In article ,
"Edward Holt" writes:

Thanks for the good advice.

I'm in Scotland and this combi is a replacement for a non-condensing Ariston
unit which failed after 10 years.

In that case, Part L may not apply (I don't know the Scotish equivalent).

The radiator without the TRV does stay warm - very warm, easily the hottest
one in the house (it's in the hall).

I was concerned that if I had the heating on the boiler set to max then the
TRV would reject the hot water and the radiator without the TRV would get
all hot water and get dangerously hot. I guess that having a room stat would
avoid this?

It would avoid wasting energy when the hall doesn't need any more
heat. Ideally, you would have it in the room which is slowest to
heat up, so it doesn't switch off until the others are up to temp,
but it must go in the room with no TRV, the hall in your case.

--
Andrew Gabriel