Old type central heating control

[stephen craddock]

Looking at this design it appears that if both HW and CH are on simultaneously the room stat is ignored until the cyl stat is satisfied. i.e. room temperature can exceed room stat setting.
Am I correct in this observation?

 

[cross thread]

Yes its priority hot water,often so a smaller output boiler could be used

 

[stephen craddock]

Just noticed it as I was playing at getting rid of this mixed function to allow the controller to exclusively enable HW or CH. Done this by connecting the Grey wire to the White wire connection at the controller. Finally got rid of the horrible diode function that has just been consuming 2/3W all night for the winters. If everyone did this it would save the country many MW of power each year but I suppose that this old style control is becomming obsolete so who cares now!

 

[Nige F]

Bit like the pilot light on my gas boiler.

 

[stephen craddock]

At least it's more enjoyable looking at a nice blue pilot light than it is a warm diode