"Harry Bloomfield" wrote in message
. uk...
Set Square wrote on 08/02/2004 :-
This seems to be working, but I'm curious to know what algorithm it uses
in
order to decide when to turn on the heating. The literature doesn't make
this clear, so I wonder whether any of you actually know?

20 years ago I designed one of these controllers and the next stage in
its development was to include the facility which you mention. The
whole idea was well ahead of the market at that time, so I was
struggling on new ground.

Self adaptive optimum start, and optimum stop, controllers have been around
on the commercial field for over 20 years. Microprocessor based too.

I got as far as working out a rough algorithm. It went something
like...

Starting with a basic programmed in setting, then incrementing or
decrementing preheat time value, based on whether it attained the
temperature before or after the set time. Which equates roughly with
your last suggested method.

It was all very experimental. There was a theory going around, that in
order to achieve this function, that an outside temperature sensor
would be needed to enable the calculation to be done satisfactorily. I
wonder if your unit includes an outdoor temperature sensor?

It is far better with an outside temperature sensor, But using just one
inside temp sensor, a decent optimised start performance can be achieved.

The DCD controller has a number of user set time zones during the day. Each
one is optimised on and off (I believe). The CM67 is only optimised on, in
the morning period, so I believe. Subsequently the DCD controller saves a
lot on energy.