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.

 

[Robinson]

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

Yes i seem to think this was the case. The model no 30CDI conventional

It was wired as too the honeywell Y PLAN diagrams but pump being connected to the terminals IZ NZ ( i think diditrain is correct) to boiler directly.....

 

[diditrain]

Just looked at the manual, the connections for the external pump is LZ and NZ.
This boiler had the reverse polarity issue for the pump connections. I always check with my tester now before i connect the pump.

To begin with, what i usually do is disconnect the call from the room and cylinder stat from the wiring centre then make sure that they are making and breaking when you turn the stats up and down.

 

[Dunc]

Just to clarify, is it just the pump that won't switch off or is the boiler itself still firing even when the stats are turned down? If the boiler is still running then forget belling out all the cabling initially. All you need to do first is disconnected the switch live to the boiler. If the boiler still fires with the switch live disconnected then the problem is internal with the boiler. If the boiler shuts down then test to see what voltage you have on the orange wire from the MV. If the voltage on the orange wire is still 230V when all the stats are turned down then the problem is either a faulty MV or a connection problem on the cylinder stat. However, if the voltage is between 50-150V (which is normal on a Y-plan valve) then the issue is with the boiler being too sensitive. To fix the problem you'll need a Y-Plan Capacitor Kit which will absorb the voltage.

Capacitor Kit Link

The other option is to fit a S-Plan instead seeing as how Y-Plans are such rubbish!

 

[nikmet]

It is possible to plug the pump connector on the wrong way round, it will plug onto the pins both ways!! check its correct for live to live neutral to neutral

 

[Robinson]

It is possible to plug the pump connector on the wrong way round, it will plug onto the pins both ways!! check its correct for live to live neutral to neutral

REALLY thats interesting didnt consider this. !

 

[Robinson]

Pump seems ok its the boiler is firing with cyll stat and room stat turned down. I had a feeling the boiler was firing still with switch live removed....Which worries me as you say could be internal....(could this be to do with the reverse polarity diditrain mention.?)

Diditrain was this a boiler fault or just something you managed to cause?

I get back there friday..

I staY optomistic and believe its simple wiring issue...

 

[Robinson]

SO if its wired ok as to Y plan am i right in saying all that should be different as what NOT shown on Y plan is that the LZ (over pump) from boiler now just connects directly to PUMP LIVE as too the NZ to the Neut of pump. Neither are no longer connceted to Terminal 8......But then what about switch...Where come from and go?

sorry guys ....for the hassle...

thanks

 

[diditrain]

Hi Robinson, this was a manufacturer fault not one that i created.
A batch of boilers was released into the market with this issue not sure how many in total as i cannot find the info anymore.

Can you just clarify wether it is an existing fault that you have been called in to rectify or is it a new installation

 

[Robinson]

Hi Robinson, this was a manufacturer fault not one that i created.
A batch of boilers was released into the market with this issue not sure how many in total as i cannot find the info anymore.

Can you just clarify wether it is an existing fault that you have been called in to rectify or is it a new installation

New Installation. !

 

[diditrain]

Ok
The boiler requires a permanent live, neutral, cpc, switched live and a pump over-run.
inside the honeywell wiring centre you generally have a link between terminals 12 and 13 and another between 13 and 14
This is before you put any of your cables into the wiring centre. Did you remove these links and then just put one between 14 and 12?
If you have not then with your pump still running once the boiler has fired initially it will cause the boiler to carry on firing.
Hope i am making sense as i tend to waffle a bit

 

[UNG]

From the sound of this there could be a frost stat set too high or linked out if the system is running all the time

 

[Robinson]

Ok
The boiler requires a permanent live, neutral, cpc, switched live and a pump over-run.
inside the honeywell wiring centre you generally have a link between terminals 12 and 13 and another between 13 and 14
This is before you put any of your cables into the wiring centre. Did you remove these links and then just put one between 14 and 12?
If you have not then with your pump still running once the boiler has fired initially it will cause the boiler to carry on firing.
Hope i am making sense as i tend to waffle a bit

Not actually using one of the wiring centres i think.....just termination block in box 1-10...so boiler. honeywell programmer. honeywell termination box. honeywell room stat.

 

[Robinson]

what i meant is that i believe the wiring centre is not as you described.......your not waffling at all BTW....

 

[Robinson]

From the sound of this there could be a frost stat set too high or linked out if the system is running all the time

Gonna look into this tomo ..

 

[Robinson]

OK Guys got this diagram of mate for those who need. thought well useful for dim whit like me

 

[diditrain]

Hi Robinson, looked at your diagrams and they look right apart from the y plan one where there is a permanent live going to the mid position valve. Not usually required on the ones i have connected, but i have seen a one which required it.
Is it all new components that have been fitted in this installation?

 

[Robinson]

OK WELL we cracked it ! and it was a collection of faults some poss avoided .....1st ....this morn i buzz all cables out to see if the Rev Polarity i had was me ...turns out that wasnt MY connections it was some bright spark (HOW i dont know) had labeled the 3core stat cable to Con unit and 3core Programmer cable to con unit wrong way...the stat was the prog and the prog was the stat (if you get me) Then that sorted we get on only to find out that now not switching....called WOrcester
tech he said i must have LZ NZ connected and LZ straight to pump....... on ST10 i must also have LR LS link removed + Perm live and Neutral earth.....So sorted that still not having it......fiddled and fiddled again. realised we had the neutral from pump going to the neutral at con unit. NO GOOD it had to go straight back to NZ on pump overrun...then we finding out there a reverse polarity AGAIN this time at pump....But connected ok.....SO then remembered what NIKMET said in this post about 2 pin plug and what didi said about rev pol fault.....turns out YES the pin had been set wrong way around from manufature....i know for sure it werent us.....so sorted that all good.

Now back to the boiler just firing on and off constant when prog/cyll and room stat off....Call tech again he said double check you got no voltage at LR turns out i did have which was coming in from Conn unit.....And LS was causing it......Turns out i didnt need LS at all like 1st tech told me just LR going to valve orange and cyll stat HW on......took LS out from boiler and con unit and bam fine.......why on earth do they call the LR switch when it makes a lot more sense to call LS switch....

hope this made some sense.....BUT thanks guys for all your thoughts they all help alittle throughout the day to get this job done.....

 

[diditrain]

LS is live supply to your wiring centre for your external controls-timeclock/roomstat etc
LR is live return to your boiler
Manufacturers like you to take your feed to the boiler first

 

[Robinson]

LS is live supply to your wiring centre for your external controls-timeclock/roomstat etc
LR is live return to your boiler
Manufacturers like you to take your feed to the boiler first

arrrh Yeah i see......took me a around the houses way to learn....but i got there.....Its funnny cos i have not done for so long and i know its a bit edgying doing this
with not so much experience or lost experience...but i guess only way to learn....thanks for help.

 

[gas man]

lucky to get away with reversed polarity not killing the pcb,if it was a baxi new board time

 

[Robinson]

lucky to get away with reversed polarity not killing the pcb,if it was a baxi new board time

REALLY , gosh i did worry this would of happened..What actually happens to pcb if fried , i mean does it just not fire or could it just be certain functions not work...cos i mean it all seems to function a ok. but maybe there some elements to system i not aware of that been damaged...would hate to leave customer with a issue that should of been attended to now.....i not a bodge it a scarp per type guy... I break i pay .....

 

[Robinson]

Out of interest Are biasi same story....they nothing to do with baxi are they?

 

[gas man]

REALLY , gosh i did worry this would of happened..What actually happens to pcb if fried , i mean does it just not fire or could it just be certain functions not work...cos i mean it all seems to function a ok. but maybe there some elements to system i not aware of that been damaged...would hate to leave customer with a issue that should of been attended to now.....i not a bodge it a scarp per type guy... I break i pay .....

normally reversed polarity effects the detection /ionization circuits so it generally wont detect ignition and go to flame failure sounds like no damage has occurred to your pcb

 

[gas man]

Out of interest Are biasi same story....they nothing to do with baxi are they?

yes most boilers suffer the same way,and no biasi are not related to baxi most boilers will have a Honeywell, Siemens,thermowatt pcb honeywells prone to damage with reversed polarity Siemens not so honeywells can sometimes get a soaking,dry out and work,where as Siemens die instantly with the last brand thermowatt just looking at that one will cause it to burst into flames LOL most aristons have this make

 

[Robinson]

phew. !

 

[Robinson]

Yeah i had a job before which the building contractor tryed to stuff me, in fact has stuffed me for a whole load of dosh because he said i fried pcb...WHich is utter tosh. all i done was put a programmer and stat on...it was a combi biazi......But i know for a fact they has serious water leaks just by the boiler into the boiler...anyway the boiler worked fine straight of i done my job , but the Summer mode will not work and he said its because i fried it...the case is still on...i want full dianostic from biasi and fact it was a brand new boiler and he got a dodgey NON biasi engineer out to sort it(or not) is not my prop, tyring charge me for the call out fee of this bloke too....where it all should be under warrenty...

any thoughts

 

[gas man]

tell the building contractor to rotate he is not a gas engineer,water leaks are the likely cause of the pcb damage,tell him to prove you have damaged it(he cant they are very difficult to test)see if hes prepared for you to get a gas engineer mate take a look if he wont allow you to do this he is not letting you get all the facts so its your word against his,any way whats his problem if its in warranty?just get biasi out