how can i fix my ariston eurocombi boiler a/23mffi?

all the above answers are NOT wrong? but you need to sort it out by elimination;the first thing to do,is bleed the rads with the system OFF;then try again;if this dont work,buy a temperature prob[£5]or less and fit[not difficult],the problem with the red light coming on i'm sure [80% ] is one of these problems;

pw
February 2011

my boiler over heat light keeps coming on and the heating and water goes off is it the thermostat
it stays on for about half an hour

LINDSEY WATSON
November 2010

Bought a house with an Ariston eurocombi boiler and I'm unable to set the timer. It does not appear to have a switch to set it. However there is a little hole where a small object can be inserted but I'm still unable to set it. Could you please help me

Sylvia
February 2010

what is the co-co2 reading?

yan
June 2009

i have posted answers regarding the diverter valve which goes faulty ever 2-3 years and given the level of knowledge shown i think the simplist formula is for you all to get breakdown cover for your boilers eg thames water or british gas (although i will say that a friend of mine had every part of his boilers replaced over 4 weeks by BG as their plumbers didnt know what they were doing so came back repeatedly).

RICHARD MOORE
May 2009

I had the same problem on my A23 mffi and traced it to the ‘Temperature probe’.

Google 'A23 mffi' and click on one of the Harrian.com links for the EuroCombi A23 mffi (currently the top two). Make sure you are looking at the correct pdf document for the serial number of your boiler. The part I'm talking about is ‘Part 20, Code 569236 Temperature probe (CHW)’ in the 'a_23_mffi_from_2320015700001_to_.pdf' file and it's ‘Part 18, Code 569236 Temp probe (C.H.W.)’ in the 'a_23_27_mffi_from_983610001_to_2320015700001.pdf' file. Since they are the same part Code in these two documents I assume they are the same physical device. There may be another pdf somewhere for other serial numbers not covered by these two files.

To check if the Temperature probe in your boiler is faulty do the following:

• Switch off your boiler at the electricity mains and let the central heating system cool down fully (if its been on – apart from avoiding scalding yourself I think this may also be important to get a proper reading from the multimeter in the 3rd step).

• Disconnect the wires to the Temperature probe (pull on the connector, not the wires).

• Connect a multimeter, set to resistance (kilo ohms range), to the electrical tags protruding from the probe. The resistance that registers on the multimeter should be 5 kilohms. If it is less than 5 kilohms it is faulty and should be replaced. The part Code has now changed to 998458 and should cost about £3.60 + p&p. Note, the part is also known as a Thermistor (i.e. a resistor whose resistance varies with temperature).

To replace the Temperature probe you will need to drain the water from the boiler itself only (not the whole central heating system). There is a small ‘drain’ tap on the far right hand side of the bottom of the boiler (near where the mains cable goes into the boiler). Stick a bowl under the ‘drain tap’ and open it up (from inside the boiler). Once you have drained the boiler's ‘head’ of water, undo the faulty probe with a spanner, replace it with the new probe and reconnect the wires' connector. You then need to top up your boiler with water from the cold water mains. There should be a ‘top up’ tap (valve) coming off the cold water mains pipe that provides cold water to the boiler for heating up for ‘tap water’. Opening this 'top up' tap will begin to fill the central heating water circuit of the boiler (i.e. ‘pressurising’ your boiler). In order to purge as much air from the boiler while water is filling it, leave the 'drain tap' open until water starts coming out as a steady stream. If you can switch off the ‘drain tap’ to cut off this steady flow then the boiler will begin to pressurise properly and hopefully all the air should be purged. When the pressure gets to about 1.0 bar (i.e. in the middle of the blue range on the pressure gauge dial) close the ‘top up’ tap. If you can’t close the 'drain tap' while filling the boiler close off the ‘top up’ tap and then close to ‘drain tap’. Resume pressurising as before by opening up the ‘top up’ tap. Stop when the pressure reaches 1.0.

Close up the boiler and switch on the electricity mains. If it isn’t already, set the ‘Summer/Winter’ switch to ‘Winter’ (the picture of a radiator and tap). If the time you’re doing this is not at the normal time your heating comes on then use the manual select button on the boiler’s clock (the hand with the finger extended) to cycle through the options to switch the boiler on to ‘constant’. If the boiler fires up then let it run for a minute or so until any ‘gurgling’ stops. Switch off the boiler and then go around to the radiator nearest the boiler and ‘bleed’ any air out of the radiator (any air left in the boiler will probably have made its way through the pipes to the first radiator). Check the pressure guage and refill to 1.0 bar if necessary. Later when the heating has been running for a while carefully (they will be hot) check each radiator in turn to see if there is any air in them (the top of any radiator with air in will feel cool compared to the rest of the radiator). Once all (any) radiators are bled you may need to re-pressurise the central heating system again.

Good luck and if this doesn’t sort it out apparently there is a simple way to check that the printed circuit board responsible for temperature regulation is also working.

Mike
January 2009

i have same problem but now orange light is on as well
had new board fitted 200.00 still not working

diane collins
December 2008

exactly the same problem with mine now!! Is it just due to air in the pipes or does it need a service done by a professional?

Many thanks,

AL

alex
November 2008

We too have the same problem!!! Please, let us know if you manage to get yours fixed.

ellie
September 2007

i had this problem on my euro combi sporadically for a year.. an engineer came and checked it over and sanded down the ignition pilot light and said something like it was dirty .. this worked for a couple of days and then it went back to red light madness.. i left it for while and started saving for a new boiler .. then i decided to drain my central heating system and refill... put it on high temp to get the pressure and heat up.. then carefully leaked all my radiators for air.. which there was quite alot.. the result is so far 3 mths with no red light.. this may help you..

james
December 2006

DID YOU FIND THE SOLUTION TO YOUR PROBLEM BECAUSE WE ARE HAVING THE SAME PROBLEM???????????????????

Abdurrahman Ozdamar
December 2006