Pre heating water into combi boiler?

[ianmcd]

Update:
I contacted Worcester Bosch who advised that my particular model of combi wasn’t suitable for pre heated water.
I’ve decided to go with a direct unvented cylinder plumbed in such a way that in summer when I have spare power I can bypass the combi and draw hot water from the cylinder and revert to the current combi fed system in winter. Simplest option in terms of plumbing and should be pretty fail safe - if either the combi or the immersion fail I can switch to the other.

Not 100% sure but I think the reason your boiler cant handle it , is your boiler has a cold water inlet temp sensor, and I think pre heated water would confuse the boiler algorythms, there are boilers that can be used like this, but I am a gas engineer not an oil engineer so dont know of any oilers that can