I've an Aqualisa Aquavalve 200 shower mixer unit which is leaking at the shower head. I've been told that it can be either the thermostat .cartridge or a small rubber 'o' ring at the back of the cartridge that is leaking. The cartridge costs around £80 to renew so naturally I want to try a replacement 'o' ring first but I don't know which one to buy. Can anyone help ?
Thanks