control problem, stuck

[ambrosia]

about 3 months ago I installed a new vaillant 430, I also changed the pump and cylinder stat at the same time
All was well until just before christmas, customer called me and said heating and hot water were stuck on, went back checked and changed the actuator on the 3 port zone valve (actual valve was moving freely so didnt change the body) and at the time i broke the drayton wireless room stat so put a new one in

now the only thing which hasnt been changed in the programmer, but this was changed a year ago and seems to be working fine

In trying to diagnose the fault before christmas I ended up re wiring the control box so fairly confident that isnt the problem

however after I left everything was fine for a few days, then went back to the same problem of the boiler being constantly on

when i installed the boiler I used the original wiring and it doesnt have pump over run, the link is still in the switch live and when not calling for heat power to the boiler is completely shut off

I wondering if its reverse polarity somewhere, but what is really confusing me is its an intermittent fault, pretty much everything has been changed and its still happening


any helpful suggestions will be gratefully received because i really need this problem to go away

 

[Chalked]

Did you wire the Om stat back to the boiler? If so did you remove the link?

 

[Rabbitman]

Do you have the vaillant wireless controls

 

[ambrosia]

whats an om stat and no vaillant controls

link is still in but the boiler is supposed to be completely dead 'as in not even on stand by' when theres no call for heat

 

[Tonycane]

What programmer is it? Recently had this with a Honeywell st9400, swapped it and now is all good

 

[ambrosia]

its a drayton programmer, but surely if the cylinder stat or room stat reaches temp it'll over ride the programmer. that said ive tried everything else

 

[gas2016]

Might sound like a silly question but did you remove the bridge from the 24v plug with RT written on it?

 

[ambrosia]

no thats the whole point, the boiler only has 3 core, live neutral and earth no switch live. the live is the switch live

went back today, looks like its the wireless stat, its somehow intermittently sending a live to the white in the 3 port valve

 

[gas2016]

It's not a salus is it!!!