Basically it looks to me like a mismatch of components that aren't really compatible. I'll try to explain how I came to this conclusion.
The diagram you posted is for a different installation to yours. That diagram has a single channel programmer for the hot water and 2 x
programmable room thermostats, which is why the link between L & CH1 is required to permanently power the thermostats. Programmable thermostats include both time and temperature control in one unit, so there is no requirement for separate heating time control. Meaning....
1. If you have a
programmable room thermostat that does have time and temperature control built in, ie you can set a different room temperature at different times, then how you describe it working, is correct and the CH channel of the programmer shouldn't be doing anything. [Ideally a single channel programmer just for the hot water should have been fitted, (as per the diagram) and not the dual channel programmer with CH control that you have]
2. If your thermostat isn't programmable, then to allow the CH of the programmer to control the heating on/off times, the link shouldn't be present and the circuit board CH1 terminal should only be connected to the programmer's terminal 4. However, if it isn't programmable, there may be a further complication. It appears that you have a wireless room stat receiver (as per your photo below) which does need a
permanent mains supply....
.....and so shouldn't be switched off by the programmer. If this is the case and your thermostat isn't programmable, then:
1. Either the thermostat / receiver needs changing for one that doesn't need a permanent 230V supply, or
2. An additional wire to provide a permanent live supply to the receiver is required, or
3. Get a programmable room thermostat
Hope you can make sense of my ramblings
![Confused :confused: :confused:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)