Hello, I'm hoping someone may be able to help.
My combi boiler was fitted around 6 years ago, and after two replacement timers in the first year, it has since been totally reliable.
Well, reliable except for the continual need to top up to raise the pressure around once a week - no leak has ever been found in the ch system, so this has become routine, and not of huge concern.
However, a fault has developed - I am only getting luke warm water. For around a week now, with heating on or off, my water temperature never lifts beyond this level.
Having read many threads on this website, I have given a hefty thump to the top right corner of the boiler whilst running the hot tap, and this has worked on two of the three occasions, providing a chenge to the sound of the boiler, as though firing a further cylinder, and providing HOT water.
I cannot keep doing this however, as I may get a sore hand!!

Many threads seem to suggest changing the DHW thermistor - is this likely to be the solution?

I've seen these on ebay for 6 -7 pounds, or a clip on type for around £25. What's best?

Oh, and finally, any suggestions for the water loss/ reduced pressure would be gratefully received also.

Thank You

Geoff, March 2010

Hi my c/h is ok ,but my hot water is luke warm,there is a small amount of water where the releaf valve is on the top

steve. sw, April 2010

new diverter valve or diaphragam kit required

dje, March 2010

Hi Ian, I've looked up the sealer and found Fernox F4. Is this suitable, and if so, how do I get it into the system?

How do I determine if I do need a new air pressure switch - can I test the existing one.

Thanks so much for your assistance.

Geoff, March 2010

may be a faulty air pressure switch.
as for the water leak if you can't see anything you could try adding a bottle of leak sealer. make sure the expansion vessel and pressure relief are ok.

Ian, March 2010