Boiler recommendations please?

John Rumm was thinking very hard :

Thanks, you are correct - but I wonder why their help desk didn't point me in that direction?

If you pair it with conventional controls, then it won't be able to work out what function its supposed to be doing - so then it will use the CH flow set point temp all the time.

I presume the boiler gets 2 separate call for heat signals, I don't remember.

NT

Ideally it has a NTC probe connected to the cylinder, and a "smart" wiring centre that is connected to the boiler via eBus to allow it to control the zone valves (Y or S/S+ only I would guess).

Then it can work out what to do based on the program set on its programmer (i.e. what times of day the DHW can be recharged), and the input from the sensor giving the current cylinder temp. Then it will set the valves for DHW only heating, and run appropriate flow temperatures for the DHW reheat.

(the boiler can also control a secondary circulation pump and a recharge pump as well if required)

It seems smart enough to not try and run both CH and DHW at the same time (therefore avoiding running the rads at DHW temperatures), even if the programs are overlapped. I did not realise it would do that at first and programmed them to run at different times. These days I tend to have DHW "on" for quite long periods shared with the heating, and that allows it to work out when there is a big demand for hot water and switch to reheating faster so you get more apparent hot water capacity from the cylinder.