Knka APH4000 Air Purifier: CADR, Noise, Coverage & Specs
Last verified: Aug 22, 2026
Aug 2026
Quick verdict
The Knka APH4000 is best suited to medium rooms where high airflow and quiet minimum operation are priorities. Its 226 CFM smoke CADR supports about 350 sq ft at approximately 4.8 air changes per hour. Buyers should separately evaluate filter cost and maximum-speed noise before deciding.
Best for
- Living rooms and medium bedrooms
- Low-noise minimum settings
Consider alternatives if
- You need a verified maximum-speed noise figure
- Filter replacement interval or cost is a deciding factor
- You are planning around the manufacturer coverage claim rather than CADR-based room size
Verified strengths
- 226 CFM smoke CADR (~350 sq ft at ~4.8 ACH)
- 22 dB published minimum noise
- HEPA filtration (as published)
Verified limitations or missing information
- Maximum-speed noise is not in our sources
- Filter replacement interval is not verified
Knka APH4000 overview
The Knka APH4000 is a medium-room air purifier with a smoke CADR of 226 CFM. Based on our CADR-based room-size method, it is suitable for approximately 350 sq ft. It includes HEPA filtration and 22 dB minimum noise.
- Smoke CADR
- 226 CFM
- Recommended room size
- 350 sq ft
- Claimed coverage
- 1695 sq ft
- Minimum noise
- 22 dB
- Filter type
- HEPA
- Power
- 45 W
- Weight
- 9.7 lb
- Last verified
- Aug 22, 2026
Knka APH4000 CADR and room size
Recommended room size is about 350 sq ft (CADR × 1.55). That is approximately 4.8 air changes per hour in a room with an eight-foot ceiling. The manufacturer figure of 1695 sq ft corresponds to about 1.0 air change per hour at the same ceiling height and is shown separately. Our recommended room size uses approximately 4.8 air changes per hour with an eight-foot ceiling. Manufacturer coverage figures may use a lower air-change rate and are shown separately.
The manufacturer coverage claim is higher than 3× CADR, so it is not used for ranking.
Knka APH4000 noise level
Published minimum noise is 22 dB.
Maximum-speed noise is not in our sources.
Knka APH4000 filtration
Published filter type: HEPA.
Filter replacement interval is not verified in our sources.
Knka APH4000 smart features
AQI Display, Washable Pre-Filter, ECO Mode, Sleep Mode
Knka APH4000 specifications
- CADR (smoke)
- 226 CFM
- Recommended room size
- 350 sq ft
- Manufacturer claimed coverage
- 1695 sq ft
- Minimum noise
- 22 dB
- Filter type
- HEPA
- Power
- 45 W
- Weight
- 9.7 lb
About Knka air purifiers
Knka models in this catalog are compared by CADR, recommended room size, noise, and filter type.
Knka APH4000 comparisons
What is the CADR of the Knka APH4000?
Smoke CADR is 226 CFM.
What room size is the Knka APH4000 suitable for?
About 350 sq ft at approximately 4.8 air changes per hour with an eight-foot ceiling.
How loud is the Knka APH4000?
Minimum reported noise: 22 dB.
Does the Knka APH4000 have Wi-Fi?
No published Wi-Fi or app control in our sources.
What filter does the Knka APH4000 use?
HEPA.
Methodology
Specifications are compiled from manufacturer documentation, product listings and other cited sources.
How we calculate recommended room size.
Sources
All air purifiers · Best air purifiers for allergies · Methodology