Our combi trips at random times. It has preheated water for start up. If we turn of boiler after trip reset trip then turn boiler on it trips imediatly. If when it trips we leave boiler on there is a bit of resistance to switch on trip switch but boiler starts up fine after a couple of tries switch pulls. Any ideas please?
Boiler electrical fault
- Thread starter Baconite
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- 27 Jan 2008
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- Llanfair Caereinion, Nr Welshpool
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Trips what?
One of these or something else? The RCD and RCBO can present problems finding the cause, and likely will need some test equipment to find out what, it may not be the item which when used causes the trip, although normally it is.
The problem is made harder due to gas safe rules, Electricians will have all the tools of the trade, but may not be allowed access to the boiler, where a plumber may have his gas safe registration but may not have the tools required.
In the main heating and ventilation engineers span both trades, but here in mid Wales hard to find, so what we want to do is guide you to finding out if really the boiler at fault.
So with my house very little uses same circuit as boiler, and it is oil anyway so no need for gas safe guy, so when my RCBO trips, there is very little else it could be.
In the main when a boiler does trip a RCD on removing covers we will find a leak, so personally my first thing would be a service by a gas safe guy, which it likely needs, and hope he sees the problem.
So
or clamp on ammeter 
to find out what is tripping the RCD, but also need to test the RCD with a special RCD tester, and even going for cheap as shown above we are looking at around £70 for the pair, and £200 for RCD tester, so you can understand why plumbers don't tend to have them.
It could be the motorised valves in some homes where heating for some unknown reason it split upper and lower floors, or even a thermostat, so start by giving more information about your system, and the fault.
1) Have you unplugged (not just switched off) any other items using same RCD if it is the RCD tripping?
2) How much is on the same RCD.
3) What make is the boiler?
4) Does it trip when only supplying domestic hot water.
The more you tell us, the more likely some one will work out likely faults.
The problem is made harder due to gas safe rules, Electricians will have all the tools of the trade, but may not be allowed access to the boiler, where a plumber may have his gas safe registration but may not have the tools required.
In the main heating and ventilation engineers span both trades, but here in mid Wales hard to find, so what we want to do is guide you to finding out if really the boiler at fault.
So with my house very little uses same circuit as boiler, and it is oil anyway so no need for gas safe guy, so when my RCBO trips, there is very little else it could be.
In the main when a boiler does trip a RCD on removing covers we will find a leak, so personally my first thing would be a service by a gas safe guy, which it likely needs, and hope he sees the problem.
So
is likely wrong, likely no test gear will be required, likely the guys eyes will be enough, but the right test gear can destroy the boiler if used without the skill to know how, in the main we use an insulation tester
or clamp on ammeter to find out what is tripping the RCD, but also need to test the RCD with a special RCD tester, and even going for cheap as shown above we are looking at around £70 for the pair, and £200 for RCD tester, so you can understand why plumbers don't tend to have them.It could be the motorised valves in some homes where heating for some unknown reason it split upper and lower floors, or even a thermostat, so start by giving more information about your system, and the fault.
1) Have you unplugged (not just switched off) any other items using same RCD if it is the RCD tripping?
2) How much is on the same RCD.
3) What make is the boiler?
4) Does it trip when only supplying domestic hot water.
The more you tell us, the more likely some one will work out likely faults.
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