Baxi 105e instant.
Diverting valve operating head keeps clicking on and off
Pressure guage building up pressure even in DHW only
Temprature goes up to maximum, no control on temprature
Hot water from tap runs hot and pulses cold.

Had replaced
Both Diaphrams
Both Microswitches
Cleaned filter

Help!!

MickH, May 2010

DHW or Primary thermistors could be going out of range, gas valve low gas not set correctly, blockage on the DHW heat exchanger, ignore this previous pos on here about leakage from Heaexchanger - Talking out of their A=se. Easiest thing is get british gas outone off repairs from |£99 inc part and labour for that fault

paul - qualified professional, May 2010

This sounds like a classic case of dhw heating exchanger failure. If system pressure is constantly increasing it can only get this excess pressure from the cold water mains supply via the exchanger.As you are also having hot and cold bursts out of your tap this points towards leaking dhw exchanger I would have thought.

Guytawe, May 2010