"Roger Mills" wrote in message
...
| In an earlier contribution to this discussion,
| Angela wrote:
|
|
| That was a very useful post thank you Matthew. I "think" I now
| understand what is happening. This is a new house with a new boiler
| but I notice that the CM67 isn't sold any more - the
| developers/installers must have had a job lot to get rid of. It
| seems fine though. I have only just started putting the central
| heating on proper and it would appear that this thermostat can
| "learn" and I probably haven't given it time to do that. I'll leave
| it at the defaults for now and see how things go I think.
|
| Angela
|
| Yes, you won't get a better explanation than that provided by Andy Hall.
|
| As a matter of interest, does your CM67 have Optimum Start and, if so, is
it
| turned on?
|
| [In case you're not familiar with it, Optimum Start is a feature whereby
you
| specify the time by which the house should be warm rather than the time at
| which the heating should be switched on. The CM67 then decides when to
| switch on, so it does it later in mild weather and earlier in cold
weather -
| helping to conserve fuel. It does this by 'learning' the rate of
temperature
| rise when the heating is on, so - depending on the starting temperature -
it
| knows how long it will take to get up to the required temperature. I have
it
| on mine, and I *think* it's a good thing - but it does sometimes seem to
| turn the heating on *very* early in cold weather.]
| --
| Cheers,
| Roger

Yes it does have optimum start which will explian why it was on when I got
up this morning but according to the timer it wasn't due for another 5
minutes. I'll keep an eye on timing to see if it is turning on too early!