Reverse Polarity blow PCB? Worcester boiler with overun

[Robinson]

Ok guys had a day and half today....Y plan Honeywell room stat, 7 day prog 2 channel.
Worcester boiler with over run......

Some how the mains L/N got cross and had few 3 amp fuses blow in spur before we established issue...boiler fuse was ok though and once established that a donkey had connected wrong way around we continued with setup.....Seemed to have all wiring correct. But Cyl/Stat and Room will not turn Heating or water Off ......pump runs but no switching off...tryed turning cyl stat right down and room stat but boiler still fires...

I have heard that because the over run is controlled by pcb it could be this causing prob....ie. pcb been damged by reverse polarity thus now keeping overrun on....

I dont have all details on boiler model or actuator etc at mo...But wondered if you knew of any other maybe cause's or if any of you got links to diagrams of Y plan with pump over run......got one on honey prog and seemed all good but maybe we have got something wrong regarding the over run cables.....as that was not on the diagram, only on boiler elec diagrams which were alittle confusing...

 

[Big n Daft]

Go back to basics, clear the mind.
1, Check the wiring is correct with no faults. Point to point ,buzz it out.
2, Check components of the heating system for electrical integrity. Valves, pumps, stats and stuff are switching and free of earth faults etc with an multimeter.
3, If you feel confident then force feed the components from the controller/boiler and confirm operation.
4, If everything works then the pcb is duff. But you must satisfry yourself it all works first.

Only done one heating system and had similar trouble me'self due to a dodgy plumber.

 

[nickblake]

Agree with big and daft ..............top answer......................see your not as daft as you made out in other thread lol

 

[Robinson]

clear the mind..

Yes this is defiantly the hard bit. Yeah tomo gonna start buzzing out it has new prog, new valve, new stat, so shouldnt be them....was concerned and the L/N error tho...last thing we need is new PCB....

 

[diditrain]

There was a reverse polarity issue on worcester boilers not so long ago if i remember correctly. Recieved an email from the manufacturer

 

[truckster]

Not got the boiler details but just as an obvious thought have you got the live/sw live(if there is one) in the right way?

Another thought, don't know if it's applicable but some boiles will fire on around 150V, there can be enough leakage onto the orange sw at the valve to give this. If thats the case you have to install a 230V relay into the boiler sw wire. Don't get a manufacturers one they wll cost about £65, go to the w/salers and get one for a fiver.

 

[PC Electrics]

Have you removed the link between Lr and Ls?

 

[Robinson]

Have you removed the link between Lr and Ls?

Yeah link was removed......but wasnt too sure on the terminals for over run. another little terminal block on two pins with LS NS only, its says you need this
direct to pump which is cool, but was confused as to whether we need neutral there too as well as over on ST10 terminal block where the link was... thought this might of affected it too

 

[diditrain]

what model is the boiler. Not 100% certain but i seem to remember one i done and i think the connections for the pump were iz and nz

 

[sparky3366]

the pump over run is just a case of wiring the pump to the boiler (pl &pn) or lp np..., switched live and then normal l,n,e.