Baxi Combi Instant 80 HE tripping RCB

[spamnchips]

I have just bought a house in which a Baxi boiler was installed in 2008. The system worked perfectly OK. As there was considerable repair work needed to the property, we shut off the system, drained the central heating down and got on with the building work. Now everything is complete we have re-mounted the radiators, refilled the system. Now if we switch on the boiler it throws the main RCB. It appears there is a short somewhere. I have isolated the main switch and removed the connections everything is fine as they are re connected until the feed to the PCB is connected and the rcb blows again. Any ideas please as I am scratching my head in vain.

 

[jackpike]

check polarity,

 

[spamnchips]

But nothing has been changed since it was being used to provide hot water and central heating.

 

[jackpike]

you said major repairs have been done, so if somebodys done any electrical work and crossed the wires somewhere, this will cause a polarity problem,,i'm only guessing here, but its easy to check if you have a socket tester,

 

[matt1e]

I have just bought a house in which a Baxi boiler was installed in 2008. The system worked perfectly OK. As there was considerable repair work needed to the property, we shut off the system, drained the central heating down and got on with the building work. Now everything is complete we have re-mounted the radiators, refilled the system. Now if we switch on the boiler it throws the main RCB.

since you have had work done I would firstly check that the problem doesnt lie outside the boiler ie damage to external control wiring etc

do you have test equiptment?
if not disconnect the external wiring from terminals 1& 2 and replace with a link
restore power to the boiler and see if it still trips out
if yes the fault is internal to the boiler
if not then the fault lies external to the boiler (controls, damage to a cable etc)

Matt

 

[spamnchips]

Sorry I should have been more specific. Repairs were wall building and plastering. Nothing electrical. If there was any damage to the boiler electrical supply then surely it would blow the RCD regardless of whether the boiler switch was on or not. This only happens when the boiler switch is turned on, either to hot water or hot watre and central heating. As I previoulsy explained. I have removed all the connections to the master switch and the RCD does not trip indicating that the feed to the boiler is OK. I have then put them back one by one. The black wire, the red wire etc., and when the brown wire from the switch to the PCB is connected it blows the RCD. This points me to something wrong with the PCB or further on.

 

[picasso]

disconnect the fan , pump and gas valve, connect the pcb and turn on the power, it shouldent trip the rcd, turn off the power and connect one at a time until you find the one tha is shorting or use a mm to find the culprit.

 

[spamnchips]

Thanks Picasso, I'll give that a try.