Biasi 24S Combi

This boiler is approximately two years old.
Although the central heating is working as normal, there is no hot water being produced. The flow of water is normal but is not being heated, although bizarrely there does seem to be hot water produced for two or three seconds when the tap is first turned on.
Perhaps this is a known fault with a obvious solution. Many thanks if anyone can advise

yes its the diaphragm split in the diverter valve on the left hand side....needs replacing

Many thanks Ollski for your reply.
My apologies if these next questions seem stupid.
Having looked at the diverter valve I see that there are two diaphrams, a big one and a small one. Will it be one in particular or could it be either. It looks as if replacing the bigger one would be more involved, would I need to remove the diverter valve from the boiler?
It looks like the smaller one (facing forward) could be easily replaced.
Do I need to empty the boiler of water completely ie central heating system as well? Thanks again

Yes its the big one, bit awkward but not too bad.Turn off your mains stopcock and open all your hot water taps to drain the hot water side of the boiler...leave them open until you refill. There are 2 circlips on this one holding two small tubes...you need to take the circlips off and remove the tubes, probably get a bit of water flow from the taps now and a bit of a dribble from the pipes. Now you can undo 2 small grub screws on the valve body behind the diaphragm housing and pull the housing off. When you've got it in your hands you can unscrew all the screws and replace the diaphragm. Just reverse it all to put it back. The only time you will need to drain your heating side is if the valve has been passing, but then the whole valves requires replacing anyway.

i visited a biazi combi last week with the same problem, turns out it wasnt the diaphram, it was the dhw temp sensor, thinking it was up to 60 'degree's in about 10 second's then shutting the boiler down. check that also

Many thanks for the replies. The boiler is now working properly again for the cost of a new diaphram. Replacing it was very easy, when you know how. Thanks for your concise and clear instructions Ollski.

Hi
would appreciate any help on this one. I have a biasi 28s boiler and have had problems with it for two years now. When i first moved in the boiler had no hot water working and would not fire up.I replaced the heat exchanger and it worked for the next 9 months. Then it started tripping out on the cut off switch and when you pressed the switch it would then fire up When i took the heat exchanger back out there was loads of particles in the central heating side of the exchanger and i cleaned the exchanger out with ds 3 When replaced it ran fine. Now tho in the morning when you turn the hot tap on the boiler does not fire up i have to run the central heating then turn the tap on and it switches over and you have hot water, sometimes tho the lock out switch comes on as well tho Am now getting with it so any help would be excellent Someone said it could be the diverter valve or diaphram etc Thanks

Please start a new thread rather than highjack an old one.