Waterpump running constantly when tank empty

[Hurricane]

@henry, thanks, and it wasn't egg-suck teaching - I know the principles but haven't changed one before. My main suspect is the tank membrane and the new tank has already arrived. All noted re the pressure set up though my hope is that I can just swap the tank and leave the pressure switch set as is - they're separate components. I'll see how it goes.

I think mine must be like yours.
The pressure switch is, essentially, part of the pump (fitted to the outlet side of the Gianneschi pump). The expansion tank appears to be a separate unit.

I have just checked my files and I seem to have a PDF file from Gianneschi who seem to provide these expansion tanks.
I've not read it properly, but this document has instructions on how to change and repressure the diaphragm etc.
If anyone is interested, maybe I can arrange a link to it.

 

[powerskipper]

Yup, and better to turn it off as I have seen them burn out trying to pressurise water when there is non.

 

[JerryC]

Thanks HenryF for post 59, a good example of how this forum can be so informative.

 

[henryf]

Thanks HenryF for post 59, a good example of how this forum can be so informative.

In my youth I built a 70 foot narrow boat so had to learn on the job with regular trips to the Uxbridge boat centre for all manner of strange fixtures and fittings

Henry