Changing your furnace or air handler filter on schedule is the single easiest thing a Salem homeowner can do to save energy, extend equipment life, and improve indoor air quality. A clogged filter forces the blower to work harder, reduces airflow enough to freeze AC coils in summer and trip safety limits on furnaces in winter, and sends more dust and allergens into your home. Most 1-inch filters need replacing every 60 to 90 days. Media filters every 6 to 12 months. Set a calendar reminder and actually do it.
Why This Is the Highest-Return HVAC Habit
I’ve been doing HVAC work in Salem since 2001. In all those years, the most common cause of “my system stopped working” calls is a filter that hasn’t been changed in a year or more.
A filter’s job is simple: it captures dust, pollen, pet dander, and larger particles before they reach the blower and coils. Clean filter, free airflow, system runs the way it was designed. Clogged filter, restricted airflow, system struggles.
The impact of a clogged filter on a typical HVAC system:
- 10 to 20% drop in efficiency — the blower works harder for less airflow
- Shorter equipment life — a blower motor fighting against a clogged filter wears out faster
- Worse indoor air quality — once a filter is saturated, particles bypass it and recirculate
- System shutdowns — clogged filters cause furnaces to overheat and ACs to freeze over
- Higher bills — less efficient operation, more runtime, more electricity
All for a part that costs the price of a pizza and takes two minutes to change.
How Often to Change It
The “every 90 days” guideline is a starting point. Real frequency depends on:
Filter type and depth
- 1-inch fiberglass or basic pleated filters — every 60 to 90 days
- 1-inch high-MERV pleated (MERV 11-13) — every 60 to 90 days
- 4-inch media filters (in a dedicated filter cabinet) — every 6 to 12 months
- 5-inch media filters — every 12 months
- HEPA bypass filters — follow manufacturer’s specific schedule
Household factors
- Pets — shortens the interval. Shedding dogs and cats fill filters faster.
- Allergies — if anyone in the household has allergies or asthma, change more often to maintain IAQ
- New construction or renovation — drywall dust clogs filters quickly
- Open-window season — pollen season in the Willamette Valley (spring through early fall) loads filters fast
- Smoke events — wildfire smoke summers saturate filters in weeks, not months
- Heavy system usage — peak heating or cooling season uses the filter more
Home factors
- Dusty environment — homes in rural Scio, Stayton, or Sublimity near unpaved roads get more airborne dust
- Older homes — leaky envelopes pull in more outside particulate
- Crawlspace-to-house leaks — pull crawlspace dust into the return air stream
A practical approach: set a 60-day calendar reminder. When the reminder comes, pull the filter and look at it. If it’s clearly loaded, replace it. If it still looks usable, check back in 30 days.
How to Check a Filter
Takes thirty seconds.
- Find the filter location (usually at the return air grille, or in a filter cabinet near the furnace or air handler)
- Slide the filter out (note the direction of the arrow so you reinstall correctly)
- Hold it up to a bright light
- If you can see light clearly through the pleats — still usable
- If light barely gets through, or the filter looks gray/brown — replace
If you’ve never changed your filter and you have no idea when it was last done, just replace it. The cost is minimal and you’ve removed any doubt.
What MERV Rating Means
MERV stands for Minimum Efficiency Reporting Value — the scale that rates how well a filter captures particles. Higher MERV catches smaller particles.
- MERV 1-4 — cheap fiberglass filters; catch large dust and lint only
- MERV 5-8 — standard pleated filters; catch pollen, dust, pet dander
- MERV 9-12 — higher-efficiency pleated; catch fine dust, mold spores, some smoke particles
- MERV 13+ — hospital-grade pleated; catches fine particulate, smoke, bacteria
For typical Salem homes, MERV 11 to 13 is the sweet spot — catches most of what matters for comfort and air quality without restricting airflow too much.
MERV ratings and your system
Higher MERV restricts airflow more. Your HVAC system has a limit to how much static pressure the blower can overcome. If you put an ultra-high-MERV filter in a system that wasn’t designed for one, you’ll:
- Reduce airflow below what the system needs
- Force the blower to work harder
- Shorten equipment life
- Possibly trigger safety shutdowns
Before you put a MERV 16 or HEPA filter in, verify your system can handle it. We check static pressure during tune-ups and can tell you what MERV your specific system supports.
Filter Materials and Tradeoffs
Fiberglass (MERV 1-4)
Cheapest. Terrible at catching anything small. Useful only for protecting the system, not improving air quality. Avoid unless you’re changing them very often.
Pleated (MERV 5-13)
The workhorse category. Better surface area than fiberglass, much better particle capture, still affordable. Most homes should be using a MERV 8 to 13 pleated filter.
HEPA (MERV 17-20)
True HEPA in a standard furnace filter slot isn’t possible — HEPA restricts airflow too much. HEPA can be used in a bypass configuration where a portion of return air is routed through a dedicated HEPA filter. Expensive and not necessary for most homes.
Washable/reusable
Electrostatic washable filters sound good but generally perform worse than disposable pleated filters. The environmental benefit is smaller than it seems — the water and soap used in cleaning offset the saved filter material.
Signs Your Filter Is Overdue
Beyond the visual check, pay attention to:
- Weaker airflow at supply registers than usual
- The system running longer than normal to reach setpoint
- Dust accumulating on furniture faster than usual
- Anyone in the house with allergies getting worse indoors
- A musty smell when the system starts
Any of these on an older filter is your cue.
Filter Sizes
Filters come in standard sizes, printed on the edge of the frame. Common residential sizes include 16×20, 16×25, 20×25, 14×20, 14×25, and 20×30. Measure the existing filter before buying replacements — systems installed in older homes in Woodburn, Stayton, or Independence sometimes have non-standard sizes that require custom ordering.
If your filter slot is unusually shaped or sized, we can usually find a standard size that fits — or in some cases install a standard filter cabinet during a tune-up.
A Filter Schedule That Sticks
The biggest barrier to filter changes is forgetting. Three approaches that work:
Calendar reminder
60-day reminder on your phone. Set it to repeat.
Subscription delivery
Filter subscription services deliver new filters on your schedule. When they arrive, you change the filter. No forgetting.
Tie it to something you do anyway
Change the filter when you pay your heating bill. When you do monthly home maintenance. When the seasons change. Pick a trigger and stick to it.
What We Check During a Tune-Up
During a professional HVAC tune-up, the filter is one of many things we inspect and handle:
- Verify the correct filter size and MERV rating are in use
- Check for gaps around the filter that allow bypass airflow
- Measure static pressure across the filter
- Replace with a fresh filter
- Recommend a change schedule based on your specific system and household
Two tune-ups a year (spring for cooling, fall for heating) with filter changes between visits is the schedule most Salem homes do best on.
How We Do It at CHS
We sell filters at cost to our customers — we’re not making our money on them. During tune-ups we verify your filter setup is correct for your system. If we see issues (wrong size, wrong MERV, bypass gaps) we fix them. Salaried technicians, not commissioned. Family-owned in Salem since 2001. Licensed and insured under CCB# 147550.
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Ready to Talk to Stan?
No pressure, no surprises — just honest advice from a team that’s been keeping Salem homes comfortable since 2001.
Call or text: (503) 581-6999
Email: chssatt@gmail.com
Service area: Salem, Keizer, Dallas, Monmouth, Independence, Silverton, Stayton, Aumsville, Sublimity, Albany, Woodburn, Scio, and surrounding Mid-Willamette Valley communities.
Licensed & insured: CCB# 147550
Call or text for a free estimate or to book a tune-up. We’ll verify your filter setup is right for your system and your household.