"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Andy Hall wrote:


That's easily addressed by having a thermostat with learning
capability which will start the heating a little earlier if it's very
cold.

Andy, do you happen to know what the earliest start time is for a CM67? I
had a feeling that it would start up to 2 hours before the target time -
but
when answering a call of nature early this morning, I found that the
radiators were hot two and a half hours before the target time - so it
must
have started even earlier. Is this normal?

A sudden cold spot can throw them out, but they learn the house and adjust
to suit quickly. .