Alen BreatheSmart FLEX Review In 2022

Modern yet classic design. Alen BreatheSmart FLEX HEPA air purifier is slotted below Classic and Fit50 yet retaining all the essential purifying goodness. Nicely balanced between airflow distribution and purifying applicable area, are there any features left out? What is unique about Alen BreatheSmart FLEX air purifier that could distinctive itself ahead of its contenders? Head over to our full review and see the differences along with pros and cons.
online price (US)**
±349.00 $$$$/ 7

(annual filter cost ±39-118)

** MRSP (Manufacturer's Suggested Retail Price)/ RSP (Retail selling price) is accurate at the time of posting.
^ Annual filter cost is calculated based on filter price and 12 hours of usage. Pricing could vary depending on air quality, usage frequency, and speed.
` The indicated online price guides as follows: $ = under $50, $$ = $50-100, $$$ = $101-200, $$$$ = 201-300, $$$$$ = $301-400, $$$$$$ = 401-500, $$$$$$$ = over $500.

Alen BreatheSmart FLEX Specification

ProductAlen BreatheSmart FLEX
15 x 25 x 8.5 in
(38.1 x 63.5 x 21.6 cm)
Weight15 lb (6.8 kg)
Coverage (up to)700 sq. ft. (65 m2)
Airflow speed53-187 cfm (90-318 m3/h)
Dust free (CADR)245 cfm (416 m3/h)
Pollen free (CADR)245 cfm (416 m3/h)
Smoke free (CADR)245 cfm (416 m3/h)
Humidifying(H) speed
- Lifespan
- Replacement cost ($)
Washable Pre-filter (with HEPA filter)
6 - 18 months
HEPA filter
- Lifespan
- Replacement cost ($)
HEPA-Pure Filter FL40
6 - 18 months
+- 59
Carbon filter
- Lifespan
- Replacement cost ($)
Ionizer/ Technologies
UV-light/ PCO
Other filter
All-in-one filter
- Lifespan
- Replacement cost ($)
Optional/ Addon
6 - 18 months+- $79
HEPA-OdorCell Filter FL40-MP
6 - 18 months+- $89
HEPA-Fresh Filter FL40-CARBON
6 - 18 months+- $69
Noise level39 - 55 dB
Power usage level36 W
Timer/ Scheduler2, 4, 12 hours
Auto mode
Air qualityAQ indicator
Filter change indicator
More color options
Wi-Fi/ BTBluetooth
Remote control
Child lock
WarrantyLifetime Limited Warranty
Email/ Phone support

Key Features

  • 2-stage filtration (3-stage with optional filter upgrade)
  • Washable Pre-filter/ HEPA-Pure filter
  • 4 fan speeds
  • Personalizable front cover
  • Child-lock control panel and child-safe vent guard
  • 4, 8, 12 hour timer
  • Lifetime limited warranty
  • [Optional] filters - HEPA-Silver filter, HEPA-FreshPlus filter, HEPA-OdorCell filter

Design And Usability

Alen BreatheSmart FLEX dimension
15 x 25 x 8.5 in
(38.1 x 63.5 x 21.6 cm)
Alen BreatheSmart FLEX weight
15 lb (6.8 kg)

The shrunk version of the Classic BreatheSmart model, Alen BreatheSmart FLEX is a well-designed air purifier that comes with a smaller dimension at 15 x 25 x 8.5 in. Weight-wise, it is at a reasonable 15 lb inclusive of the filter set. You can effortlessly move it around for room to room purifying. Fitting quality remains unchanged with zero air bypass detected during the course of the test. What’s also remains is the swappable front cover panel where you could choose an ideal wood trim design to suit your home decor. Underneath the front panel, you will find air inlets located at the sides and bottom while the air outlet is located behind at the top. A carrying handle is also at the back right beneath the outlet.

Alen BreatheSmart Flex Control

Shifting our attention to the top control panel, there are 6 clearly labeled round buttons and dedicated indicator lights above each button. Unlike the previous version, Alen BreatheSmart FLEX HEPA air purifier has a capacitive touch panel which means each button only requires a light touch and a chime can be heard to reassure your action. To turn on the air purifier, press the middle Power button. Press again to turn off all indicator lights and again to turn off the air purifier. At this point, you can start adjusting the air purifier fan speed. Press the Speed button repeatedly to loop between Speed 1, 2, 3, T (turbo). The indicator above will show you what speed you are currently in. The same goes with the Timer button that press repeatedly will cycle between 2, 4, 12 hours. Moving to the left, the Filter life button allows you to reset the filter countdown timer by pressing and holding the button for 5 seconds. Do this after you have successfully changed to a new filter or when the indicator light turns gradually from Green, Yellow to Red (traffic light style). Finally, you can lock the control from any modification or fiddling from your kids by pressing and holding the Lock button for 3 seconds. The 2 buttons missing out from BreatheSmart Classic series is the Auto and Ion button as they are omitted here.

Other common sets of features include your pre-selected HEPA filter, 4 fan speeds, air quality display, basic filter replacement indicator, Child lock/ Auto-off safety feature activates when the front cover is not tightly closed. Alen BreatheSmart FLEX is UL listed, ENERGY STAR rated, and protected by Alen’s unique Lifetime limited warranty.

Airflow, Coverage, And CADR

Alen BreatheSmart FLEX coverage
Purifying coverage
700 sq. ft. (65 m2)
Alen BreatheSmart FLEX fanspeed

With a smaller overall size, Alen BreatheSmart FLEX HEPA air purifier has a reduced purifying coverage at 700 sq. ft with 2 air changes per hour. That by no means is poor where it is still ideal for most room sizes including bedroom, kitchen, basement, garage, and typical household living room. Airflow delivery rate also drops when compare to BreatheSmart Classic especially on lower speed; expect speed 1 at 53 cfm, speed 2 at 135 cfm, speed 3 at 147 cfm, and turbo at 187 cfm. Another trade-off is the lack of Auto mode within the 4 selectable speeds.

BrandPurifying CoverageFan Speed
Alen BreatheSmart FIT50900 sq. ft.4
Austin Air HealthMate Plus1,500 sq. ft.3
Pure Enrichment PureZone Elite>190 sq. ft.3
Rabbit Air BioGS 2.0 SPA-550A550 sq. ft.5
PureZone 3-in-1 True HEPA200 sq. ft.3
InvisiClean Aura II 4 in 11,276 sq. ft.4
Alen BreatheSmart FLEX dust CADR
245 cfm (416 m3/h)
Alen BreatheSmart FLEX pollen CADR
Pollen CADR
245 cfm (416 m3/h)
Alen BreatheSmart FLEX smoke CADR
Smoke CADR
245 cfm (416 m3/h)
Although not tested in the typical channel, Alen BreatheSmart FLEX HEPA air purifier dust, pollen, and smoke CADR are equally impressive at an estimated 245 cfm overall. It covers large particles e.g. dust, hair, lint to the smaller allergens like pollen/ mold would be captured by the air purifier. Smoke and odors particles would fall into the air purifier checklist if the right type of filter is used i.e. HEPA-Fresh filter (optional add-on purchase).

Recommended Read

Filters And Performance

Utilizing the same one filter kit setup, the initial velcro attached pre-filter above the HEPA filter is great at removing visible airborne particles while prolonging the HEPA filter lifespan. Moving on to the primary HEPA filter, you can select one of the 4 available HEPA filters to trap micron-size particles with each having its unique specialty. The standard HEPA-Pure filter is cheap and effective against common household allergens but lacks any deodorization filtration. HEPA-Silver filter is very effective against mold, germ type bacteria. Our favorite HEPA-FreshPlus is great against asthma triggers chemicals, VOCs, and smoke, HEPA-OdorCell is best used to neutralize odors from diapers or pets. Regardless of which filter options you choose, all filter kit shares the same size and build quality as you would expect. An optional Ionizer is also available in the air purifier that release negative ions to pull airborne particles down for the filter to capture.

Filter maintenance and care

Begin by unplugging Alen BreatheSmart FLEX HEPA air purifier to prevent an electric short circuit. Then pull out the front panel starting from the 2 bottom sides of the cover. With the filtration exposed, continue removing the old filter by pulling the pull strings. Remove the plastic wrap from the new filter and place it with the pull strings facing outwards. Snapback the front panel via the top tabs and your air purifier is good to go. You can prolong the HEPA filter lifespan by washing the removable pre-filter attached to it. First, peel off the black layer foam held on with Velcro, then lightly vacuum or clean the pre-filter from any trapped particles. Stick it back to the HEPA filter once done. You only need to spend 2 minutes of your time every 6 to 18 months period to repeat the maintenance.

Noise And Energy Usage

Alen BreatheSmart FLEX noise level
Noise level
39 - 55 dB
Alen BreatheSmart FLEX power consumption
Power consumption
36 W
Even without the WhisperMax technology incorporated, Alen BreatheSmart FLEX HEPA air purifier is comparatively more silent than the standard BreatheSmart version at only 39 - 55 dB noise level. In a real-life scenario, you can hardly tell apart between the 2. No problem running in the bedroom however, the lack of Auto mode is a bit of a let-down, especially in nighttime use. Moving to power consumption, at an average of 36 watts hourly, power usage is low on this Energy Star unit and you can clearly see the difference in your electricity bill in long-run.
Noise TypeDecibels
Alen BreatheSmart FLEX39 - 55 dB
Breathing10 dB
Rustling leaves20 dB
Whispering/ Quiet library30 dB
Light rainfall40-50 dB
Conversation50-60 dB
Vacuum cleaner/ Hair dryer/ Washing machine65-80 dB
City traffic80-90 dB

Pricing And Maintainence Cost

Alen BreatheSmart FLEX MRSP/ RSP
+- 349.00
Alen BreatheSmart FLEX annual filter replacement cost
Annual Filter Cost
+- 39 - 118
^ Replacement filters/ estimated cost
Alen BreatheSmart FLEX HEPA air purifier is the cheapest in the BreatheSmart series but there is some compromisation. Other than the weaker purifying performance, the lack of air quality indicator, sensor/ auto mode, and a basic filter replacement indicator is part of the deal. Annual filter replacement is the cheapest in its series although not by much. Filter availability is great where you could easily purchase anyone of the replacement filters online as Alen still making it. Ignoring the price factor, Alen BreatheSmart Classic/ Fit50 seems like a better deal as both come with Auto mode.
On to buying Alen BreatheSmart Flex, Beside the physical store like Lowe's, Home Depot, Target where you can get a hold on the HEPA air purifier, we recommend buying straight from Amazon as it is convenient, 30 days money back guarantee, free shipping (selective location) and comes in a cheaper bundled deal. Alen's official website is another worthy place to consider that offers a wider selection of front panel design, 60 days money-back guarantee, free shipping to the U.S. continent, and also bundled/ family pack deal.

Alen BreatheSmart FLEX VS The Challengers

Alen BreatheSmart FIT50

Alen BreatheSmart FIT50

Higher purifying coverage (up to 900 sq. ft.) with SmartSensor and Auto mode. The downside is the higher price tag and a lower CADR output which is a surprise to many. Alen BreatheSmart Fit50 also might be at the end of its life cycle so expected limited stock availability.
Alen BreatheSmart HEPA Air Purifier Review

Alen BreatheSmart Classic

Standard version with the highest price tag but comes with the best purifying coverage, airflow performance, and full set of features including the sorely missed SmartSensor for Auto mode. Being the longest-running model in the BreatheSmart lineup, Alen BreatheSmart Classic is also the air purifier that holds the best possible online deal.
Rabbit Air MinusA2 Air Purifier Review SPA-780N

Rabbit Air MinusA2 SPA-780N

If you do not mind topping up a little bit more cash, Rabbit MinusA2 has more filtration depth than flex (6-stage VS 3-stage) and a more adaptable frame body that you can hang just about anywhere. Otherwise, both air purifiers have the same customizable filters and front panel design.
Coway Airmega 300 Review

Coway Airmega 300

As both air purifiers offer an identical set of features and sensors, Airmega 300 stands out in its design, airflow distribution, and purifying coverage but comes at a higher cost. You also have to give up the option to customize your main filter and front panel design.

Final Thoughts On Alen BreatheSmart FLEX

Bring to a conclusion, Alen BreatheSmart FLEX HEPA air purifier is remarkable and 87% of 4 – 5 stars users think this is the best air purifier in its class to cover against household contaminants and allergies. The option to choose the right type of filters based on their needs is a big plus. People also like how fast and effective it can purify their indoor air. On the opposite spectrum, the small 13% users that gave it 1 -3 stars do not feel this is a justifiable purchase or simply think the air purifier does not work at all. There are also complaints about the customer service but that is a few rare cases. Comparing the all-around advantages/disadvantages, you can most definitely see there are more strong points on Alen BreatheSmart FLEX than the negative points.


  • Changeable front panel with tons of modern wood trim design.
  • Consistent and strong airflow delivery rate that supports the wide purifying area.
  • Up to 3 optional filter upgrade that is excellent against allergens and odors.
  • Longer lasting filters compare with similar segment air purifiers.
  • Built-in timer (2, 4, 12 hours).
  • Child friendly machine with child lock control panel and safe vent guard.
  • Lifetime Limited Warranty (with product registration & active filter subscription).


  • Lacks odor filtration on the default HEPA-Pure filter.
  • No dedicated odor carbon filter for extra smoke filtration.
  • Noisy at highest fanspeed although not the worst in its class.
  • Lacks advanced filter replacement indicator (only basic version), SmartSensor (thus Auto mode), Ionizer. All these are available in BreathSmart FIT50.
Alen BreatheSmart FLEX Air Purifier Review

Max Fernandez

A loving father and a dedicated reviewer for airfuji.com with more than 1000 air purifiers under his belt. Max Fernandez is also one of the million patients currently suffering from asthma. Feel free to nudge him if you have any questions.
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