Thermal store query

[Nosredneh]

Can anyone tell me if this is a recognized way to plumb in a thermal store. I have a combi TS with MPHW. The circulation pump is on the return to the boiler close to the TS which I believe is correct, however this is the bit I cant get my head round. After the pump is a mid position valve which diverts the TS straight to the boiler when hot water only is called for and then feeds back from the boiler to the top of the TS. OK so far. Now the strange bit. When central heating is called for the valve moves over and diverts this return flow to the radiators and I should imagine it then returns to the boiler on the return to the boiler on the other side of the valve. When the valve is in the mid position it flows through both ports. Why? Surely a two position valve is all that is required to keep the store fed under all circumstances, and should the CH be fed from the return to the boiler.

Thanks in advance

 

[ianmcd]

what is a combi TS ? your post is very confusing, please post some pics of what you actually have

 

[hard-work]

You need to be more specific.

 

[Nosredneh]

TS=Thermal store (cylinder)
Combi TS =Combined Thermal Store in this instance an open vented cylinder with feed and expansion tank mounted on top. Water in the cylinder is heated directly from the gas boiler and stored in the cylinder at 85 degrees C.
MPWS= Mains pressure water supply.
MPHW= Mains pressure hot water
Hot water is stored in the cylinder and is used to heat the MPWS to the hot water taps, shower etc.via the internal heat exchanger and mixer valve. The stored hot water is also the central heating water so we get instant central heating warm up.
My question is, is it normal to feed the central heating circuit from the boiler return. Surely this is the coolest part of the system. Where would the return from the central heating be plumbed in? Into the boiler return on the other side of the mid position valve or into the feed pipe from the boiler back to the cylinder.

Hope that's a bit cleared folks.

 

[oilhead]

If the boiler flow is only going through the thermal store, then it is hardly going to be cool. is there a thermostat that gives priority to the thermal store before the heating valve opens?
Do you have a problem with heating? If not, then don't fix it.