phlexiflow shower waste flow switch problem

[uxlet]

I am hoping someone out there has experienced something similar to this problem. I installed a phlexiflow high flow waste system to a shower (basement flat). All works fine until I switch off the shower and the 2 flow switches (vertically installed just before the power shower) stay closed and keep the waste pump running.
I have unscrewed both switches and checked for free movement. All seems ok.
I was wondering if anybody has had a similar issue. This has got me stumped !

The kit was installed as per instruction and the manufacturer had no idea.

 

[Charnwood]

They are supposed to 'run on' for a short while after the shower is shut off to allow the shower tray to drain fully.
Is this what's happening, possibly?

 

[uxlet]

Thanks for applying your plumbing brain to this one - The waste pump definately 'runs on' after the shower is shut off. It just does not stop. When I put a meter across the flow switch to investigate the problem, it was displaying a closed circuit - and I left it for several minutes before switching off at the mains to avoid running the pump dry.

 

[Charnwood]

If it runs on and on and on and on and on and on and has been fitted correctly, then something is probably faulty.