Non aviation content. Play nice – No religion, no politics and no axe grinding please.
I currently have an ageing Drayton LP722 programmer; it is designed to control CH & HW, but I have bodged it to control two HW tanks independently (& no CH) instead. It is losing time badly (hours a day), but I can't find a replaceable battery or why this is happening.

Ideally I'd like to change it to a smart programmer. Does anyone know of something that could do this? Would prefer not Hive or Nest (as I already use these elsewhere & don't want to keep signing in/out). Would any two channel smart system work in this scenario, or do I need to look for something more specific?

All I need is to be able to independently turn on/off two tanks once a day.

It's pretty easy; I tend to favour the Hive products. The issue you will have is that a 2 channel Hive controller has 1 hot water circuit, and 1 central heating circuit. The latter could be used to control a second cylinder, however the room thermostat is built into the display module, so could potentially shut off the hot water cylinder it was controlling when a set room temperature was achieved. This could be avoided simply by setting the demand temperature to a silly figure (or keeping the display in the fridge). If wired with the existing cylinder thermostat interrupting the switched live supply to the relevant zone valve, you would still retain hot water temperature control as you have now. If you need 3 zones, to include a radiator or UFH circuit, you'd need one 2 channel unit plus an additional zone pack.

Feel free to send me a PM if you want a chat.

Big Dex.... Gas Safe registered heating chap.