Vaillant Ecomax boiler: HELP PLEASE

15 Nov 2007
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United Kingdom
Just asking for some advice. We have a Vaillant ecomax boiler fitter in 2002. The past week we have had big problems with it. The hot water and Central heating are very temperamental. From looking at the boiler display, the temperature keeps dropping and then the boiler kicks in to raise it but then it drops again, so no hot water...or rarely very hot water and the central heating luke warm at most! We have restarted it many times and topped it up and still showing F23. Any ideas what we can do or what it may be?
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Most people call a competent boiler engineer when their boiler fails!

The F23 fault code probably means:-

Lack of water
Temperature spread too large
System not bled properly
pump jammed, reduced output of the pump,
air in the appliance, system pressure too low,
supply and return NTC mixed up,
appliance not filled via appliance-internal KFE **** (fill only via return!),
start venting program

What are you going to do now?

You need to check the flow and return ntc's and the pump.

Also check the auto bypass valve is not stuck shut.
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Check your motorised valve, i had the same problem your explaining, also for a quick fix i would usually have to reset the cylinder thermostat back to the middle which was the tempreture i wanted, basiclly my cylinder wasnt telling the boiler it needed hot water. As i said my problem was with the motorised valve i changed this and had no problems, shouldnt cost more than 70 for labour and whatever the cost of the valve, luckily i had a spare.

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