Vokera 20/80 Flowmatic not switching off via external timer

[glyned]

Can any one shed light on this problem? The boiler CH and DHW are both working as they should, pressure around 1-1.5 bar, DHW temp fine and rads heating normally (rad valves fitted) but the damm thing refuses to switch off/on via the timer and has to be switched off at the mains as the boiler switch also fails to put the boiler to sleep.

I hope someone as an idea, many thanks in anticipation

Glyned

 

[glyned]

Here's more information, with the boiler switched off (red neon) the timer will do it's job and switch off the boiler CH but this leaves us with no DHW as the boiler is off. With the Timer disconnected the boiler switch (red neon) switches off/on the boiler CH & DHW but this is with the three way switch on Timed not Contstant and with no loop between 1 & 3 on terminal block.
Have checked PCB and as far as i can tell there is no fault after testing with multimeter.
My trusted heating engineer as not yet got back to me and the other two engineers I used, one now works full time for Worcester Boilers and the other retired to sunnier climbs.
I hope someone can point me in the right direction, thanks in advance.

 

[twgas]

sounds as though your diverter may be sticking, but all your boiler switching on/off has confused me rather somewhat

 

[DP]

Here is a warning before you start messing about in the guts of the boiler. It has 240 on a lot of electrical components. So, lethal hazard exists. Do not say I did not warn beforehand.

SWITCH THE POWER OFF AT THE ISOLATOR FEEDING POWER TO BOILER.
Connect one probe of multimeter (OHMS range) to terminal 34 and other to either 33 or 35. You should not get a short circuit indication on the multimeter.

If you do, change the triple micro switch front of diverter. Post results.

If above is clear (high resistance), check spindle on diverter is not sticking out. If it is, push spindle in (using gentle pressure on micro switch lever). Check if the spindle stays retracted and only pushed out when HW tap is run.

Post findings

 

[glyned]

Thanks twgas and DP, yes DP there is a short between terminals 34 & 33 and 34 & 35 but the spindle on the diverter is working OK. I have a service kit for the valve (Summer job), but looks like I will be needing a micro switch as well. Sorry if all the switching on/off confused you twgas, just clutching at straws trying everything (a schematic may have helped). As an retired electrician I know the perils of 240v, but you can never have too many warnings, thanks again both. DP can you explain the operation of the three way micro switch and why it's causing this problem with the boiler not shutting down.

Cheers

 

[DP]

Can you contact me via email in my profile.