I had a similar problem. if you are able to dismantle the shower unit, you will find a flow filter inside the inlet elbow assembly - see parts 26 and 28 here
http://www.showerdoc.co.uk/shower-spares/triton/Combi%20HP%20Thermostatic%20Mixer.html
Ian
March 2008
have you any isolation valves on the shower pipework that may have been shut.
hi-spec plumbing
March 2007
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