Reverse Polarity blow PCB? Worcester boiler with overun

[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