"Peter Taylor" wrote in message
...
Michael Chare wrote

With a conventional programmer the boiler is trying to keep itself warm
whenever
the timer says the C/H is on which in your case would be always.

This is not true, certainly not in every case.

As Tony Balir would say "You have to consider the totality of what I said". :-)

My post was about gravity systems without H/W tank Thermostats, and would also
apply to gravity systems with H/W Thermostats which control a zone valve on the
gravity side which does not have the additonal contacts for controlling the
boiler. (As installed by some else in my house.)

Michael Chare