In reply to message posted by johnws:
How new is the installation? Has this just started happening? There is a pressure loss in the plumbing somewhere and you can fix the shower as suggested by Sylvan and/or find out what is causing the loss. It may be a resriction in the line or the reducing valve may not be capable of good flow to overcome some of the pressure loss.
John,John, John PLEASE READ THIS AGAIN ok Mate?
“Now if you really want to protect yourself and your loved ones consider spending a little more money and get not only a pressure balance type BUT a temperature control also.”
I know your from Australia and your codes are very lax as illustrated many times on here so it is not your fault.
If you see I put TEMPERATURE and PRESSURE balance
which means I could careless what pipe restrictions are present as A QUALITY Made tap will allow for BOTH T&P fluctuations ok mate PLEASE feel free to join my list to get a REAL education in plumbing and protecting the people.