 filter pulls more air pressure than a MERV 8, which means your blower motor works harder, and on some older Westminster systems can actually reduce airflow enough to hurt cooling.

What we recommend

For most Westminster homes:

• A MERV 8-11 1-inch pleated filter changed every 60-90 days is the right answer for most systems
• If you have allergies, step up to MERV 11-13 and change more often
• If you have a high-static system or a 4-inch filter slot, use a 4-inch MERV 11 or 13 filter changed every 6-9 months

Cheap fiberglass filters do nothing useful. Don’t bother. And don’t buy filters once a year and forget them — a clogged filter is the single most common cause of comfort complaints we get on service calls. More on what’s involved in AC repair when filters cause issues.