Hi,

Thanks for all your pointers and advice. Lots to think about.

My primary concern at the moment is to free up space in my bathroom
while refurbishing it. The bathroom is tiny and the current tank takes
up 15-20% of the space which could be better used for other things.
That's the reason for looking at a new one going into the loft.

As you say, the present tank has just one combined header tank which is
very limiting especially when it comes to adding anticorrosion
chemicals. I would love to do away with a tank altogether but it
undoubtedly means abandoning the Homeglow BBU and getting a new boiler
which I really don't want to do just yet, not until the summer at
least. This is why I'm trying to find a kind of half way house solution
but it seems that it may not be possible from what you say.

I take your point about supporting structures in the loft and I have
that planned. I haven't heard of the heat bank system which you
mentioned and would be very interested to look at this system but again
I have no idea if it that can be run from my present boiler. I'm not
sure if the Glowworm would work with an un-vented system either and
will need to establish this. I haven't been able to find much in the
way of information in the net about the boiler yet but I'll keep
looking.

Installing whatever system is not a problem as I can do the work but my
technical knowledge is lacking in systems suitability and make-up hence
my appeal for help. I would be more than happy for someone to do a good
design for me and happy to pay as well if that's the sensible route to
go.

Many thanks for your help
Kind regards and best wishes
Phillip