Went to a repair this morning on an ariston microgenius 24mffi, E34 error code showing, the cust had hot water only for a few seconds before the boiler cut out and the heating was only working at a low temp. I suspected sludge/debris in the heat exchanger and plate heat exchanger. I had replaced the aps a couple of weeks ago which had cured the problem. I was at a loss as to why this error code had reappeared as all the usual checks showed everything working ok and having power. I phoned the ariston tech helpline ( what an attitude on the guy, Im sure he wouldnt have that attitude to my face, must have been his time of the month) they suggested there may be a flue restrictor present that could be removed and that I should clean the fan blades. I duly cleaned the blades and removed the restrictor. This solved the problem with no hw and the ch went up to temp, however in ch mode the boiler still intermitantly shows E34 error code, although it still seems to work when the room stat is turned up and down, and when hw is called for everything works fine. Has anyone had any experience with ariston boilers that could shed some light on this? or should I go with my first instinct and tell the cust to buy a new boiler as aristons are so very.......quaint