How to Change Your Air Filter: Complete Guide

A dirty air filter is the #1 cause of HVAC problems. The good news? Changing it is a simple, 5-minute DIY task that saves hundreds in repairs.

Why Air Filters Matter

A clogged filter:

• Reduces efficiency by 15-25%
• Forces your system to work harder
• Increases energy bills
• Can trigger system shutdowns
• Reduces indoor air quality
• Shortens equipment life

Bottom line: Change it regularly and avoid 90% of problems.

Step 1: Find Your Filter

Location: Usually in one of these places:

• Main air return (bedroom closet, hallway)
• Attic near air handler
• Basement near furnace
• Garage near HVAC unit

Look for: A large rectangular vent with air flowing inward

Step 2: Check the Current Size

The filter frame is marked with dimensions: 16x25x1 or 20x25x4

Write down the three numbers. You'll need them to buy a replacement.

Step 3: Buy the Right Filter

MERV Rating Explained

MERV Rating	Filters	Best For
6-8	Basic fiberglass	Minimal filtration
11-13	Pleated (standard)	Most homes RECOMMENDED
14-16	HEPA-like	Allergies, pets
17-20	True HEPA	Medical needs

For most Bay Area homes: MERV 11 or 13 is perfect.

If you have allergies or pets: MERV 15-16

Warning: Don't go above MERV 16 unless your HVAC is rated for it (reduces airflow).

Brand Recommendations

• Filterbuy: Great quality, affordable
• Honeywell: Reliable standard
• Furnace Fresh: Premium pleated
• Amazon Basics: Budget-friendly

Cost: $15-50 per filter (depends on size and MERV)

Step 4: Turn Off Your System

1. Find your thermostat
2. Set to OFF (not heat or cool)
3. Wait 5 minutes for air to settle

This prevents dust from flying around when you open the filter cover.

Step 5: Remove the Old Filter

1. Open the return air vent or access cover
2. Note which direction the arrow points (airflow direction)
3. Carefully slide out the old filter
4. Don't shake it (releases dust)

Step 6: Install the New Filter

1. Check the arrow on new filter points in same direction as old one
2. Slide new filter into frame
3. Make sure it fits snugly (no gaps on edges)
4. Close the access cover

Step 7: Turn System Back On

1. Return thermostat to HEAT or COOL
2. Set desired temperature
3. Listen for smooth startup (no rattling)

Replacement Schedule

Standard home: Every 90 days (3 months) Homes with pets: Every 60 days (2 months) Allergy sufferers: Every 30 days (1 month) New construction/heavy dust: Every 30 days

Pro tip: Set phone reminder on purchase date + 90 days

When to Replace Early

Replace filter immediately if:

• Visibly clogged or dark gray
• System making whistling sounds
• Weak airflow from vents
• Energy bill spiked
• New pet in home

Common Mistakes to Avoid

❌ Wrong direction: Check the arrow! Backwards = no filtration ❌ Wrong size: Measure twice, buy once ❌ Too high MERV: Can restrict airflow (only if system rated for it) ❌ Running without filter: Never! You'll damage the system ❌ Not replacing: "It looks okay" = still filtering all dust/allergens

Storage Tip

Keep 2-3 spare filters on hand:

• Always ready to change
• Prevents forgetting
• Stock up when on sale

Cost: $15-30 in spare filters vs $500+ repair = great ROI

Air Quality Benefits

Regular filter changes: ✓ Reduce dust on furniture by 30% ✓ Improve allergy symptoms ✓ Reduce pet dander ✓ Better smell in home ✓ Fewer respiratory issues

Questions?

Call us for filter recommendations or if you're uncomfortable changing it yourself.

Schedule Filter Service | Call (925) 578-3293