Do thermal stores have the DHW coil mounted high up in the cylinder, nearly right at the top?.
If so, and assuming a 300 litre store at 75C and if you draw off 100 litres of HW at 40C from cold at 6C do the whole contents of the store then fall, to 64C?. (63.8)
If so, and assuming a 300 litre store at 75C and if you draw off 100 litres of HW at 40C from cold at 6C do the whole contents of the store then fall, to 64C?. (63.8)