Changing a tap microswitch

[wildebus]

Do what now?

Also known as an Expansion Vessel (that's what I call them ).

Expansion tank - Wikipedia

en.wikipedia.org

Where you have a system that does what yours does and there is no actual fault, these can eliminate those annoying glitches of pump activity.

I fitted one as part of my plumbing in the last camper.
Clarence Water System by David, on Flickr
They are small, inexpensive and and added bonus is if you open the tap a little way, the pump might not need to come on (so can use the bathroom tap or even flushing the loo without the pump powered)

 

[Pudsey Bear]

It's a vessel in the pipe line to take out pulses and can help wit the BRRR at night.

Google it sir.