C2E621201_GY_C1 Schneider Cuadro H Grey Heating Cooling Controller KNX Setpoint Screen HVAC Fan Coil

The grey version of the Cuadro H thermostat exists for a reason that has nothing to do with the electronics: on a wall painted in light grey or off-white, a white plate reads as a patch and a grey plate disappears. The C2E621201_GY_C1 is otherwise the same room controller as the rest of the family — a KNX bus device with a colour touch screen, an internal temperature sensor and no mains terminal, drawing approximately 19 milliamperes at 24 volts from the line and commanding fan coil units, underfloor loops and fresh air units through group addresses.

The functional argument for the product is that it puts the measurement and the control in the same place: the sensor is in the plate, the setpoint is changed on the plate, and the screen shows the measured temperature and whether the system is heating or cooling, so an occupant can see a discrepancy instead of guessing at it.

Grey is also the finish where the instructions about proximity sensing deserve a second reading, because the documentation states that the sensing range of about 12 centimetres varies with the ambient brightness and with the colour of the product. A grey plate in a dim corridor is therefore a different sensor from a white plate in a bright one, and the wake-up function should be checked in the finished room rather than assumed from a datasheet.

The siting rules are strict for the same underlying reason, since the sensor measures the air where the plate hangs:

• Nothing within 30 centimetres in front of the plate.
• Nothing within 3 centimetres below the plate.
• No direct sun exposure.
• No position beside a radiator, a supply diffuser or an air conditioning outlet.

In a hotel room the plate normally goes beside the door at switch height with a clear approach. In a cellular office it goes on the internal wall away from the window wall, rather than on the glazed facade where solar gain would corrupt the reading.

Grey thermostats are specified where the interior is a warm neutral rather than pure white. Hotel guest rooms with greige joinery and stone bathrooms use them because the plate sits between a grey door frame and a grey wardrobe, and the white version would stand out. Serviced apartments and residential bedrooms apply them where the wall is painted in a light grey and the client has deliberately avoided pure white plastics. Clinics and consulting rooms use them where the wall finish is a washable light grey and a white plate would yellow under the cleaning regime. Offices with grey fabric partitions specify them for the meeting rooms, where the thermostat sits next to a grey keypad and the two are expected to look like one installation rather than two purchases.