Microgenus HE 24 MFFI Domestic HW Hot and Cold

[lexx]

HELP
Domestic hot water running hot then cold?
When turning on the hot tap boiler fires up temperature starts to rise After a minute or two reaches 40 dec C and the boiler cuts off. Panel shows error code E33 after a few minutes the error code goes off and the boiler fires up again. Boiler continues to cycle on and off. This also seems to happen to the central heating. I have had the air pressure switch replaced and the flame sensor electro cleaned but the fault remains.
Any ideas what could be the fault.
Any suggestions would be appreciated

 

[Agile]

IF, this model of the microgenus has a plate secondary heat exchanger then its probably blocked with dirt from the radiators.

Tony

 

[lexx]

Hi Tony

thanks for your help will check the heat exchanger.

cheers
Gary

 

[zk]

E33 error code has nothing to do with the plate heat exchanger. The original post says that the boiler comes on and goes off in both hot water and heating demand. If it was the plate heat exchanger the temprature would go a lot higher than 40 degrees befor it cut out. Your problem is linked to a flue/aps issue.

 

[petit_pablo]

The OP has changed the post from what was originally posted. There was no mention of E33 when first posted

 

[Agile]

He must be deliberately trying to confuse me by changing the symptoms AFTER I have done my diagnosis!

Tony

 

[lexx]

Tony

Sorry about the confusion i first wrote the symtoms down rough on scrap paper I am not very good with typing and before I had input all the information I must have pressed the wrong button and the post was submitted before completion. I then had to re edit and include all the symptons of the fault.
regards
Gary

 

[lexx]

Hi
Decided to call Ariston engineer in. He removed the fan and cleaned the blades. FAULT CLEARED. He said on this model of boiler it is important to clean the fan regularly. Being interested and inquisitive i just dont understand why the pressure switch would signal a loss of air pressure and shut down the boiler, when it appears to be running at constant speed, And when observing the boiler this seemed to happen around 40C. Anyway,Worse things happen at sea. I was just happy to have the boiler up and running.
Thanks for the help.