The boiler (about 7 years old) loses pressure quite regularly and I now know how to increase this, but I am having to to it more often. The shower can be lovely and hot one minute and then goes stone cold. It used to get hot again after a few seconds which I understand is all to do with the pressure, however, now I am flicking the heating on in the mornings this seems to affect the hot water flow. It will be hot, goes stone cold after a couple of minutes and then does not get hot again - pilot light goes out. Why? It is not so bad if I don't put the heating on first but still occurs. My plumber said he cannot fix it whilst the boiler is working! (Yes, I am going to change my plumber.) I then have to keep flicking the ignition switch backwards and forwards to get the pilot to light again which is getting more and more difficult to do and then the same problem occurs. Any ideas?

Anne Gray, October 2010

if its not that the most likely the below the heatex is blocked

kash, October 2010

hi i have worked on these boilers and fit them regularly my advice to yourself is to change the switch diaphragm washers as these go after around 5 years on these they are not expensive around 10 each i can work it out if i was there but am not but try these first as a little hole or wear will cause the water to fluctuate

kash, October 2010

the 105 like any combi is hot water priority so while youre hot tap is running youre ch wont fire till you turn off the hot tap.if ch is ok sounds like a blocked plate heat exchanger but could also be a problem with the diverter valve.any experienced gas safe registered engineer can diagnose this fault.

deano, October 2010

sounds like over heat
could be plate heat exchanger
or thermister

b, October 2010