Occasionally I can't get hot water from my tap allthough the flow ramains the same, after a while when turning the hot tap on I get hot water. This has been happening for some weeks but is becoming more frequent.
The central heating is working correctly

Robert Jenner, March 2008

This common problem is usually caused by limescale gumming up the diverter valve. The reduced movement of the diaphragm causes incomplete diversion of heating from CH to HW and/or failure to operate the HW demand microswitch. This results in luke warm water or none at all. A quick fix is to first turn off the boiler and water inlet valve and then remove the flow regulator from the bottom of the diverter valve. Then carefully use a smooth ended 5mm dia. rod to push the diaphragm upwards as far as it will go several times to break down the limescale restriction. Replace the flow regulator, turn on the water inlet valve and boiler and enjoy piping hot water until it gums up again.

Chris Terry, May 2008

surprise suprise!!
i have got same boiler and same fault.
i am waiting for coverheat engineer.
presently no hot water- day one

SANJAY, April 2008

It sounds like the diaphragm has perforated, this will steadily get worse until no hot water

gary.wright53@googlemail.com, March 2008