"Doctor Drivel" wrote in message
...
It is no good putting a modern boiler on an outdated DHW/CH system. Go
for gold.

I'm interested in what you define as an outdated DHW/CH system. For instance
I have a Y plan system with a Honeywell optimising thermostat. If I
installed a new boiler what changes, other than a more efficient bolier, is
going to make a difference?