You have the right attitude re boiler choice. Go for quality. It is worth noting Halstead use the Vaillant heat exchanger, other makes do too. All I fit if I supply it is Buderus, they are a dream, and cost less than the vaillant. Worcester is a well known good make. All good choices. Basically stay away from the chep types places like b&q sell. Buy cheap buy twice and spend a fortune along the way.
In your neck of the woods it may cost more than 400 for the combi swap plus he may add a premium on the price of the boiler. All the other jobs required to bring the installation up to current standards would add on top.
I consider myself lucky if I get 300 for a combi swap, but I don't live in Oxford.
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Forgot to say, hoping nobody finds this contentions, but getting rid of SD sounds like a very sensible move. Put in a make which the future fitters can change parts on cheaply in ten years time, i.e. how easy is it to work on.
Of course you can put it in the middle of the lounge for us with an inspection pit underneath if you really want to make our day. If you make our life easy, you pay less for our work, it all goes according to how much work we have to do, it's not that we are difficult to please, it's you that pays for our time. If the boiler is in a kitchen cupboard which we have to twist into and use a tap spanner to undo any of the nuts, it'll take us longer, or worse we may not manage to change the necessary part. In not a few sd's have I failed.
