Hi Sophie , It could be a number of things but try the simplest first. Always have a competant/ qualified person check an electric shower. Unlike any other shower the advance requires a commissioning process before you can use it. Details are in the instructions. A lot of people dont bother and the shower operates, but not properly. The Advance is a very sensitive unit and it likes a constant flow of water. The first thing to check is the filter situated on top of the water inlet. You dont say how old it is but the slightest bit of debris in there will cause problems. No one ever cleans them. Also on top of the flow valve you will see typically a blue button. When commissioning this should be depressed with the power off so that air is purged from the tank. During this process you will get some water running down into the unit and this is normal, just make sure its dried off before continuing . Sometimes the Wiring loom or long ribbon that connects the front cover to the unit has not been fixed poorly , make sure non of the pins are bent. Please get a competant or qualfied person to check this.
Alan, December 2008
