Myson Orion boiler trips RCD randomly

[whoasamisami]

Hello,
I have a Myson Orion fanfare 30si that randomly trips the entire house out. I am certain that it is the boiler (it will on occasion be instant as boiler attempts to fire up + i have disconnected various other circuits leaving only boiler on) that is causing the issue and have taken various steps to solve it. I have replaced Thermostat, PCB board, Timer/programmer, room thermostat and tidied up earth connections inside boiler...... none of which have solved the problem...

In addition to these attempts, i can tell you that on occasion the fault will not occur for longs periods of time, a week being the longest. THe issue has been occuring since start of year and i have had no other DIY done in vicinity of boiler electrics in this time....

Has anybody got any other ideas!!???? PLEASE?

 

[Agile]

Amazing how you blindly change expensive components!

Statistically its most often the pump, followed by leaking motor valves.

Real boiler component failures are extremely rare.

To diagnose those faults I measure the leakage current from each part of the house.

Often RCD trips are caused by a high leakage current from somewhere else which together with a boiler ignition current adds up to enough to trip.

Tony

 

[whoasamisami]

Amazing how you blindly change expensive components!

Statistically its most often the pump, followed by leaking motor valves.

Real boiler component failures are extremely rare.

To diagnose those faults I measure the leakage current from each part of the house.

Often RCD trips are caused by a high leakage current from somewhere else which together with a boiler ignition current adds up to enough to trip.

Tony

Daft i am i know, although i have not spent as much i could have! Have had access to various spares and already had room stat whilst prgrammer can be returned.

Still your opinion is apreciated, gives me some knowledge..

Cheers

 

[Agile]

It was the PCB I was more concerned about as thats usually quite expensive and cannot be returned.

There are many who think that a boiler should be fitted to a non RCD supplied dedicated spur.

Practical considerations and interpretion of electrical regulations usually make that difficult now.

Tony

 

[whoasamisami]

Amazing how you blindly change expensive components!

Statistically its most often the pump, followed by leaking motor valves.

Real boiler component failures are extremely rare.

To diagnose those faults I measure the leakage current from each part of the house.

Often RCD trips are caused by a high leakage current from somewhere else which together with a boiler ignition current adds up to enough to trip.

Tony

I can safely say it is not the pump as it will run without issue when thermostat turned off, whether this is normal i am unsure. As to whether other "leakage" is contributing.... the trip would happily go when nothing other than fridge is running......

I read on another forum post that the "suppression capacitor" in boiler could be likely cause??

 

[whoasamisami]

It was the PCB I was more concerned about as thats usually quite expensive and cannot be returned.

There are many who think that a boiler should be fitted to a non RCD supplied dedicated spur.

Practical considerations and interpretion of electrical regulations usually make that difficult now.

Tony

PCB was cheaper than an unknown engineers call out charge so i opted to take the gamble.... my bad!

I do agree, with my limited knowledge that if the boiler not on RCD then the trip would probably never happen.. sadly as you say this unlikely to be alowed these days...

 

[Agile]

Few boilers have supression devices. They do sometimes go short circuit but dont normally trip RCDs as a new fault.

How long have you run the pump for on its own?

This shows how difficult it is to fault find without test equipment!

Tony

 

[whoasamisami]

Few boilers have supression devices. They do sometimes go short circuit but dont normally trip RCDs as a new fault.

How long have you run the pump for on its own?

This shows how difficult it is to fault find without test equipment!

Tony

These boiler definitley has a supressor in it...

The pump ran for an hour or so, then i switched thermostat back on and boiler was fine... heating both water and radiators.. IT would appear on occasion that the issue was related to both functions being active at same time but then all would return to normal... This for a time led me to thinking that it may be zone valve, so i abandoned using boiler to heat water and reverted back to the immersion heater, all was fine for some time then trip went again...

I need to bite the bullet and get a sparky with test equipment to spend some time..... don't i!?

 

[Agile]

Can you post a photo of the supressor?

It sounds like a fault in a motor valve leaking. Have you removed the cover and looked for signs of water leaks?

Or take off the head and leave it off for a while?

Tony

 

[Agile]

Few electricians will manage very well with earth trips on heating systems.

Slightly more boiler engineers would be able to. Most would just change parts at your expense though.

I enjoy challenges like those though.

Tony

 

[vicvapour]

It was the PCB I was more concerned about as thats usually quite expensive and cannot be returned.

There are many who think that a boiler should be fitted to a non RCD supplied dedicated spur.

Practical considerations and interpretion of electrical regulations usually make that difficult now.

Tony

Not at all Tony, this is a common misinterptretation of the 17th edition regs.

Surface mount the wiring in mini-trunking .The socket-outlet would need to be specifically labelled or otherwise suitably identified for connection of the particular item of equipment.

Regulation number(s)
522.6.101
522.6.103
411.3.3

 

[vicvapour]

Amazing how you blindly change expensive components!

Statistically its most often the pump, followed by leaking motor valves.

Real boiler component failures are extremely rare.

To diagnose those faults I measure the leakage current from each part of the house.

Often RCD trips are caused by a high leakage current from somewhere else which together with a boiler ignition current adds up to enough to trip.

Tony

At no point did the OP stipulate the boiler circuit was protected by an RCD.

The OP could be refering to an MCB which if it was tripped would indicate an overload or short circuit fault and not earth leakage current.

 

[Agile]

At no point did the OP stipulate the boiler circuit was protected by an RCD.

The OP could be refering to an MCB which if it was tripped would indicate an overload or short circuit fault and not earth leakage current.

Oh dear! He states RCD in his heading!

Not many of my customers would want a surface mounted cable across their new kitchens! Particularly when there is no requirement for it.

Tony

 

[vicvapour]

At no point did the OP stipulate the boiler circuit was protected by an RCD.

The OP could be refering to an MCB which if it was tripped would indicate an overload or short circuit fault and not earth leakage current.

Oh dear! He states RCD in his heading!

Not many of my customers would want a surface mounted cable across their new kitchens! Particularly when there is no requirement for it.

Tony

Ah righ, i should have gone to spec savers, i see the heading now, i know surface mounting doesn't look too good but it is permissible to have this socket non-RCD as long as it labelled, and recorded on a MWEIC.

 

[vicvapour]

At no point did the OP stipulate the boiler circuit was protected by an RCD.

The OP could be refering to an MCB which if it was tripped would indicate an overload or short circuit fault and not earth leakage current.

Oh dear! He states RCD in his heading!

Not many of my customers would want a surface mounted cable across their new kitchens! Particularly when there is no requirement for it.

Tony

Ah right, i should have gone to spec savers, i see the heading now (i just read the post first), i know surface mounting doesn't look too good but it is permissible to have this socket non-RCD as long as it labelled, and recorded on a MWEIC.