The way the product works is that it has a target temperature it will turn on and off based around. To prevent the device switching on and off too regularly, there is a 1C threshold before the flame is shown and the boiler is told to switch on or off. This will mean that if you are targetting say 20C, then the device will only switch on and off when it goes below 19.5C or above 20.5C.
Would this explain the performance you've had with the Thermostats at all?
It’s 0.5C above/below the set point - a 1C threshold in total
The thermostat can only have one setback temperature for each day (6am to 6am). This setback temperature means that the heating will be turned on should the temperature ever fall below it. The thermostat can then have up to 5 ‘on’ schedules a day.
The device is set up to target an average temperature of what you choose, with it switching on and off half a degree above or below the target you choose. This is the programmed behaviour of the thermostat and is not able to be adjusted. You should see the flame symbol appear and clear away when the heating is switched on and off.
During these schedules the thermostat will target a temperature above the setback for the period set. It isn’t possible to satisfy your request exactly, but we’d suggest that, during the week, set a setback of 18 degrees and then two on periods of 7am to 10am and 6pm to 11pm where a target of 22 degrees is set. This will mean that the heating will not be allowed to fall below 18 at any time, and will heat the building to 22 degrees between 7am to 10am and 6pm to 11pm.
Alternatively, you could set a setback of 0 degrees (although we would suggest this being at least 5 degrees in order to avoid the potential of frost damage to the site) and then a target of 18 degrees during the two ‘on’ periods. This would mean that the heating is only on during the on periods in order to keep the temperature above 18 degrees. Rather than a temperature range, the thermostat targets a specific temperature to maintain, when the temperature moves 0.5 degrees beyond this the thermostat will turn the heating on/off. During the weekends, we’d suggest setting a setback of 5 degrees. The thermostat requires at least one schedule change of some sort each day, so an ‘on’ period of 7 degrees at some time would suffice.
There are systems out there in the market that would operate this way, however ours is just different.