Air PurifiersSmall Room
Levoit LAP-B851S-WNA Air Purifier Manual
Setup, everyday use, maintenance and troubleshooting for the air purifier for rooms up to 132 sq. ft., with verified specifications.
- Room sizeUp to 132 sq. ft.
- Smoke CADR85 CFM
- Efficiency5.6 CFM/W
- Est. yearly cost$15.30
About the Levoit LAP-B851S-WNA
The Levoit LAP-B851S-WNA is an air purifier for rooms up to 132 sq. ft., certified under the ENERGY STAR program.
Its clean air delivery rate (CADR) is 85 CFM for smoke, 90 CFM for dust, and 109 CFM for pollen, with a PM2.5 CADR of 87 CFM. In a 132 sq. ft. room with an 8 ft ceiling, the smoke CADR works out to about 4.8 air changes per hour.
Air passes through a HEPA filter. It also has Wi-Fi connectivity.
Efficiency is rated at 5.6 CFM of PM2.5 clean air per watt (integrated energy factor). That beats 41% of the 76 Small Room models in our database. The certification test recorded no ozone emissions. It also meets the ENERGY STAR Most Efficient criteria.
Specifications
| Brand | Levoit |
|---|---|
| Model number | LAP-B851S-WNA |
| Size class | Small Room |
| Recommended room size | 132 sq. ft. |
| Smoke CADR | 85 CFM |
| Dust CADR | 90 CFM |
| Pollen CADR | 109 CFM |
| PM2.5 CADR | 87 CFM |
| Integrated energy factor (PM2.5 CADR per watt) | 5.6 CFM/W |
| Smoke CADR per watt | 5.86 CFM/W |
| Annual energy use | 90 kWh/yr |
| Cleaning technology | Fan and Filter |
| Filter type(s) | HEPA |
| Ozone emissions | 0.00 ppb |
| Smart / connected features | Yes |
| Connectivity | Wi-Fi |
| ENERGY STAR Most Efficient | Yes |
Safety information
- Plug the purifier directly into a working household outlet. Do not run the cord under rugs or furniture, and do not use a damaged cord or plug.
- Unplug the unit before opening the filter door, changing filters or cleaning it.
- Do not operate the purifier without its filters installed, and use only filters intended for this model.
- Keep the air inlet and outlet clear; never insert objects into the grilles or let children play with the unit.
- Do not use the purifier near water, in a bathroom while showering, or where flammable vapors or aerosols are present.
- An air purifier does not remove carbon monoxide or radon and is not a substitute for ventilation. Keep CO alarms in the home.
Installation and first-time setup
- Remove packaging from the filters
Open the filter door and take every filter out of its plastic bag. Running the purifier with filters still wrapped blocks airflow and can overheat the motor.
- Reinstall filters in order
Fit the filters back in the order and orientation marked on their frames. Most filters have an airflow arrow; it should point toward the fan.
- Choose a location
Place the purifier on a firm, level surface in the room where you spend the most time, with at least a foot or two of clearance from walls, curtains and furniture on the intake and outlet sides.
- Size the space
This model is rated for rooms up to 132 sq. ft. (12 m²) with standard 8 ft ceilings. For higher ceilings, open-plan areas or allergy and smoke concerns, treat a smaller area or add a second unit.
- Power on and reset indicators
Plug in, run the unit on high for a few minutes, and reset the filter-life indicator if the manual asks you to after installing new filters. Then pair the purifier with the manufacturer's app.
| Room area (8 ft ceiling) | Air changes at smoke CADR |
|---|---|
| 130 sq. ft. | 4.9 per hour |
| 100 sq. ft. | 6.4 per hour |
| 65 sq. ft. | 9.8 per hour |
Using your air purifier
Choosing a fan speed
Run the purifier continuously — particles are released all day, and a purifier only cleans the air that passes through it. Use high speed for 20–30 minutes after cooking, cleaning or when smoke is present, then drop to a lower, quieter speed for everyday use. The 85 CFM smoke CADR is measured at the highest speed; lower settings deliver proportionally less clean air.
App control
This model can be controlled over Wi-Fi from the manufacturer's app, which typically lets you change speed, view air-quality readings, set schedules and track filter life remotely.
Getting the best results
- Keep doors and windows in the room closed while the purifier runs so it is not trying to clean outdoor air.
- Remove the source where possible: vacuum with a HEPA vacuum, wash bedding weekly and keep pets out of the bedroom if they trigger allergies.
- Position the purifier near where you sit or sleep, with its outlet unobstructed, for the most noticeable benefit.
- Change filters on schedule; a loaded filter reduces CADR and can release odors.
Care and maintenance
| When | What to do |
|---|---|
| Every 2–4 weeks | Vacuum the pre-filter or outer mesh (if fitted) to remove hair and lint, and wipe the intake grille. |
| Every 6–12 months | Replace the main HEPA filter when the indicator lights or as the manual specifies. Do not wash or vacuum the pleated media — it damages the fibers. |
| As needed | Wipe the cabinet with a dry or slightly damp cloth. Never spray cleaners into the grilles. |
Troubleshooting
Most air purifier issues relate to filters, placement or the filter-door safety switch. Work through these checks before contacting support. If the display shows a code, consult the code table in your manufacturer's manual.
| Problem | Possible cause | What to try |
|---|---|---|
| Unit will not turn on | Filter door not fully closed (safety switch); outlet not live; child lock on. | Close the filter door firmly; try another outlet; check the manual for unlocking the controls. |
| Weak airflow | Filter still in its bag or overloaded; intake blocked. | Remove packaging, replace or clean filters, and clear space around the intake. |
| Louder than usual | Filter loaded or misaligned; unit on an uneven surface; debris in the fan. | Reseat or replace the filter, move to a level surface, and unplug before checking the fan area. |
| Odor from the unit | Filter has absorbed cooking or smoke odors; new-filter smell. | Replace or clean the filter as the manual directs; run on high in a ventilated room for a few hours if the filter is new. This model has no activated-carbon stage, so it is not designed for odor removal. |
| Filter light stays on | Indicator not reset after replacing the filter. | Follow the manual's reset procedure, usually holding the filter button for several seconds. |
| Air still feels dusty | Room larger than the rating; doors or windows open; purifier on lowest speed. | Compare the room to the 132 sq. ft. rating, close the room, and run a higher speed. |
| App cannot find the purifier | Phone on a different network band; router out of range. | Pair while standing near the unit, confirm your Wi-Fi network is supported by the app, and restart the purifier and router. |
Energy use and running costs
The Levoit LAP-B851S-WNA is rated at 90 kWh per year, an ENERGY STAR estimate that assumes the purifier runs about 16 hours a day and sits in standby the rest of the time. At an average electricity price of $0.17 per kWh, that is about $15.30 per year, or $1.28 a month.
At the high-speed setting used for its CADR test it draws roughly 15 W, so running flat out around the clock would use about 127 kWh a year ($21.60). Everyday operation on a lower speed uses considerably less.
The integrated energy factor of 5.6 CFM/W means every watt delivers about 5.6 cubic feet per minute of PM2.5-free air, including standby losses. Higher numbers mean more clean air for the same electricity.
Replacement filters are usually a larger running cost than electricity, so factor their price and replacement interval into your budget.
Frequently asked questions
What size room is the Levoit LAP-B851S-WNA designed for?
It is rated for rooms up to 132 sq. ft. with 8 ft ceilings, which corresponds to about 4.8 air changes per hour at its 85 CFM smoke CADR. For allergies or smoke, use it in a smaller room or run it on high.
What is the CADR of the Levoit LAP-B851S-WNA?
Its clean air delivery rates are 85 CFM for smoke, 90 CFM for dust, and 109 CFM for pollen, plus a PM2.5 CADR of 87 CFM. Higher CADR means faster cleaning.
Does the Levoit LAP-B851S-WNA use a true HEPA filter?
Yes. The certification lists a HEPA filter. True HEPA media captures at least 99.97% of 0.3-micron particles.
Does the Levoit LAP-B851S-WNA produce ozone?
Its certification test recorded 0 ppb of ozone.
How much electricity does the Levoit LAP-B851S-WNA use?
It is rated at 90 kWh per year, about $15.30 at $0.17/kWh, assuming roughly 16 hours of operation a day.
Can I control the Levoit LAP-B851S-WNA from my phone?
Yes. It is connected-capable over Wi-Fi.
Sources and disclaimer
Specifications on this page come from the ENERGY STAR certified air purifiers dataset published by the U.S. Environmental Protection Agency (record certified July 23, 2025), retrieved October 7, 2026.
The setup, operating, maintenance and troubleshooting guidance is written by ManualHarbor's editors for this specific product type and configuration. It is an independent guide — not a reproduction of the manufacturer's manual — and ManualHarbor is not affiliated with Levoit. Always follow the safety instructions, installation requirements and warranty terms supplied with your unit, and contact Levoit or an authorized service provider for warranty repairs and replacement parts.
Running-cost figures use assumed U.S. average utility prices and are estimates for comparison only. See our editorial methodology for details.
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