MERV stands for Minimum Efficiency Reporting Value — the industry-standard scale that tells you how much your furnace filter actually catches. It runs from 1 to 16 for home filters: the higher the number, the smaller the particles the filter traps. For most Edmonton-area homes, a MERV 8 to 11 pleated filter is the practical sweet spot.
MERV is a rating set by ASHRAE (the heating and air-conditioning standards body) that scores a filter on how well it removes particles from the air passing through it. The test measures capture across a range of particle sizes — dust, pollen, pet dander, mould spores, smoke and finer particles — and boils it down to a single number. A higher MERV means the filter holds onto smaller, harder-to-catch particles. It is the one apples-to-apples number you can compare between brands, instead of vague marketing words like “allergen” or “premium.”
| MERV | What it captures | Typical use |
|---|---|---|
| 1–4 | Large particles only — lint, dust, carpet fibres | Cheap fibreglass “throwaway” filters; protects the furnace, not your air |
| 5–8 | Adds finer dust, mould spores, pollen, pet dander | Good everyday home filtration; MERV 8 is a solid baseline |
| 9–11 | Adds finer pet dander, smog particles, fine dust | The home sweet spot — better air without choking airflow |
| 12–13 | Catches very fine particles, some smoke and bacteria | Allergy/asthma homes & wildfire smoke — only if your system handles it |
| 14–16 | Near-HEPA capture of very fine particles | Hospitals & labs — usually too restrictive for a home furnace |
It’s tempting to grab the highest number on the shelf, but a denser filter is harder to pull air through. If you fit a filter that’s too restrictive for your furnace, you can starve the system for airflow — which makes it work harder, run longer, heat or cool unevenly, and in some cases ice up the A/C coil or strain an older blower motor. The goal isn’t the highest MERV; it’s the highest MERV your specific furnace can comfortably breathe through.
A few things that affect what your system can handle:
For the typical Edmonton-area home, a MERV 8 to 11 pleated filter is the sweet spot. It captures the dust, pollen and pet dander that matter for everyday air quality while still letting your furnace breathe. Step up toward MERV 13 only if someone in the home has allergies or asthma, or during wildfire smoke season — and only if your system is rated for it.
If you’re running a 1” filter, plan to change it about every 1–3 months (more often with pets or during smoke season). Thicker 4”–5” media filters can often go 6–12 months. Not sure what your furnace can take? That’s an easy thing for us to check when we’re out — we’ll tell you the right MERV for your exact system, no guesswork.
We’ll check your system and recommend the right MERV rating and filter size for your home — honest advice, no pressure.