"Ed Sirett" wrote in message
news
On Thu, 17 Nov 2005 19:39:20 +0000, Doctor Drivel wrote:


"Ed Sirett" wrote in message
news
On Thu, 17 Nov 2005 08:48:54 +0000, graham wrote:

On Wed, 16 Nov 2005 23:25:45 GMT, wrote:


What do you mean by 'optimiser', and what have you looked at?
What I recall was gizmos sold many many years ago to prevent (or
reduce)
boiler cycling, but this shouldn't occur with a properly designed
system
to
current standards.

It has an internal and an external heat sensor.

You set the optimiser to reach a particular temp within the property.

You then set the timer. The system will then calculate (based on the
temperature sensors) when the boiler needs to switch on and off.

The whole idea is that if you set the optimiser from, say, 6.00am to
8.00am that the house will be up to the correct temperature (allowing
for local fluctuations within the house) at 6.00am.

On a warm morning the boiler might switch on at 5.30am to achieve
this. On a very cold morning the boiler might have to switch on at
5.00am to achieve this.

Similarly, if it is warm outside but initially cold in the house the
boiler might be able to switch off the cycle completely at 7.30am.
However, if it is still very cold outside it might wait until 8.00am.

We have an optimiser system fitted at work.

It means that you save gas and you know that the property will always
be at the correct temp during the precise periods that you want the
heating.

If you want this level of sophistication cost and complexity are part
of
the territory. Opinions vary on this matter including the opinion of
people I respect greatly.
Costs of the Honeywell CM67 seem to be around £75

More like £50

and people who have
them seem happy that they are programmable with a reasonable ease
relative
to the complexity.

IMHO a simple programmable thermostat is about £30. Since the
night time temperature will be maintained (at say 15C) the system only
has
to heat the house by a certain maximum amount in the morning.

You opinion is lacking then. For £20 more you get far more, far more.
Well
worth it all around.

(I don't believe that) You are in the position that you have to
_explain_ the operation of the heating controls to purchasers.

Even the simplest programmable stat is much too complex for some people.

This is easier as all you do is punch in the occupation times, leaving out
any warm up times.