Pump only turns on when temperature lowered

[Fudgie]

Hi,

I have had a new shower/bath installed with a Kusasi lever thermostatic three way valve (3 levers, one for shower, one for temp, one for bath).

Each morning the shower/pump does not turn on when I turn the shower lever, but if I lower the temperature lever or turn the bath lever the pump springs into life and works fine.

You can then turn the shower on and off with the shower lever without any problems, but after a few hours of inactivity the problem returns. Once again I lower the temp or turn on the bath lever for a second and the pump/shower springs back into life.

Any ideas?

Thanks