Description
Cordless Cleaning That Empties Itself
Take one of the most annoying jobs out of cordless vacuuming with the Shark Clean & Empty Cordless Vacuum BU3521UK.
Once you've finished cleaning, simply return the vacuum to its dock. Shark's Auto-Empty System automatically removes the collected dirt and debris from the vacuum's dust cup, transferring it into the larger sealed base.
The base can hold up to 30 days of dirt and debris, meaning you don't have to manually empty the vacuum after every clean.
For busy households, pet owners or anyone who simply wants a lower-maintenance cordless vacuum, it's a very useful upgrade over a conventional stick cleaner.
Automatically Empties After Every Clean
The main reason to choose the BU3521UK is convenience.
Return the vacuum to its Auto-Empty dock after cleaning and the system automatically transfers debris from the handheld dust cup into the 1.3L bagless base.
Instead of carrying a full dust cup to the bin after every cleaning session, you can simply dock the vacuum and let the system take care of it.
Holds Up to 30 Days of Dirt & Debris
The larger Auto-Empty base is designed to hold up to 30 days' worth of collected dirt and debris.
That makes the Shark Clean & Empty particularly appealing if you vacuum frequently but don't want the hassle of constantly emptying a small cordless dust container.
Seals Away Dust & Allergens
Emptying a conventional vacuum can send fine dust back into the air.
Shark's Auto-Empty base features an Anti-Allergen Complete Seal, designed to capture and trap up to 99.9% of dust, allergens and irritants inside the base.
It's another reason the self-emptying system is about more than convenience — it also reduces the need to handle collected dust directly.
FloorDetect Technology
Move from hard flooring to carpet without constantly changing settings.
The BU3521UK uses FloorDetect technology, allowing the brush-roll to respond to changes in floor surface and automatically optimise cleaning as you move around your home.
Anti Hair Wrap Plus
Long hair and pet hair can quickly become tangled around a conventional vacuum brush-roll.
Shark's Anti Hair Wrap Plus technology actively separates and removes long, short and pet hair from the brush-roll as you clean, helping reduce tangles and maintenance.
That makes the BU3521UK particularly useful in homes with pets or family members with long hair.
Up to 40 Minutes Runtime
Enjoy up to 40 minutes of cordless cleaning from the rechargeable battery, giving you the freedom to move around your home without switching plug sockets or dragging a cable behind you.
Once you're finished, returning the vacuum to its Auto-Empty dock also begins the charging process, so it's ready for your next clean.
Lightweight & Manoeuvrable
At approximately 2.7kg, the vacuum itself is designed to remain lightweight and easy to manoeuvre.
Shark states that it's 30% lighter than the IZ300UK, helping make everyday floor cleaning, stairs and above-floor jobs easier to manage.
Perfect for Pet-Friendly Homes
The BU3521UK also includes a Pet Multi-Tool, allowing you to move beyond floor cleaning and tackle embedded pet hair on furniture and upholstery.
Combined with Anti Hair Wrap Plus and the sealed Auto-Empty system, that makes this model particularly well suited to homes with cats and dogs.
Key Features
- Hands-free Auto-Empty System
- Base holds up to 30 days of dirt and debris
- Large 1.3L Auto-Empty base
- Up to 40 minutes runtime
- FloorDetect automatic floor adjustment
- Anti Hair Wrap Plus technology
- PowerFins floorhead
- Anti-Allergen Complete Seal
- Captures and traps up to 99.9% of dust and allergens in the base
- Automatically charges when docked
- Quiet Mode allows charging without automatic emptying
- Suitable for carpets and hard floors
- Pet Multi-Tool included
- Duster Crevice Tool included
- Approx. 2.7kg vacuum weight
- 5-year Shark guarantee when registered; 2 years for the battery
Who Is the Shark BU3521UK Best For?
I'd position this as an excellent choice for someone who wants cordless convenience with less maintenance.
It's particularly appealing for:
- Busy households that vacuum frequently
- Pet owners dealing with regular hair and fur
- People who dislike manually emptying a cordless vacuum after every use
- Homes with a mixture of carpets and hard floors
- Anyone who wants their vacuum stored, charged and emptied in one place
You're not primarily paying for dramatically longer runtime or a huge specification number here. You're paying for convenience.
That's what distinguishes this model from something like the Dreame R20 we just did.
What's in the Box?
- Shark BU3521UK cordless vacuum main unit
- Rechargeable battery
- Auto-Empty dust cup
- Straight wand with storage clip
- Compact PowerFins floor nozzle with FloorDetect
- 1.3L Auto-Empty dock
- 8" Duster Crevice Tool
- Pet Multi-Tool
Technical Specifications
| Specification | Shark BU3521UK |
|---|---|
| Type | Cordless Stick Vacuum |
| Auto Empty | Yes |
| Auto-Empty Base | 1.3L |
| Dirt Storage | Up to 30 days |
| Maximum Runtime | Up to 40 minutes |
| Vacuum Dust Cup | 0.42L |
| Charging Time | Approx. 4.5 hours |
| Floor Detection | Yes |
| Anti Hair Wrap Plus | Yes |
| Pet Tool | Yes |
| Vacuum Weight | Approx. 2.7kg |
| Colour | White / Blue |
| Guarantee | 5 years* |
| Battery Guarantee | 2 years* |
*Subject to Shark registration and applicable UK/ROI guarantee terms.
🇮🇪 What Customers Say
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