Air Filters & MERV Ratings Explained

Your air filter does two jobs: it protects your equipment from dust, and it helps clean the air you breathe. Choose well and change it on schedule, and you've handled the single highest-payback maintenance task there is. Choose a "maximum" filter your system can't handle, and you can quietly sabotage your comfort and your bill. Here's how to get it right.

What MERV actually measures

MERV (Minimum Efficiency Reporting Value) is a 1–16 scale of how much a filter captures. Higher MERV traps smaller particles. But there's a catch most stores won't mention: a higher-MERV filter is denser, so it's harder to pull air through. That matters more than the headline number.

The MERV sweet spot for most homes

The right choice is the highest MERV your specific system can handle while still moving air freely — not the biggest number on the box.

Why "maximum" can backfire

A too-dense filter raises static pressure — the resistance your blower fights. The results show up as: weaker airflow to your rooms, a higher chance of a frozen indoor coil, more strain and wear on the blower, and higher energy bills. If you've ever "upgraded" your filter and then noticed weaker cooling, this is why. It's closely tied to your ductwork and airflow.

How often to change it here

Central Texas is dusty and the cooling season is long, so filters clog faster than the package claims. As a rule:

• 1-inch filters: every 30–60 days (shorter in peak summer).
• 4–5-inch media filters: every several months up to a year.
• The reliable test: check monthly; if it looks gray, swap it.

A clean filter is the first thing to check whenever cooling weakens — see why your AC isn't cooling.

Filters and air quality

A good filter changed on schedule is the foundation of indoor air quality. It's also the cheapest. Before considering an add-on purifier, make sure the basic filtration is dialed in — it often resolves the concern on its own.

How MLD helps with filters

We'll tell you the right MERV for your equipment — not just sell you the priciest filter. During any visit, our technicians check your filter, airflow, and static pressure, and explain what your system is actually designed for. It's a small thing, but getting it right protects the big, expensive parts. We've advised Leander-area homeowners this way since 2009 (license TACLA37761C).

What to do next

• Rooms uneven or airflow weak? Read Ductwork & Airflow Basics.
• Want the big picture? See Indoor Air Quality 101.
• Want filters handled for you? Ask about our maintenance plans, or request a visit.

Call 512-528-4258 and we'll match the right filter to your system.