Filter Replacement in Apex, NC

The standard answer is every 90 days. The real answer for Triangle homeowners is more often than that — usually every 30 to 60 days, depending on your household.

The 90-day guideline comes from filter manufacturers testing in controlled conditions. Those conditions don't account for North Carolina's pollen, Triangle humidity, pet hair, or the fact that your HVAC system runs 8-10 months out of the year here instead of the 5-6 months assumed in national averages. More runtime means more air moving through the filter, which means faster accumulation.

Here's a practical guide based on what we actually see in Triangle homes.

Every 30 Days: Change Monthly If You Have...

- Pets (dogs and cats both — dogs shed more volume, cats produce more dander per pound)
- Anyone in the home with asthma or allergies
- A home near construction (half of Apex and Holly Springs had active construction within a mile in 2024)
- A home backing up to wooded areas where pollen, mold spores, and organic debris are heavy
- A household of 4+ people

Every 45-60 Days: Change Bi-Monthly If You Have...

- No pets, 1-2 occupants
- A newer home with good sealing and insulation
- Moderate allergy sensitivity

Every 90 Days: The Rare Case

- Vacation home that sits empty most of the time
- No pets, no allergies, minimal system runtime

During peak pollen season — roughly mid-March through late May in the Triangle — every home should move to monthly changes regardless of household factors. Wake County pollen counts regularly exceed 1,500 grains per cubic meter during April, which is classified as "very high." Your filter will be visibly yellow-green within weeks.

What Happens When You Wait Too Long

A clogged filter doesn't just mean dirtier air. It creates a chain reaction of problems in your HVAC system.

Restricted airflow forces the blower motor to work harder. Amp draw goes up, the motor runs hotter, and its lifespan shortens. Blower motors cost $400-700 to replace.

Reduced airflow across the evaporator coil causes the coil to get too cold. In cooling mode, this leads to ice forming on the coil. A frozen coil blocks airflow completely, and the system shuts down. The ice can also damage the coil fins.

In heating mode, restricted airflow causes the heat exchanger or heat strips to overheat. The high-limit safety switch trips and shuts the system down to prevent a fire. If this happens repeatedly, the high-limit switch can fail, which removes your last line of defense against a cracked heat exchanger.

Higher energy bills are the most immediate impact. A dirty filter can increase energy consumption by 5-15%, according to the Department of Energy. On a $200/month Duke Energy bill where half is HVAC, that's $5-15 wasted per month. Not dramatic, but it adds up over a year — and it's the easiest savings available to any homeowner.

Choosing the Right Filter

MERV rating is the standard measurement for filter effectiveness. Higher MERV = smaller particles captured = more restriction to airflow. The trick is finding the rating that captures what matters without choking your system.

MERV 1-4: Basic fiberglass filters. Catches large dust and debris. Protects the equipment but does almost nothing for air quality. These are the cheap blue filters from the hardware store.

MERV 8: The sweet spot for most Triangle homes. Captures dust, pollen, mold spores, and pet dander. Provides good air quality improvement without significant airflow restriction. Most residential systems are designed for this range.

MERV 11-13: Higher filtration. Captures smaller particles including some bacteria and smoke particles. Good for allergy sufferers. But check your system first — some older air handlers can't pull air through MERV 13 filters without strain. Our techs can test static pressure to tell you the highest MERV rating your system can handle.

MERV 16+/HEPA: Do not put these in a standard residential HVAC system unless it was specifically designed for them. The airflow restriction will damage your equipment. If you need HEPA-level filtration, you need a separate whole-home air purifier installed in the ductwork.

A note on "allergy" and "premium" branded filters: look at the MERV rating, not the marketing. A $20 "allergen defense" filter at MERV 11 does the same job as any other MERV 11 filter at half the price.

The Right Size Matters

Filters come in nominal sizes (what's printed on the package) and actual sizes (what the filter actually measures). A filter labeled 20x25x1 might actually measure 19.5 x 24.5 x 0.75. This is normal. What matters is that the filter fits snugly in the filter slot without gaps around the edges. Air always takes the path of least resistance — a gap around a filter means unfiltered air bypassing the filter entirely.

If you're not sure what size you need, pull out the current filter and read the size printed on its frame.

Filter Replacement with Our Maintenance Plans

Filter replacement is included with our maintenance plans. We bring the correct filter to each visit and swap it out as part of the service. For homeowners who prefer a one-time visit, we're happy to schedule a standalone filter replacement appointment. We'll also check the filter slot for proper sizing and sealing while we're there — a surprising number of homes in the Triangle have filter slots that don't seal properly, which defeats the purpose of even the best filter.

If you're changing your own filters between visits, buy in bulk. A 4-pack of MERV 8 filters costs less per unit and means you always have one on hand when it's time to swap.