Wifi and 4G programmable thermostat: pairing and calibration

Why the setpoint and what you feel never quite match

A thermostat measures the air temperature at the exact spot where it is fixed. What you feel also depends on the temperature of the surfaces around you, and the two can differ by several degrees. With radiant heating the gap is wider still: walls and floor rise in temperature while the air barely moves.

What calibration corrects

Calibration does not improve the accuracy of the sensor, it shifts its zero. Its job is to make the number on the display match what you want in the room, given where the unit happens to be fixed. A thermostat near a door reads too cold, a thermostat above a cabinet reads too warm.

The method

Put a reference thermometer in the middle of the room, at seated height, and let the temperature settle for several hours. Then compare the two readings and apply the difference as an offset. The adjustment is made with the unit off, holding the SET key until the A1 function appears, then using the arrows.

Pairing with the Smart RM app is set out on the page about linking to a phone. The principle of radiant heating and how it is controlled are explained on the heated ceiling operating principle page.

A setting you do not redo every year

Once the offset is entered, it holds as long as the thermostat stays where it is and the room keeps the same use. It is worth revisiting after insulation work, after a window has been replaced, or if a room that used to be unoccupied becomes an office.