Well, further to the thread I started on the 23rd, system's been upgraded by
a Worcester Bosch Combi 30 Si running 11 radiators, 9 of which have been
fitted with TRV's. Rads are piping hot when the TRV's are set at maximum but
obviously they're now all being adjusted down to a comfortable level. It's
going to take a bit of time but we are happy with it. The bath doesn't take
that much longer to fill than before but we have to remember to fill with
hot water first then once it's at a level close to where we want it, we top
up with cold.
After much debate at home, and comments from this NG, we have decided to
continue with the fitting of the Mira Sport shower tomorrow. It gives us
that extra flexibilty if something happens to the gas supply at any time.
Have you considered adding some kind of mixer so that the bath fills in
one go at the correct temperature? It would be safer, particularly if you
have young children or elderly relations using the bath.
Screwfix sell thermostatic mixers which might be suitable.
Bloody useless if you're having a long soak and need to top up the bath
with hot water. If you have vulnerable users you could use a bar shower
mixer for filling since they have temperature limit stops which you have
to deliberately override to get the hottest water. There's a model I've
seen on one plumber's merchant around here which comes as a bath/shower
mixer and costs about £100: otherwise you're looking at several £00.