You only need a thermal store if you have solar/wood burner/GSHP etc
This is clear twaddle. They are suitable for normal usages with condensing boilers. It is amazing. A number of posters confirmed that thermal stores do not sludge up when properly designed and installed. Yet these jobbing cowboys and the uninformed persists in believing misinformation against all evidence. The dissenters do not even know the advantages of thermal stores. Some are.....
a) They make the boiler run in perfect high efficiency conditions. The boiler demand is decoupled from the variable heating and DHW demands. The boiler only runs for one long efficient burn. Condensing boilers are ideally suited to thermal storage as when using a plate heat exchanger for hot water the water return to the bottom of the cylinder can be 20-25C. This is then pumped into the boiler's return pipe to promote high efficiency.
b) The heating loops using an auto modulating pump can draw off into the loop less than a kilowatt and no boiler cycling that would occur in a directly heated heating loop. And no centralized wall thermostat.
c) The radiator loops needs no temperature dropping valves. It is best the rads are taken off a simple coil in the cylinder to eliminate sludge build up in the cylinder.
d) An UFH heating loop would need a temperature dropping valve, but most of the time it will be trimming off as the temperatures in the bottom part of the cylinder is cool.
e) The hot water plate heat exchanger can ensure high hot water deliveries and be cheaply and easily upgraded to a larger version later if the need is there. Try upgrading a coil in a cylinder.
f) Mains pressure hot water and no complex and expensive pressure safety valves.
g) The radiators are instantly heated in the morning.
h) As SimonH2 says, an immersion can give full heating and hot water backup.
I am sure many can add to them. I even know them above, just by asking the makers and reading up and figuring out how they work.
I have moved away from a thermal store for reasons that boiler technology (well only in one maker, Geminox) has caught up in supplying UFH directly and cheaply. I am having 100% UFH. If I was mixing rads with UFH I may have gone for the thermal store. My DHW needs are not great, but if it was greater I may have gone for the thermal store. My view is Geminox heating UFH only. An Intergas combi doing DHW only. If I had rads (which I may) then the Intergas may do the rads, but it will cycle heating rads and maybe needs a by-pass which I do not want, which casts questions over this way. It depends on costs.
A well designed thermal store is a great way to heat your house and give mains pressure hot water. Why a maker does not package one with ports on the side of a case, that connect easily to the boiler, the rad circuit using an auto modulating pump and UFH ports (maybe an extra for that function) is beyond me. A sludge free thermal store (to pacify the ignorant) that is easily cheaper to run would be a great selling point.
