Hi all, our central heating water pump has started making a repeated clicking sound (you can hear it in this video clip https://tinyurl.com/trlcxxl for the first 10 seconds) sounds a bit like an electrical contact switching or a solenoid. This seems to happen before every time the gas boiler fires up, it clicks constantly every second for about a minute, then the boiler fires and it seems to run normally for a while. Then shuts off for 10 mins then the whole process repeats itself. We've asked a couple of local plumbers but they didn't seem to know what was causing it. Any ideas much appreciated. Cheers.