Alen is a well-known brand in the world of air purifiers and the Austin-based company has been building air purifiers since 1999. They currently have 72 employees and had a revenue of just under 30 million dollars last year.
One of their stand-out features is a lifetime guarantee — unique in the air purifier industry, but it does require you to sign up for their filter subscription. We have already reviewed the Alen 75i and 45i, which impressed us, although they are a little pricier than competitors with similar air cleaning performance.
The Alen Breathsmart Flex is based on the 45i but lacks the ionizer and smart features. It still has a similar level of air-cleaning power and looks very similar. We were keen to test the performance of the Breathsmart Flex in our home and see if it matched the performance of the Alen 45i.
Most air purifier reviews are just pictures and overly optimistic write-ups. Journalists at these publications are biased to sell the unit without digging deeper than running the air purifier a few times. We don’t have deals with manufacturers or a big corporation watching what we say, and we have no problem saying if an air purifier is terrible.
We don’t just take manufacturers at their word, either; we test all our units in our home lab to see how well they remove particles and share this data directly with you.
On paper, the Alen BreatheSmart Flex is very similar to the Alen 45i, although it lacks many smart features and an ionizer function. Read on to find out what differentiates these two Alen air purifiers.
The lowdown on the Alen BreatheSmart Flex
What we really like
What we think could be better
| HouseFresh rating: | ★★★★☆ |
| Time to clean our 728 cubic feet test room (with the device running at top speed): | 34 minutes |
| Air purifier technology: | H13 HEPA with an option for activated charcoal (Fresh, Odorcell and Heavy Smoke options available) |
| Recommended room size (4.8 air changes per hour): | 296 sq. ft. |
| Clean air delivery rate (CADR): | Dust: 208.8 CFM Smoke: 191 CFM Pollen: 245.4 CFM |
| Dimensions (in inches / in cm): | 25H x 15W x 8.5D inches (63.5 x 38.1 x 21.59 cm) |
| Weight (in pounds / in kg): | 15 lbs (6.8 kg) |
| Filter life: | 9-12 months |
| Noise level in decibels (measured from 3 ft. away with a sound level meter): | Speed 1: 35.7 dB Speed 2: 45.5 dB Speed 3: 50.7 dB |
| Electricity consumption in watts (recorded with an electricity usage monitor): | Standby mode: 0.8 watts Speed 1: 2.9 watts Speed 2: 6.3 watts Speed 3: 14 watts Speed 4: 24.2 watts |
| Estimated running cost (electricity consumption + official filter replacement): | $105.91 per year |
| Cost per CADR cfm (based on dust CFM as reported by AHAM): | $1.21 |
| Manufacturer’s warranty: | Lifetime (with product registration & active filter subscription) |
| Country of manufacture: | China |
A fairly standard “Alen-looking” air purifier
The Alen Flex has a simple design and a small footprint considering its power.
You get a fairly standard Alen design with the Alen Flex, with a shiny white cover and a control panel on top. This is the same design you will see across other Alen devices in the BreatheSmart series such as the 45i and the 75i.
It doesn’t particularly stand out, but it’s also unlikely to be something to start a conversation for the wrong reasons.
The control panel is simple and straightforward, in line with other air purifiers by Alen.
From left to right:
- Filter indicator with three lights (green, yellow, red) to warn you when the filter needs to be replaced
- Timer button to set the air purifier so it runs for 2, 4 or 12 hours before turning off automatically
- Power button in the center to turn the unit on and off
- Speed button to switch between fan speeds (with the highest being Turbo speed)
- Lock button which allows you to lock the control panel after pressing and holding it for three seconds
Comparing the Alen Flex with the Alen 45i
If you have been researching Alen air purifiers for a while, you are likely to have run into another unit that looks A LOT like the Flex: the Alen BreatheSmart 45i.
When comparing the Flex to the 45i side by side, you will see that they both look as if they were to have been built from the same mold, with nearly identical design:
Both the Alen 45i and the Alen Flex have many of the same features, such as the child safety guard and a removable front cover that can be swapped out for five different colors.
The biggest difference comes when you compare the control panel of both units side by side:
The control panel of the Alen Flex lacks buttons for the ionizer, auto mode and options for adjusting the light.
That means that unlike the 45i, the Flex doesn’t come in an in-built ionizer function (yay for those who prefer mechanical filtration only!) or with an auto mode (it does however come with a timer function, which is not the same but it’s good to have).
Something worth noting: The Flex does not offer app support.
That said, you can connect your Alen Flex with the Alen air quality monitor, enabling you to understand your air quality and enable intelligent air purifier features. However, the monitor costs $129.
If smart functions are important to you, you should consider going for the Alen BreatheSmart 45i instead as it will offer more bang for your buck.
High quality customizable filters
As default you will get medical-grade H13 HEPA filtration, but you can choose different levels of carbon filtration as well.
As with all the Alen air purifiers, you will get to pick from four different options when buying your Flex:
| B4-Pure Filter | Captures allergens, dust, mold, and germs |
| B4-Fresh Filter | All of the above + carbon to absorb common household odors |
| B4-Odor Filter | All of the above + odor neutralizer to absorb pet odors and other unwanted smells |
| FL40-H Heavy Smoke Filter | All of the above + 2.3 lbs of active carbon to absorb chemicals, VOCs and smoke |
Every single Alen filter includes medical-grade H13 HEPA filtration that captures 99.9% of particles as small as 0.1 micron (e.g. dust, allergens, and harmful fine pollutants).
That said, my recommendation would be to get at least the FL40 Filter, as it comes with 2.3 lbs of activated carbon that can help remove unwanted smells and dangerous gases from the air.
The additional cost on top of the basic B4-Pure Filter is not a lot, and you will get an activated carbon filter in addition to the H13 HEPA filter:
But if you just want an air purifier for allergies and do not need gas or odor removal, you can save a little money with the B4-Pure Filter filter option.
As with many HEPA-based air purifiers, the filters for the Alen Flex arrive inside a plastic bag, so be sure to remove them from the wrapping before you use them.
I was pleased to report that the Alen Flex filter had an ample red warning to remove the plastic, so I can’t imagine anyone ignoring this. I wish more air purifier manufacturers would do this.
Changing the filter in the Alen BreatheSmart Flex is pretty straightforward. You just need to remove the back panel and you will be able to access the filters. Check out the video below for a step-by-step guide:
The Alen Flex cleared our test room in 34 minutes
That’s the exact same time it took the more expensive Alen 45i, which uses an ionizer!
As with all the reviews we produce at HouseFresh, we tested the Alen Breathsmart Flex in our test room, which measures 728 cubic feet. We burned an incense stick to simulate indoor pollution and used two Purpleair laser particle counter sensors to record how long it took for the Alen Flex to remove PM1, PM2.5 and PM10 particles from the air.
You can see the test results in the chart below:
As you can see, the Alen Flex cleaned our test room at the exact same speed as the upgraded Alen BreatheSmart 45i. It will be effective for small to medium-sized rooms. For those with large rooms, you will want to look at the much larger Alen 75i.
Noise levels test results, compared
As with the Alen 45i, the Flex is one of the quietest air purifiers we have tested here at HouseFresh. At its highest level, it hits a maximum of 50.7 dB(A), less than the sound generated by a standard refrigerator.
In comparison, many air purifiers with similar power levels can reach beyond 55 dB and the Mila and IQAir Healthpro Plus go up to 59.2 dB and 61.2 dB, respectively. One feature of Alen air purifiers is that they also utilize pink noise, which is meant to be even more sleep-friendly white noise.
We know noise can be subjective, so here’s a video to allow you to hear the different noise levels associated with running the Alen Flex across each of the available fan speeds:
The cost to run an Alen Flex: $83,23 per year
This calculation assumes you will stick to OEM filter replacements from Alen.
1. Electricity costs = $25.23 per year
Even at the highest speed, the Breathsmart Flex only pulled 24.2 watts, which is MUCH LESS than many competing air purifiers with this level of air cleaning performance. This means you can leave this unit on without worrying about large energy bills.
2. Filter costs = $58.00 per year
The Breathsmart Flex uses the same filter choices we see with the Alen 45i, and on average, they are a little higher than we see from budget brands like Levoit or Taotronics. For those looking for large amounts of activated carbon, you will also have to pay a little more as these filters cost more than the Pure version.
If you don’t mind choosing non-Alen filters, you can get generic filters that cost $45.99 instead of $58 to reduce this cost a little.
Bottom line: Should you get an Alen Flex?
The perfect option for Alen fans who don’t want ionization technology and who don’t care about smart features.
The Alen Flex is the cheapest Alen air purifier sold. They can sell it at a lower cost than the Alen 45i as it lacks the ionizer and smart features. The Flex still benefits from the high level of air cleaning performance, filter options and lifetime warranty that all Alen brand air purifiers benefit from.
If you don’t mind giving up the smart and auto mode for timers, then the Alen Breathsmart Flex is an air purifier that will do an excellent job keeping small-medium-sized rooms clean. It doesn’t create too much noise and has very low energy consumption.
