Thought I would pass on a piece of information that is relevant to the use of Thermal stores and modulating condensing boilers, which may be of use to others.
In 'normal' systems without a thermal store, modulating boilers would be ideal, although they would be required to fire up regularly due to the fact that there is no energy buffer present
With modulating system boilers which modulate the flow rate to maintain an ideal "Delta T", when used with thermal stores a problem arises with the production of domestic hotwater, in that the modulating reduces the heat coming into the store when you need it under heavy loads.
The stored boiler water should really flow at a constant flow through the heat exchanger in order that domestic hot water production be maintained under heavy load situations.
With thermal stores it's better to go for a condensing, non modulating boiler.
I have a Baxi Barcelona, and this by default is a 70,000 btu/h boiler, to convert to maximum output of 80,000 btu/h you need to remove bridge No.2 on the control pcb.
To turn off the modulation and have maximum output remove all 3 bridges on the pcb.
The same applies to the 100HE
Rick