Potterton Gold 24 HE pump runs but radiators gold (intermit)

[ritchiehicks]

Hi,

I have a Potterton Gold 24 HE with an intermittent fault on the CH side. I'm quite a handy DIY'er but not plumber so please bear with me.

When needed, the wirelss thermostat sends a signal to the boiler to switch on the heating. Nothing wrong their. The pump will begin to run, the boiler fires up and then at some point seems to get "stuck" with the boiler not heating and the pump constantly running. The heating side goes off (the light which indicates the flame goes out) but the pump just runs and runs and will continue to do that until I intervene. I reset the boiler (hold the power switch for a minimum of 5 secs), switch it off and switch in back on again.

After doing the above, the boiler will behave from anything from a few days to a few weeks.

We have no other problems - when the radiators heat they all heat very well with no cold spots on any of them and there is no problem with the hot water.

I flushed the system in December after fixing a leaking towell rail in the bathroom, and added new inhibitor at the time. The system is approx 4 years old. I have bled all the radiators a number of times - no air - and the CH pressure is as per the manufacturers guidelines.

Any advice on this would be appreciated.

Thank you.

 

[Agile]

It sounds like an intermittent PCB fault.

But it could also be a temperature sensor.

Without monitoring equipment it could be difficult to identify the problem.

Have you ever had the boiler serviced?

Tony

 

[ritchiehicks]

It sounds like an intermittent PCB fault.

But it could also be a temperature sensor.

Without monitoring equipment it could be difficult to identify the problem.

Have you ever had the boiler serviced?

Tony

Hi Tony,

Having followed the troubleshooting guide in the back on the installation manual, I was thinking the same. I've had the PCB cradle open and checked all the connections. All seemed OK. I guess changing the temp sensor might be the cheapest way to go?

I haven't had it serviced. To be honest, I'm concerned about someone trying to rip me off on the cost. What should a service cost? Any advice on this?

EDIT: Oh, and I have a voltmeter if that's any use in fault finding?![/b]

 

[Agile]

Trouble is immediately you disconnect a temp sensor you could be disturbing the fault.

I suppose you could connect two wires in parallel with the temp sensor and measure the voltage across them and learn what voltage to expect at different boiler temps. It will probably be about 5-10v. If its low then the boiler will stop firing because it thinks the boiler is hot enough.

Or rather than resetting next time, measure the resistance of the sensor quickly. You may find that disconnecting and reconnecting it will make the boiler go again.

You are unlikely to "see" a fault on the PCB.

Tony

 

[ritchiehicks]

Trouble is immediately you disconnect a temp sensor you could be disturbing the fault.

I suppose you could connect two wires in parallel with the temp sensor and measure the voltage across them and learn what voltage to expect at different boiler temps. It will probably be about 5-10v. If its low then the boiler will stop firing because it thinks the boiler is hot enough.

Or rather than resetting next time, measure the resistance of the sensor quickly. You may find that disconnecting and reconnecting it will make the boiler go again.

You are unlikely to "see" a fault on the PCB.

Tony

Thanks Tony. That gives me something to go on.

Does disconnecting the temp senor (i.e. no resistance back to the PCB from the sensore) make the boiler 'think' it's cold (hopefully firing it up), or does low resistance = hot water?

 

[Agile]

Disconnecting the sensor makes the boiler think there is an open circuit sensor and will provoke a fault indication.

The sensor would need to be low resistance to make the boiler think its already hot. Unless its wet that would be a very unusual fault.

Usually a PCB fault. Probably an extended anticycling time delay.

Tony

 

[ritchiehicks]

Disconnecting the sensor makes the boiler think there is an open circuit sensor and will provoke a fault indication.

The sensor would need to be low resistance to make the boiler think its already hot. Unless its wet that would be a very unusual fault.

Usually a PCB fault. Probably an extended anticycling time delay.

Tony

OK. Thanks again for you assistance.