valve question

[bjorn dunderbeck]

Me again guys I have been running the system manually for a while now but my dear wife drew to my attention that she isnt happy with it so here we go again...I wont go thru the whole thing again but the bones of it are quite simple......suprima 50 ...boiler works ok as far as I can tell ...
my question is ,how does the motor move from its resting position )hw) to the first microswitch??
to get the thing working I have persuaded the motor to turn and it is not until the first microswitch is depressed that it moves under its own steam,the second is then pressed and it maintains that position until call 4 heat is satisfied , it remains in that position until hw is called for and the spring pulls the valve to that position and there it stays!

so why is there no power before the first switch is depressed??is something broke or is the spring pulling it back too far?
please help

___________________________________
Moderator

split from hi-jacked post

 

[ChrisR]

Check the wiring on the Honeywell site - sundial plans.

If that's OK change the head.

 

[MANDATE]

The rest position relates to HW only. (Power goes through cylinder stat direct to boiler /pump etc). When CH is selected power also goes through the room stat and to the 'white' wire of the valve and it is this that drives the motor forward upto the mid position and activates the micro switches.
At the mid position one of the switches cuts off the intial route and creates a second route, but the second route is via the diode/resistor which is enough to hold the motor against the strengh of the spring.
When HW is satisfied the cylinder stat cuts off the original supply direct to boiler/pump and introduces the supply to the 'grey' wire of the valve which now takes over from the reduced power level and drives the motor forward to the CH positon and keeps it there against the spring tension.
Power to the boiler comes from the orange wire when CH only
Power to the boiler comes from the cylinder stat when HW only
When on HW and CH power is fed along both routes, hence the reason why you can have heating with a faulty valve (microswitch faulty) as long as there is a demand for HW.

 

[bjorn dunderbeck]

happy now.got in from work and decided to tackle this once and for all .pulled the pcb from the potterton had a real close look and what do I find?cracks around the joins of the longest connector fan/gas/cutoff .i think,...re soldered them,
now all is well in my world thanks to all for your help also i think the tabs attatched to the synchro motor/valve cog had been bent away from the microswitches so they were not hitting them at the right time hope there in the right place now....
ta again