My power shower decided to turn itself on in the middle of the night! At first the pump was just humming for a minute or so, but no water. Then the pump was going and water coming out - on and off all night. No switch in airing cupboard so guess that'll be in the loft then! Managed to flip the fusebox switch off last night to shut it up! Will be up in the loft tonight to switch off up there. Anybody know what is causing the problem and if it's easily fixed? Thanks.

(Had a look on Aqualisa site - its the aqualisa aquastream theromstatic and manual integral power shower 1997-2003) (Oh and the shower is working normally apart from that!)

Emily, January 2010

I should be a bit more specific about the microswitch and why it causes the problem. The microswitch is a tiny switch operated by a very light touch to make the inner contacts make and break. When you turn the shower on, a cam (or raised lobe) causes the contacts to make and so turn the pump on. When you turn the shower off the reverse happens, the contacts break and stop the pump. Pump run on means the contacts are sticking together regardless of the position of the control knob. The microswitch cannot be dismantled and the only cure is replacement of the microswitch/rectifier loom assembly. The microswitch is not available as an item. It doesn't take much in the way of debris or wear to make it malfunction. The run on of the pump means that the contacts have become sticky and won't separate.

Denis.H - Folkestone., February 2010

Thermostatic loom assembly 168520 NOT 168320 -sorry.

Denis H.- Folkestone., February 2010

Microswitch behind the control knob is faulty. This lets the pump run on even when you turn the water off on the control knob. Your unit can only be a manual or a thermostatic not both. Aqualisa part numbers are 178322 for the manual and 168320 for thermostatic. Note that if it can do this then that means your transformer unit that supplies the low voltage is connected to mains all the time. Even these low voltage showers benefit from a switch in the mains connection to the transformer so you can turn the system on/off before and after your shower. That means the transformer doesn't remain permanently powered.

Denis H. - Folkestone., February 2010