Before we review any new category, in this case, window cleaning robots, we need to figure out the paradigms to test and judge against.
We put our consumer panel to the task, and here is what they came up with.
Window cleaning robots – what to look for
There appear to be two main shapes of window cleaning robots (Winbots).
The square style with a microfibre pad ‘drags’ over the glass (not unlike a flat plate-style robomop).
The round rotating pad has two microfibre pads that usually rotate in counter directions (not unlike a dual-head robomop).
We will address how these stick to the glass later (vacuum or magnet).
The highest on the expectation list was effectiveness
Meaning 100% coverage and streak-free cleaning. But that is perhaps the hardest to achieve, although some can come close.
As we found with the dual-head Hobot 388, it takes a ‘dry’ pass first to remove dust and grime, followed by a ‘wet’ pass second to clean and polish the glass.
We presume this is similar to a dual (not single) pass platen style robomop.
Winner – dual-pass does a better job
Flat pad or rotating pad
As we found with robomops, the critical issue here is to change microfibre pads frequently to avoid dirty pads leaving streaks on the glass.
Our experience with the dual counter-rotating Hobot 388 is about 15m2 of wet cleaning before you change pads.
We can only assume fixed flat pads will need more frequent changes as the leading edge tends to do all the work and gets dirty faster.
Winner: Dual rotating pads appear better and offer some ‘elbow’ grease. We are not aware of the effects of any vibrating pad yet.
Water or Window cleaner
Don’t skimp on a good window cleaner recommended by the Winbot maker. Water is only 40% effective at removing salt spray and environmental grime. A good windows cleaner has cutting power and will remove this type of scum.
Volume of water or cleaner
We only have experience with the Hobot 388 that uses a 15um nano-spray to wet a portion of the window below the bottom pad. It does not leave water marks or streaks as there is not enough volume.
Some Winbots have centre wetting vents to wet the pads that appear to use a lot more liquid. Less is best.
But also remember that fine spray is subject to the wind blowing it off course. Clean on a still day.
Winner: nano-spray spray over wetting.
100% coverage – not going to happen
The square type often has triangle cuts at the four edge points, meaning that it cannot clean corners.
The twin round rotation pad also can not reach corners
Winner – Draw
Vacuum or magnets
Vacuum style creates a vacuum to adhere to glass. These invariably come with a safety rope to stop death dives. Safety ropes are a great idea but not always convenient.
The Hobot 388 takes a slightly different track – it is mains powered, and the onboard battery acts as an uninterruptable power supply (UPS) to give 20 minutes of vacuum adherence in case of a power failure.
Magnet mounts are safer in that you place a rubberised magnetic pad on the opposite side of the glass, and the magnets hold the device in place. But there are a few downsides. You may not be easily able to access the other side of the glass, and magnets strong enough to go through thick glass, are heavy. They do not work on thicker glass, are not good on curved glass, and the magnet pad can scratch the glass.
And avoid those with tractor wheels (generally magnetic type) as the wheels can leave wheel marks if wet.
Neither can handle negative slopes (like inside sloping skylights) over about 45° as the weight and slip factor vectors cross over, leading to the death dive.
Winner: Vacuum suction
These are to prevent a plunge to death after sudden detachment. As far as we know, no Winbot could withstand a few metre fall without breaking something.
The real question is where to attach the safety rope, especially in indoor windows when there is only a ceiling overhead.
The answer will only come from experience and confidence with your Winbot. If it has had no death wish issues, perhaps trust it. But why not place a soft pillow at the window’s base to break its fall.
Run time and clean time
The panel said that Winbots should be faster than doing it yourself with a squeegee.
The Hobot 388 takes about 4 minutes per 1m2, and you have two sides and two passes (dry and wet). It also has mains power via a 5m lead to provide adequate amperage to the vacuum engine. The battery is small and light, acting as a safeguard against the loss of mains power. This means it can clean all day without a charging break.
But if you use an AC extension cord, remember that all Winbot can only carry their weight and a few metres of a lightweight DC power cable and safety rope. They cannot hold an AC cord weight, especially if it is lifting it off at an angle to the ground.
If you have a battery-operated only unit, expect it to be heavier with relatively short runtimes and long charge times.
We have no experience with other brands, but 4-minutes per m2 seems reasonable. But to get the best, you need two passes, which means it is a lot slower than you think.
Winner: mains power
By definition, a robot (be it a vacuum, mop, lawnmower etc.) should be able to be left unattended to do its job. In our experience, no amount of AI or clever navigation means you can leave a robot anything unattended.
In this case, after every window pass, you need to turn it off, remove the safety rope, move it to the next window and repeat. So no, regardless of types, they all have this issue. Your peaceful time doing other things will suffer regular interruptions.
Winner: Draw, but faster clean times are better
AI versus pattern cleaning
Most Winbots boast AI, but in reality, it is simple pattern cleaning. Please at the top or bottom window corner and let it logically clean in a u-pattern as it ascends or descends the glass. Odd shaped glass should not worry these as most use the frame edge and the trigger to change direction. Frameless glass needs AI detection. But remember that it cannot clean in corners, so you may have to do that manually.
We found it was best to place the Hobot 388 at the top of the glass as it meant the top rotating pad stayed dry to polish with the wet work on the bottom pad.
But AI in the form of sensors is worth spending more on. For example, the Hobot 388 has a vacuum variance sensor that detects frameless glass edges and can work on frameless mirrors and even tiles.
AI will generally have a Bluetooth app. Our experience is that the app adds little to no functional value and could have privacy issues. Often fake reviews point out the lack of a scheduling feature – they have obviously never used one as you really need to be around to monitor and move them.
Some also have remote controls – that can be handy.
Winner: Most should have an automated cleaning pattern, but it may be best to look at one that can do a little more.
Some vacuum models can break the thinner 3mm glass. Thicker glass can impact magnetic models. Standard 4-10mm glass is fine.
Winner: Lighter devices are better for thin glass
Flyscreens and dreaded security screens
If you have them, you must remove them before cleaning that window surface. Most flyscreens have twist clips, but some slip into window frames, and some use magnets. If your home is older, then plan on breaking a few clips.
And if you have permanently affixed security screens the only way to clean the window is to remove it. Sliders should simply lift out.
But as cheap as clips are, older screens may have more issues like perished rubber splines, brittle mesh (over time, it becomes hard and breaks easily) or pitted aluminium frames. Whatever you do, be prepared to rip down to Bunnings to get a flyscreen repair kit.
Handles, window winders, hinges, locks and more obstructions
Take care if anything protrudes into the glass area. Most bots will get stuck (except those with some AI to recognise this).
Winner: See if AI handles this
Vacuum Winbots make a noise. The Hobot is 70dB at 1m, and that is fine. We have not tested magnetic Winbots, but we assume that they would be quieter.
All need dry glass, meaning no rain, snow or high humidity. Don’t use it on windy or overly hot days.
Look for models with replaceable water tanks, flat plates, pads, and above all, the sprayer nozzle. Most will have washable microfibre pads.
Winner: Look at better-known brands
Most should have no issues on vertical framed or frameless glass, shower screens, tiles etc. But remember that the window cleaner solution probably will not cut through soap, shampoo and conditioner scum. As a rule, if you can easily remove the scum with a damp cloth and the window cleaner, it will work.
Finally, are Window cleaning robots worth the cost?
The answer is, how much do you hate windows cleaning? And second, every type of Winbot will have strengths and weaknesses. How much are you prepared to live with these?
If you are happy that the issues identified above don’t cause you problems, it is a good investment. Note that Winbots are consumer standard. If you have a business with large glass areas, you should invest in commercial quality and safety warning barriers.
The Hobot 388 (review here and website here ) costs $540 (even less on promo) with a low-cost window cleaner solution and pad consumables. In our opinion, it is damned good – but it is the first we have tested in this category. Images courtesy of RobotMyLife.