Boiler Stove / Thermal store system design

22 Nov 2019
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United Kingdom
Hi,I’m planning on installing a boiler stove and thermal store and would be chuffed if someone in the know could take a look at my design and tell me if it’s feasible/safe/legal. It’s a bit of an awkward system because the thermal store has to be on the same level as the stove and the pipe work has to go up and down to reach the store. I put a heat loss radiator above the stove with a check valve on the outlet, the idea being that the stove will thermosyphon through the radiator via the check valve when the pump is not running and when the pump is running the check valve will stop backflow through the radiator. See what you think

many thanks



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I think you've identified the problem yourself - the thermal store is on the same level as the stove, and it's not heated by gravity circulation. The thermal store tappings need to be at least a metre above the stove tappings (centre to centre) and the pipework should rise continuously from stove to store.
Thanks for the reply muggles. Unfortunately I can’t position the stove or the boiler anywhere else so have to try a workaround. The pump should circulate the water through the store and stove normally but if there is an issue with the pump or there’s a power cut then gravity circulation through the heat loss radiator would take over to prevent overheating of the stove if it happens to be lit at the time. I’m no expert but I can’t see why this wouldn’t work, not sure if it complies with the regs tho.
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I could route the return pipe under the downstairs floorboards, it would mean a bit more work lifting more floorboards tho. Do you think this would help?
What is the purpose of the 3 port valves?
Seems like it is adding unnecessary complication.
The return stat on the stove should be wired as a standard hi-lo configuration with the Hi stat.
Which allows the return stat to energise the pump.
The Hi stat is just a back up.
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The valve on the stove circ pump is to control the temperature of the water being supplied to the stove as I read somewhere this will improve efficiency. The valve on the right of the diagram is to control the temperature of the water in the radiator circuit. You are right in that it’ll work without them and I may leave them out when it comes to installing the system
Are you using the thermal store to provide hot water to the taps?
Yes radiators and hot water, didn’t show it in the drawing tho. I’m planning to get a cylinder with a coil in it for the hot water
Far better to pump Ch straight to the rads. Which will be the excess.
The hot water already hot.
Which is how these systems are traditionally plumbed.
Ok, I’ll put the ch pipes further down the cylinder. Do you mean pump the water straight to the rads without a three way valve?


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