Mixer valves for thermal store?

[Doctor Drivel]

Some combis have a low level pressure detector and will lock out. Most do do not. If it does not you can use it on a vented system. A boiler connected directly to a heat bank is far more efficient, than heating the cylinder via coil. You will find that the makers use the same heat exchangers on the vented and system boilers/combis. It will perform better on a vented heat bank as there will always be full flow through the boilers heat exchanger. The pump on combis are mainly on the return, so always cooler water on the pump side. The pressure vessel in the combi is just ignored. If it ever leaks just cap it off.

[PCPaul]

I've got the installation guide for the boiler (a Vokera Linea 24). It gives details for combi, S and Y plan installations by changing jumpers, so I'm happy that it will drive it satisfactorily.

I checked with them about feeding the solar preheated water directly into it (an posted about it ages ago) - they said the feed had to be below

28C. It doesn't seem worth replumbing the existing (wrong) solar arrangement just to gain that much preheat.

(The only way I can see any logic in the current arrangement is that the fitters expected to feed warm water into the output of a mixer and have 'Hot' and 'Cold' come out of the inputs...)