HVAC Filters 101: Types, MERV Ratings & Replacement Schedule

Breathe easy—literally. The air in your home or business passes through your HVAC filter dozens of times a day, trapping dust, pollen, and even things you can’t see. But not all filters work the same way. Miss a replacement, and your system could be working overtime—costing you comfort, money, and peace of mind.

At General Heating & Air, we know filter talk can sound like a different language. But whether you’re dealing with allergies, pets, or just want that “fresh air” feel, understanding your options is key. Here’s how to choose, change, and maintain your HVAC filters—no guesswork required.

Why Filter Quality Matters 🏠

Imagine your lungs trying to breathe through a scarf—now picture your HVAC system doing the same with a clogged or low-grade filter. The filter is your first defense against airborne particles, mold spores, and pollutants. According to the EPA, indoor air can be up to five times more polluted than outdoor air. That means the right filter isn’t just about comfort—it’s about keeping your air healthy.

Poor-quality or old filters can cause:

• Higher energy bills (your system works harder)
• More dust settling on surfaces
• Worsening allergies or asthma symptoms
• Unexpected breakdowns (emergency hvac calls aren’t fun at 2 a.m.)

Quality matters. And so does knowing when it’s time to swap out the old for the new.

Types of HVAC Filters

The world of HVAC filters isn’t one-size-fits-all. Let’s break down the main types you’ll find in homes and businesses:

Fiberglass Filters

Think of these as the “basic white bread” of filters. They’re cheap, disposable, and catch large dust particles. But their thin, webby design misses smaller irritants—stuff like pollen, pet dander, or mold spores. If your system is older or you’re on a tight budget, these work in a pinch. Just don’t expect miracles for air quality.

Pleated Filters

Imagine folding a paper fan—more surface area means more particles get trapped. Pleated filters (usually made of polyester or cotton) catch smaller dust, pollen, and some bacteria. They last longer than fiberglass and are a solid choice for most homes. The higher the “pleat count,” the better the performance.

HEPA Filters

HEPA (High-Efficiency Particulate Air) filters are the heavyweights. They trap at least 99.97% of particles as small as 0.3 microns—the gold standard for allergy or asthma sufferers. These are found in hospitals, labs, and some high-end residential systems. Not all HVAC setups can handle HEPA filters, though, so check your owner’s manual or ask a technician.

Washable & Electrostatic Filters

Some filters can be washed and reused. Electrostatic versions use a static charge to pull in particles. They can save money over time, but require careful cleaning—otherwise, trapped bacteria or mold could be released back into your air.

Technician Tip: Always check what kind of filter your system is designed for. Using the wrong type can block airflow and damage your equipment.

What Is a MERV Rating? 📊

MERV stands for Minimum Efficiency Reporting Value. It’s a scale—from 1 to 16—that rates how well a filter captures particles. The higher the number, the finer the filtration.

• MERV 1-4: Basic protection; mostly large particles. Suitable for older systems or minimal needs.
• MERV 5-8: Better for homes and many businesses; traps dust, pollen, and mold spores.
• MERV 9-12: Great for allergy sufferers; captures smaller particles like pet dander and fine dust.
• MERV 13-16: Superior filtration; captures bacteria, smoke, and even some viruses. Recommended by the EPA and many public health agencies for improved indoor air quality (IAQ Testing near you can confirm your needs).

Important: Not every system can handle a MERV 13+ filter. Too dense, and your equipment might struggle. Always check the manufacturer’s recommendations.

How Often to Replace Your HVAC Filter? ⏳

Changing your filter is one of the easiest ways to keep your air fresh and your system running smoothly. But how often should you do it?

• Fiberglass filters: Every 30 days
• Pleated filters: Every 60–90 days
• HEPA filters: Every 6–12 months (or as directed)
• Washable filters: Clean monthly

But these are just averages. Your real schedule depends on:

• Pets: More fur = more filter changes
• Allergies/asthma: Change more often for sensitive individuals
• Construction or renovation: Dusty work means quicker clogging
• Heavy system use: Hot summers or cold winters? Check monthly

Technician Tip: Hold your filter up to the light. If you can’t see through it, it’s replacement time.

Special Considerations for Allergies and Pets 🐾

Allergies and pets change the air game. Pet hair and dander can clog filters fast. Likewise, pollen and dust can trigger sneezing fits, especially during seasonal changes.

For allergy and asthma relief:

• Use a filter rated MERV 11–13 (as high as your system allows)
• Consider regular IAQ Testing near you, especially if symptoms worsen
• Upgrade to pleated or HEPA filters if your system supports them
• Change filters at least every 30–60 days during peak allergy seasons

EPA guidance recommends higher MERV-rated filters for households with pets or allergy sufferers, but always confirm compatibility with your specific HVAC system.

Quick Safety Checklist

Before you go swapping filters or buying the highest-rated option, run through this:

• Turn off your HVAC system before changing the filter
• Check the filter’s size and airflow direction (look for arrows)
• Never run your system without a filter—even for a short time
• Dispose of dirty filters in a sealed bag, especially if you have allergies
• Always use manufacturer-recommended filters for best results

DIY or Call a Pro?

Most residential and light commercial filters are easy to change. But not always. Odd filter sizes? Hard-to-reach locations? If you’re unsure, call a licensed technician. General Heating & Air offers 24 hour emergency hvac service for those “something’s not right” moments.

DIY:

• Easy access
• Standard filter size
• No visible damage to housing or ductwork

Call a Pro:

• Unusual noises, airflow, or odors
• Hard-to-access filter slots (e.g., in attics or crawlspaces)
• System requires multiple or specialty filters
• Interest in IAQ Testing, advanced filtration, or air balancing

What Pros Do On Arrival

Here’s what happens when a General Heating & Air technician visits for filter service:

1. Inspect filter size, type, and fit
2. Check airflow and filter housing for leaks or damage
3. Test system operation before and after replacement
4. Advise on best filter type and replacement schedule for your needs
5. Offer tips for further improving air quality—like dehumidifiers, air scrubbers, or duct cleaning

We follow EPA and manufacturer guidelines for safety and performance. No shortcuts.

Prevention & Maintenance Tips

Filters are just one piece of the puzzle. For the cleanest air and smoothest system operation:

• Schedule regular HVAC maintenance (spring and fall are ideal)
• Keep supply and return vents clear of furniture and clutter
• Consider duct cleaning if you see visible dust or mold
• Use high-quality filters—and replace on schedule
• Ask about IAQ Testing near you if symptoms or odors persist

A little upkeep goes a long way. Think of it as brushing your system’s “teeth”—it keeps everything healthy and happy.

Costs & Time Factors

Filter prices range widely:

• Fiberglass: $3–$10 per filter
• Pleated: $10–$30 per filter
• HEPA: $40–$100+ (special order for many systems)
• Washable: $20–$80 (but reusable)

Time to change? For most systems, it’s a five-minute job. Hard-to-reach filters or commercial installations might take longer. Don’t forget—neglecting filter changes can cost hundreds in emergency hvac repairs down the road.

When It’s an Emergency

Sometimes, a clogged filter is just the start. Watch for these signs:

• Sudden loss of heating or cooling
• Strange odors (burning, musty, or “dusty” smells)
• Unusual noises from vents or equipment
• System won’t turn on, or cycles too often

In these cases, shut off your system and call General Heating & Air for 24 hour emergency hvac help. Safety first.

FAQ

Can I use a higher MERV filter than my system recommends?

Not always. Too dense a filter can restrict airflow and strain your equipment. Always check your owner’s manual or ask a technician before upgrading.

What if my filter looks clean, but it’s old?

Replace it anyway. Filters lose efficiency over time—even if they look okay. Follow the schedule for best results.

Do filters help with viruses or bacteria?

MERV 13+ filters can capture some airborne viruses and bacteria, but no filter makes your air 100% germ-free. For added protection, ask about air scrubbers or whole-home purification options.

How do I choose the right filter for my business?

Consider occupancy, number of pets (yes, office pets count), and IAQ Testing results. In high-traffic or medical settings, higher MERV ratings or specialty filters may be needed.

Local and Seasonal Considerations

Colder climates mean longer heating seasons—filters clog faster. In humid areas, mold and mildew can be a bigger threat. If you’re running your HVAC system almost nonstop (think heat waves or cold snaps), check your filter monthly.

Seasonal allergies? Change filters before spring and fall pollen peaks for max relief. Renovating? Expect double the dust—and double the filter changes.

Ready for cleaner, healthier air and a more efficient HVAC system? Call General Heating & Air now — or reach us anytime at  888-805-8278 .