you will need to get a new "pressure relief device" from triton.
they cost about £8.00. your shower head is probably the cause due to a build up of limescale. clean this before you you turn the shower back on!!! i think viakal can be used for this. here is the web page you need.....http://www.tritonshowers.co.uk/wps/wcm/connect/TritonShowers/Internet/Spare+Parts/
the doktor
October 2006