I have A CH system with gravity HW with a mechanical cylinder stat. and the heating controlled by a 2 wire mechanical thermostat.
The Controller is mounted near boiler which is not easily accesible.
Gas fired boiler replaced in past 3 years.

Wanted to both change the thermostat to a digital one to get more accuracy and at the same time introduce more flexibility into the system to replace existing controller which is of the conventional HW or HW+CH "auto" "twice daily""continuous" type

Thought the anwer would be to get a wireless programmable digital thermostat but on reading all the installation instructions vial downloads none of them appear to be able to send a signal to just have HW on like in the summer time for example. In my case it would just mean a signal to activate the boiler to "on" as the HW would then be heated.
I do not have a problem with the upstairs rads getting hot as these are all fitted with thermo valves.

Anyone any idea how to arrange this, my thoughts are leaning to the 2 zone type receivers and using the second zone as the hot water on but think this may still end up calling the pump.

There must be a lot of CH systems like mine and I cannot understand why the makers of the wireless programmers have not addressed this HW problem.

Grateful for any ideas from anyone.