Half the surveys I do in winter start with someone pointing at a window sill. Water on the glass, black speckling in the corner of the reveal, a swollen timber sill, a curtain gone mouldy at the hem. The homeowner wants to know whether the windows are failing. Mostly they are not. The glass is the coldest surface in the room, so it is where the moisture in the air shows up first.
A window vac is a squeegee with a motor. It sucks the water off the glass into a small tank, and that is all it does. It does not make the room drier, and it will not fix the cause of the condensation. What it does do is stop that water running onto the frame, soaking into a timber sill and feeding mould on the sealant, which is a real benefit. Used every morning in winter, it is a cheap, practical way of managing the symptom while you deal with the cause.
So read this as a guide to a symptom-management tool, not a cure. If the room is wet because the air is wet, a dehumidifier, a proper extractor fan, trickle vents or positive input ventilation is where the real fix sits; I have written those up separately and link them below. Here are seven cordless window vacs, compared on what matters.
The one I’d buy
Kärcher WV 2 Plus
The sensible middle of the market: a 280mm blade, a published run time of around 35 minutes, a spray bottle kit and an easy-to-empty tank, at a price that does not feel silly for something used for ten minutes each morning in winter. It is the model other window vacs get compared against, and spares and blades are easy to find.
Typically £60–£85
Check price on AmazonHow I judge a window vac
Run time against how many windows you have. Makers quote run time in minutes or in “windows per charge”, and the two are not comparable. A 25 to 35 minute vac is enough for most flats and terraces. A house with a lot of glass, or a conservatory, is where the 100 minute models earn their money. Treat any “120 windows per charge” claim cautiously.
Blade width and reach. A wide blade means fewer passes on a patio door, but it is no use in a small sash pane or a bathroom window. Two blade widths in the box, or a small separate head, solves that. Corners and the bottom edge of a pane are where cheap units leave a line of water behind, and that line is the water that runs onto the sill.
Tank size and how easily it empties. A 100ml tank fills quickly on a wet morning, and a larger tank means fewer trips to the sink. Whatever the size, the tank should lift out and empty without a fight, because a unit that is awkward to empty stays in the cupboard.
Battery: removable or sealed. A sealed battery makes the whole unit disposable when it fades. A removable one lets you buy a spare. For a tool used daily from November to March, that matters more than most spec sheets let on.
The comparison
| Product | Key spec | Typical price | Best for | |
|---|---|---|---|---|
| Kärcher WV 2 Plus | 280mm blade, ~35 min | ~£70 | Most homes with a few windows | View |
| Kärcher WV 6 Plus N | ~100 min run time | ~£105 | Large houses, big glazed areas | View |
| Kärcher WV 5 Plus N | ~35 min, removable battery | ~£120 | Heavy use, a spare battery to hand | View |
| Bosch GlassVAC | Two blade widths, ~30 min | ~£80 | Bathrooms, tiled surrounds, shower screens | View |
| Vileda WindoMatic Power | Two power modes, flexible neck | ~£50 | Flats, bathrooms, tight budgets | View |
| VonHaus Rechargeable Window Vac | ~300ml tank | ~£40 | A bathroom and a few windows on a budget | View |
| Beldray Cordless Window Vacuum (BEL0749) | No-frills, basic | ~£30 | A single bathroom or a rented flat | View |
The picks in detail
Kärcher WV 2 Plus
Best overall — and my top pick above
The WV 2 Plus is the window vac every UK review site starts with, and for good reason: it is the plain, sensible middle of Kärcher’s range. Published run time is roughly 35 minutes on a charge (some reviewers quote less), which is a whole house of ordinary windows if you only do them when they need it. It comes with a spray bottle and concentrate for the occasions you want to wash rather than just wipe, and the 280mm blade handles tiles and shower screens as well as glass. Reviewers describe it as quiet and easy to empty.
For
- Wide blade clears a pane in a few passes
- Spray bottle kit in the box
- Spares and blades easy to find
Against
- Reviewers report it struggles on angled glass and conservatory roofs
- Bulkier than the entry-level WV 1
Typically £60–£85
Check price on AmazonKärcher WV 6 Plus N
Best premium pick — for large houses and a lot of glass
The WV 6 Plus is the one for a house with a lot of glass or a conservatory. The headline is a published run time of about 100 minutes, roughly three times the WV 2, plus a quicker charger and an edge-guidance feature that helps keep the blade in a straight line off the frame. The battery is not removable, so when it eventually fades the whole unit goes, which is worth weighing against the price.
For
- Run time to do an entire house in one session
- Edge guidance helps on large panes
Against
- Non-removable battery
- Reviewers find it heavier to hold for long sessions
- Around half as much again as the WV 2
Typically £90–£120
Check price on AmazonKärcher WV 5 Plus N
Best for heavy use — removable, swappable battery
The WV 5 sits between the other two Kärcher models. Published run time is around 35 minutes, the same as the WV 2, but the battery lifts out, so a spare gives you a second charge without waiting around three hours. Reviewers also single out the smaller head attachment and quieter running. Only worth the premium if you do windows often, or have a lot of them in one go.
For
- Removable battery you can swap
- Smaller head for frames and corners
Against
- Roughly double the price of the WV 2 in review comparisons
- Charge time of around three hours
Typically £100–£140
Check price on AmazonBosch GlassVAC
Best for showers, tiles and hobs as well as glass
The GlassVAC uses wiper-blade technology borrowed from car windscreens and ships with two blade widths, which is why reviewers rate it above the others on shower screens, tiles and even kitchen hobs. Run time is around 30 minutes with an LED charge indicator. Against that, reviewers note it is slow to charge (about three hours) and does not clean right to the edges as well as the Kärcher range.
For
- Two interchangeable blade widths
- Streak-free on non-window glass surfaces
- Charge indicator
Against
- Awkward at the bottom of a window
- Slow charge
Typically £70–£90
Check price on AmazonVileda WindoMatic Power
Best value — the one for a flat or a couple of bathrooms
The WindoMatic Power is the budget pick that most often comes out well in comparisons. It has two suction modes, a flexible neck that reaches corners, and a dishwasher-safe removable tank. Vileda quotes up to 120 windows per charge; other reviewers suggest the real figure is far lower, so treat that number with caution. Reviewers also mention no microfibre cloth in the box and weaker performance on horizontal surfaces.
For
- Lowest price of the branded options
- Removable, dishwasher-safe tank
- Flexible neck for corners
Against
- Marketing run-time claim looks optimistic
- No microfibre cloth supplied
Typically £40–£60
Check price on AmazonVonHaus Rechargeable Window Vac
Best capacity for the money — larger tank
VonHaus sells a cheaper alternative with a notably larger tank, around 300ml according to one review, which matters on a patio door or a bay where the vac fills quickly. Quoted run time is shorter, about 25 minutes. Review feedback is that it copes with condensation, but splashes water if tilted and does poorly on conservatory roofs.
For
- Larger tank means fewer trips to the sink
- Cheaper than the Kärcher models
Against
- Reviewers report water splashing
- Not suited to conservatory roofs
Typically £30–£55
Check price on AmazonBeldray Cordless Window Vacuum (BEL0749)
Cheapest overall — use with realistic expectations
The cheapest unit here and the simplest: switch on, squeegee, empty. Reviews describe it as no-frills and easy to empty. The recurring caution is durability, with some owners reporting problems after a few months. Fine if you only want something to take the morning water off one bathroom window; I would not choose it for a house that gets wiped daily all winter.
For
- Lowest price of the seven
- Simple to use and empty
Against
- Durability complaints in owner feedback
- Fewer accessories
Typically £25–£40
Check price on AmazonWhat actually matters — and what doesn’t
A window vac is only half of the answer. The other half is the moisture in the room. Humidity sitting above about 60 per cent, laundry drying indoors, showers with no extractor will all produce wet glass however well you wipe it. A cheap hygrometer tells you where you stand, and a CO2 monitor tells you whether the room is being ventilated at all.
Wipe the sill and the seal, not just the glass. The vac gets the water off the pane. The black mould I see is almost always on the silicone seal at the bottom corner and on the timber or painted sill beneath it. Take the vac along the bottom edge and run a cloth over the sill. Water that sits there for a week is the problem.
When the real fix is something else. If the glass is wet every morning, the fixes are ventilation (an extractor fan, trickle vents or a PIV unit), removing the moisture source (a heated airer rather than laundry draped on radiators) and, in a very damp house, a dehumidifier. Tired single glazing or failed sealed units are a different issue and cost real money; the double glazing cost guide covers that. Thermal curtains can make condensation worse if the room is not ventilated, which I cover in the thermal curtains guide.
What the box pushes that does not matter. Run-time headlines in “windows per charge”, the number of accessories and the cleaning concentrate. Water and a squeegee blade do the job. Check the blade is replaceable and the tank empties easily, and ignore the rest.
Questions I get asked
Do window vacs actually stop condensation? No. They remove the water that has already formed on the glass. The condensation comes back the next night unless the humidity in the room comes down. They are a good way of limiting damage while you fix the cause.
Are they worth it if I only have a few windows? Often yes, if the condensation is a daily winter occurrence. The alternative is ten minutes with a cloth every morning, and a cloth tends to leave the water on the sill. If it is a one-off, a squeegee will do.
Can I use one on moisture between double-glazed panes? No. Water between the panes means the seal has failed. No window vac will clear that, and the sealed unit needs replacing. A surveyor will note it as a defect.
Will a window vac get rid of black mould on the sill? No. It stops the water that feeds it. Existing mould needs treating separately, and persistent mould on a window reveal is often the first sign of a wider ventilation problem.
If the glass is wet every winter and you want to know why, that is a job for an assessment rather than another gadget: a ventilation assessment or a building survey will tell you whether it is the air, the glazing or the house. Get in touch if you would like one done properly. For the rest of the kit, there are more field-kit guides.
Small print. This guide is general information, not an inspection of your property, and a window vac does not treat the underlying cause of condensation or damp. Prices are indicative, move constantly and are checked at the time of writing; the linked page always shows the current price. As an Amazon Associate I earn from qualifying purchases.