Ecovacs Winbot 920 · HUTT DDC55

Simple to operate, fixed in what it does: the pad sequence and spray volume are the same on lightly dusted glass as on mineral-etched glass, so heavy soiling takes a second run rather than a longer first one.

Entry-level cost buys fundamentals rather than features: the DDC55 holds the glass with a suction range HUTT states as 2000 to 3800 Pa and cleans with twin rotating discs, but it is a corded, remote-controlled machine with no app, no schedule and no mapping, and each pane is started by hand.

Windows out of reach of an indoor socket

Ecovacs requires the plug and power adapter to be used indoors, and the power cable is short, on the order of four meters per Ecovacs distributor listings. That puts the working envelope at about one room's reach of an inside outlet. There is no configuration of this robot that runs from an outdoor socket.

Frameless glazing, or exterior work in wind or at elevation

Ecovacs sets three hard limits: a window frame of at least 5 mm, which effectively rules out frameless glass on this generation; no operation in whole gale storms or force-10 winds; and no use above 2,000 m (6,162 ft) of altitude, where thinner air weakens the suction seal.

Heavily soiled or mineral-etched glass

Spray volume is fixed rather than varied by soil level, so etched or heavily deposited glass needs pre-soaking or a repeat run rather than a longer single pass.

Owners wanting cordless operation

The 920 is mains-fed with the adapter indoors, so the cord has to be routed to each window. App control is not what separates it from newer models: the 920 is Ecovacs' first app-controlled window cleaner and pairs with ECOVACS HOME over Bluetooth. What later models add is running without a cord.

Windows with no immovable anchor point for the safety rope

HUTT's procedure requires the safety rope's locking ring to be fixed to a solid object that cannot be dragged, and requires the rope to be checked before every run for secure attachment and damage. Where a window offers no such anchor within reach, the machine should not be run on it.

Hard-water areas or homes with frequently soiled panes

The cloths are wetted by hand before a run and the machine carries no water of its own, so mineral deposits and heavy pollen mean pre-treating the pane and changing the cloth part way through.

Owners needing app control, scheduling or mapping

The DDC55 is driven from a handheld remote. There is no network connection, no app and no schedule, and the machine has to be placed on each pane by hand before it will run.