Ariston Eurocombi A23MFFI Hot Water Problem

[hadriz]

I have an Ariston Eurocombi boiler A23MFFI with hot water problem. The problem started if you selected hot water only, there wouldn't be any hot water coming out of tap. If you selected central heating and hot water, the hot water would work fine. It then got worse, no hot water with either selection. I got an engineer out and he said it was the diverter valve. The pin in the valve is not coming out enough to engage the micro switch. He changed the valve, and now the pin is engaging the micro switch but the water goes hot and then the boiler shuts down too quickly, he then changed the temp. sensor on the diverter valve but with nothing changed. Now he tells me it could be the pcb. Can anyone help please.
One thing I noticed after the diverter valve was changed, the boiler is noisy every time it starts, for about 5 to 10 secs only.
By the way central heating works fine apart from the noise mentioned above.

 

[frankthegasman]

the fault could be a partially bloked domestic hot water heat exchanger,good luck

 

[hadriz]

Thanks for your reply.
I understand from reading similar problems in the forum, there may be 2 heat exchangers for this boiler. So which one is likely to be the partially blocked one.
Does anyone have a service manual for this boiler, if so, could I please get a copy by email. Many thanks

 

[Agile]

Its the plate HE at the back low down.

You can confirm that its blocked because the temperature differential across the boiler in DHW mode will be too high. It should only be about 15-20°C if its clear.

Tony

 

[hadriz]

Thanks Tony for your reply. Any chance of a copy of the service manual please.

 

[Corgigrouch]

From memory the secondary HEX is the grey cylindrical object that butts up to the diverter valve.. Sounds like it has a blockage in it as has already been said.

 

[Agile]

I think its a plate on this model!

There are about eight different boilers each called Eurocombi !

Tony