Halstead Best 80 pump intermittent

[katelev]

This boiler failed last week and a faulty Aquastat PCB and Thermistor was diagnosed and replaced. It then appeared the fan was faulty also (possible cause of Aquastat failure?). This was replaced today.

We are told by Halstead it needed to run for 15 mins before the pink wire was reconnected. However, there seems to be an intermittent fault with the pump operation. Power is intermittent and it cuts out, which then causes the boiler to overheat and shut down.

There was quite a bit of air in the system much of which has been expelled, but we can't expel all because we can't get the boiler to run long enough.

Can anybody shed any light as to why this is happening as we believe the pump is functioning correctly. Are there any pointers as to where the possible electrical fault lies?

Many thanks

 

[JohnKay]

Hi katelev
Correct me if I'm wrong, but I asume your system is controlled by one or two motorised valves, and the pump is external to the boiler.
The boiler is supplied with a permanent live connection, a switched live to fire the boiler on terminal 1, and the pump supply on terminal 2

As the boiler overheats, we know the supply on 1 is OK. We need to know if the supply from 2 is at fault, indicating a fault with the aquastat or temp control, or even a bad connection in the boiler.

If the connection 2 could be tested it may eliminate an external fault, or the pump itself.

As I don't know if you are able to safely check this youself, I cannot advise any DIY work that involves live testing.