Don't know boiler model at the moment if this info is needed, it also
looks a few years old so may update with a new one if needed.

If you've got a lot of fluing involved, seriously consider the Keston
Celcius. Although it costs more than many boilers, this is easily offset by
the fact that it uses 50mm drainpipe for the flue, costing pennies, rather
than hundreds upon hundreds for large proprietary flue extensions that might
have difficult fitting up a chimney.

BTW, I'm thinking of doing just this for my cooker, except without the
boiler complications. I was going to use multiboard rather than aqua panel.
It is the modern equivalent to asbestos sheet. I had to widen my chimney out
though. It was 89cm wide and the cooker was 90cm. :-(

Christian.

Currently doing a similar thing. The old boiler was vented up a stainless
liner in the chimney. I'm just going to install an under-cupboard type
cooker hood above the cooker in the chimney opening and vent this up the
liner. The hood has washable stainless fat-filters so no too much fat should
go up and coat the liner.