Boiler tripping main consumer unit help

[plugy]

I have a halstead best conventional boiler, that went to lock out and would run its cycle so we replaced the aqua-stat and away it went with a noisy fan.
Couple of months later boiler wouldn't cycle again the fan bearing finally gave up so the fan was changed.

Now you turn on the boiler, everything comes on as should goes through its cycle and the boiler fires up, then between 10-60 it trips the main electric.

The boiler this time does not go to lock out as before with the othere two problems but trips whole electric anywhere from running 10 -60 seconds, totally stumped any ideas!!!

 

[Agile]

Does it trip the RCD or an MCB?

Usually RCD caused by a faulty pump. Would need to monitor the current to earth!

Tony

 

[plugy]

The mcb stays on it trips the main rcd on the board, i have not looked at the pump yet, but if a bad pump would this not trip straight away and not intermitanly?

 

[andytw]

....but if a bad pump would this not trip straight away and not intermitanly?

You could ask this question of anything.
Intermittency is often related to heat, pumps get hot.

andytw

 

[plugy]

funny how when the fan and stat went (on separate occasions) the boiler would just sit on lock out doing nothing not tripping electric.
So i lean more towards something else as you say maybe pump.
Halstead technical help say due to it tripping electric it is a large component not a low voltage part (thermister ect) like fan, stat?
I will disconnect pump and try again.

Not much elese really to replace on these boilers very little components.

 

[andytw]

funny how when the fan and stat went (on separate occasions) the boiler would just sit on lock out doing nothing not tripping electric.
So i lean more towards something else as you say maybe pump.
Halstead technical help say due to it tripping electric it is a large component not a low voltage part (thermister ect) like fan, stat?
I will disconnect pump and try again.

Not much elese really to replace on these boilers very little components.

You can't make comparisons and set your own expectations. e.g. funny how when the stat and fan failed etc.
It isn't 'just a boiler', it is lots of seperate parts, all prone to failure in their own unique way. e.g. the fan had a failed bearing.
The previous problems are almost certainly not related to this problem.
The pump is being suggested, from experience of the people on this forum, and as it it is mains operated, has a tightly wound and insulated coil of wire inside an earthed body any failure of the insulation will cause current to flow to earth and trip your earth leakage trip.

andytw

 

[oilhead]

The pump is not part of the combustion cycle as are the other components. This is why the boiler does not lock out.

 

[plugy]

Had new fan, aqua stat and thermistor, i disconnected the pump to take it out of the equation boiler run for so long then tripped again so cant be pump either.

Though maybe over sensitive trip so change to other side of board to different rcd that still tripped.

One noticeable thing once boiler runs for length of time and trips it will continue to trip once re set till left for couple of minutes.

So maybe boiler thermostat doesn't have a room stat? Halstead technical seams to think not as this is a low voltage part and wouldn't trip main electric.

Only really gas valve left.

Totally stumped?

 

[Agile]

I would be identifying the problem by measuring the earth leakage current with my clamp on meter.

Tony

 

[plugy]

Have now got british gas looking at it 3rd person royal rip off but cannot afford to replace boiler (although may have to)has got everyone totally baffled.

There is nothing left only gas valve, pocheometer and thermostat everything else replaced.

Any ideas of top of your head?