Genuine Lennox X6666 — This is the factory OEM MERV 16 filter for your PCO-12C or HCFPCO-12C Healthy Climate PureAir system. Not a compatible or aftermarket substitute.
The X6666 is Lennox's highest-efficiency residential filter, capturing over 95% of airborne particles down to 0.3 microns—including dust, pollen, mold spores, pet dander, bacteria, and smoke particles. If your PureAir system came with MERV 16 filtration, this is the exact replacement Lennox specifies.
Filter Specifications
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Lennox Part Number: X6666, 100908-04
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Nominal Size: 17" x 26" x 4"
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Actual Size: 16-5/8" x 26" x 4"
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MERV Rating: 16 (highest residential rating)
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Fits Units: PCO-12C, Filter part number HCFPCO12-16 & HCFPCO12-10
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Airflow Capacity: 1200 CFM
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Replacement Interval: Every 9-12 months
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Pack Size: 1 filter
X6666 vs X6664: Understanding the Difference
Both filters fit the same PCO-12C housing, but they deliver very different performance:
X6666 (This Filter) — MERV 16
Captures 95%+ of particles down to 0.3 microns. Hospital-grade filtration. Best choice for allergies, asthma, pets, or anyone wanting the cleanest possible air. This is what Lennox installs in PureAir systems configured for maximum filtration.
X6664 — MERV 11
Captures 85% of particles down to 1.0 micron. Standard filtration adequate for general use. Lower cost, but won't trap the ultrafine allergens, bacteria, and smoke particles that MERV 16 catches.
If you're seeing X6664 filters priced lower online, that's why—it's a less efficient filter, not the same product at a better price.
What's in the Box
- 1x Genuine Lennox X6666 MERV 16 Pleated Filter
- Factory sealed, ready to install
- No assembly or tools required
Cross-Reference Part Numbers
This filter is also listed as: X6666, 100908-04, Healthy Climate X6666, Lennox PureAir MERV 16
Looking for a Compatible Alternative?
We also manufacture a USA-made MERV 16 compatible for the PCO-12C at significant savings. Same dimensions, same MERV 16 rating, made in America. A great option if you want high-efficiency filtration at a lower price point.
Why Order From Atomic Filters?
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Same-Day Shipping: Orders placed before 11:30 AM EST ship today (Mon-Fri)
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Free Delivery: No minimum order required
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Genuine OEM: Factory Lennox filter, not aftermarket
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In Stock: Ready to ship from our North Carolina warehouse
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Real Support: Questions? We're HVAC filter specialists
