Just to say you don’t have to involve HETAS. I was quoted 2K just to line the chimney and fit the thing from two HETAS guys near me. It actually cost me £1500 including knocking out the chimney breast, plastering inside, new hearth, liner, stove etc.
I did this by doing my homework on the regs, then getting it fitted by a competent builder and signed off by the local authority. None of it is rocket science if you take the time to read Part J of the Building Regs and work out what you need – its all pretty straightforward stuff.
Its a good and valid point martinhutch, I have not looked into the regs that much TBH, I am only going on what my home insurance company seem to want if I have one fitted.
But I think I might look it this a bit further, thanks for the tip.