Money Saving Boiler Challenge and Thermal Store systems

Bendo

Bit of a later reply, but do you use the timer at all? 

I find mine (same store but with a glowworm non condensing boiler) uses about 7KW of gas a day to keep the store hot,  in the summer when the heating isn't required,  I set the timer so it only heats up for an hour or so in the morning and the hot water normally lasts for the day.  This reduces the gas consumption down to about 3KW.

P.s. even set to max, the boiler may still be condensing as they layer the water and its colder at the bottom where the return is.