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Portable air purifier

Alen BreatheSmart 45i

US BreatheSmart 45i

$449US price, checked Oct 13, 2026

Slim, quiet HEPA purifier with a guarantee tied to Alen filters

Check price at Alen Full review →

Portable air purifier

Winix 5500-2

US 5510, the closest current model to the discontinued 5500-2

$199.99US price, checked Oct 13, 2026

Discontinued, with the 5510 as the closest current model for rooms near 390 ft²

Check price at Winix Full review →

Criterion	Alen BreatheSmart 45i	Winix 5500-2
US price	$449Checked Oct 13, 2026 · Price details in the review	$199.99Checked Oct 13, 2026 · Price details in the review
Three-year ownership estimate	$725 Incomplete known subtotal. Not included: energy use.	$349.96 Incomplete known subtotal. Not included: energy use.
Choose if	You want a quiet, slim HEPA purifier for one large room and don't mind buying Alen filters every year.	A bedroom or living room up to about 390 ft² where you want app control and one filter change a year.
Main trade-off	Filters add $69 to $198 a year, and Alen gives its own airflow figure instead of AHAM smoke, dust and pollen ratings.	It isn't in ENERGY STAR's certified list, and Winix's AHAM and CARB claims couldn't be checked in either registry.
Key specifications	Clean air delivery rate: 255 CFM on high by Alen's own CADRi figure; 80, 120 and 190 CFM on the lower speeds. No separate smoke, dust or pollen CADR on Alen's page. Room size: 950 sq ft at 2 air changes an hour or 1,900 sq ft at 1, by Alen's figures. Its FAQ says up to 1,600 sq ft. Noise: 24 dB on the lowest speed to 50 dB on high Power draw: 1.6 to 64 W in the spec table; the FAQ says 50 W on high. Alen doesn't say which setting draws 1.6 W. Filter life: Essential (Pure) 9 to 12 months; Advanced (Fresh) and Ultimate (Odor) 6 to 8 months, running 24/7 Filter price: $69, $89 or $99 each; 10% off on subscription ($62.10, $80.10 or $89.10) Ozone: Optional ionizer: under 0.001 ppm when on, 0 ppm when off. Alen lists CARB certification.	CADR (smoke, dust, pollen): 253, 252 and 247 Room size: 392 ft² at 4.8 air changes an hour (8 ft ceilings). Winix also says it cleans 941 ft² in 30 minutes and 1,882 ft² in an hour Noise: 23.5 dB on the slowest speed. No figure for higher speeds Power draw: 65 W rated. No figures for each speed or standby Filters: Washable fine mesh pre-filter, AOC carbon filter and True HEPA filter, plus PlasmaWave you can switch off Filter life and price: HEPA and carbon 12 months each. A Filter Q set is $49.99 on sale ($79.99 regular) Controls: 5 fan speeds (Low to Turbo, plus a slower Sleep speed), auto mode, light-sensing sleep mode, filter light, WiFi and Alexa. The timer is only in the Winix Smart App Size and weight: 13.59 × 8.27 × 22.17 in; 13.3 lb
Exact variant	US BreatheSmart 45i	US 5510, the closest current model to the discontinued 5500-2
Dimensions	25 in high, 15 in wide and 8.5 in deep, and 14 lb, according to the product page. Alen's support table lists the 45i/FLEX at 19 × 11 × 28 in and 23 lb. That's the same size it gives for the shipping box.	13.59 × 8.27 × 22.17 in (width × depth × height). It weighs 13.3 lb. The 5500-2 was wider, taller and heavier, at 15 × 8.2 × 23.6 in and 15 lb.
Installation	Freestanding, with no installation. It runs from a 24 V external power adapter. The manual asks for a level surface at least 6 in from heat sources such as heaters, with the vents left clear. The Alen Air app adds remote control, scheduling and filter alerts over Wi-Fi.	No installation. It plugs into a standard 120 V, 60 Hz outlet. Winix's manual says to leave 12 to 18 in from walls, and never less than 12 in while it runs. Leave the same gap from TVs, radios and other electronics. Use it indoors on a hard, flat surface, out of direct sunlight.
Materials	One filter cartridge with a prefilter you can vacuum. Essential (Pure) is a True HEPA (H13) filter aimed at dust, pollen, dander, mold and allergens. Advanced (Fresh) adds activated carbon for VOCs, smoke and cooking odors. Ultimate (Odor) adds an odor neutralizer for pet and diaper smells. An optional ionizer can be turned on or off. The front panel comes in White, Oak, Weathered Gray, Brushed Stainless, Graphite or Espresso.	Four stages: a washable fine mesh pre-filter, an AOC carbon filter made of carbon pellets, a True HEPA filter and PlasmaWave. Winix says the HEPA filter was tested to IEST-RP-CC0007. The manual says the carbon filter can't be washed. Housing materials aren't stated. It's made in Korea.
Warranty	Alen gives a 1-year manufacturer's warranty. Its Forever Guarantee extends that if you register the serial number and use only Alen filters. You also need an active filter subscription or proof of an Alen filter purchase in the last 12 months. If troubleshooting can't fix a fault, you get a new unit in year two. From year three you get a refurbished or reconditioned unit, and the guarantee page sets no end date. Alen's support page says to register within 12 months of purchase. The guarantee doesn't transfer and excludes accidental damage, floods and fires. The product page says it needs an active subscription, but the guarantee page also accepts a recent filter purchase.	Winix gives the 5510 and 5520 a 2-year limited warranty, valid only in the US and Canada. If a part is defective, Winix will repair or replace the part or the unit. You need proof of purchase from an authorized retailer. Independent sellers on Amazon, eBay and similar sites don't count. Non-Winix filters void it, and the filters themselves aren't covered. Claims start with a form in your winixamerica.com account, and you may pay for spare parts or shipping. The manual lists repair services as not available and says no spare parts will be made after the warranty ends. The discontinued 5500-2 is still on Winix's 2-year list.
Returns	60-day trial on orders from alen.com. Alen refunds the purchase but deducts return shipping, using a FedEx label it emails you. Opened filters can't be returned. The refund can take up to 7 business days after the warehouse receives the return. Orders from other retailers go back through that retailer. Alen doesn't say whether the 60 days start at purchase or delivery.	Orders from winixamerica.com can be returned within 30 days of purchase. Returns must be in the original packaging with all filters, manuals and parts. You pay the return shipping, and Winix asks you to mark the return authorization number on the box. If you bought from another retailer, its policy applies. Restocking fees aren't mentioned.
Unresolved questions	Smoke, dust and pollen CADR from AHAM or Energy Star testing Whether CARB's own list includes the 45i (Alen's linked order file has no readable text) Average power on auto, so the yearly electricity cost Whether the store ships the original 45i or the touch-control 45i V2 named in Alen's CARB and Energy Star files The true size and weight, since Alen's product page and support table disagree How long a filter lasts if you don't run it around the clock How often subscription filters ship	Power draw at each fan speed and on standby, and which speed the 65 W rating refers to Noise on Low, Medium, High and Turbo Whether AHAM's directory lists the 5510 at Winix's CADR figures. The directory couldn't be read Whether CARB certified the 5510 or 5520. The readable part of CARB's list showed only the 5530 Whether PlasmaWave is on when you first switch the 5510 on. The 5500-2 manual says it was Whether there's any timer without the app Shipping cost from Winix's store How long the $199.99 and $49.99 sale prices last How the 5510 does in independent testing

These comparisons use published specifications, not head-to-head tests. Prices and terms are dated. Unknown costs are not zero. Check the exact variant before you buy.