Worcester boiler/Honeywell remote question.

[Richard Blackwood]

I have a Worcester combi boiler controlled by a Honeywell CM61NG RF programmable thermostat.

It is set on AUTO to come on between 7-8 am, 4-5pm and 7-8 pm. The last 2 nights it has come on at around 4.30-5.00am. When checking the remote's LCD at 4-5 in the morning, in addition to seeing the usual AUTO it also has OPT on it. There is no mention of 'OPT' in the booklet I have for it. Anyone know what it stands for? Optimal? Optimum? And anyone know why the damn thing might be coming on unasked for?

[Andy Hall]

It's an optimising controller, so this is normal behaviour. It has calculated that in order to reach your required temperature by 0700, it needs to turn on the heating two hours earlier with current weather conditions.

more details.

It makes sense to use this normally, although if you don't need the house up to temperature at 0700 and have set that to allow the system time to warm the house, you don't need to do that and could set the time later.

THe installation instructions have a bit of information as well, but mainly how to turn the optimisation on and off. It's usually better left on.

[Hippo]

From the website "What is optimum start

Instead of switching on the heating at the set time every day, theCM61NG will delay the start time to the latest possible moment, so that unnecessary heating is avoided. All you have to do is set the time when you want comfort temperature and the CM61NG will then decide when to turn the heating on, thereby ensuring your comfort"

~~~

Hippo