Vaillant Turbomax hot water fault

[microlight]

My Vaillant Turbo max 282E combi (new 1997) will supply hot water when the boiler is cool/cold, but when I turn the hot water off and on again it wont start. It needs to cool down for a long time (hours) before it will supply hot water again, however when the hot water is on it will stay hot (doesn't run cold) until turned off...then wont restart...very annoying. Only one shower in the morning in the house, unless you leave the hot water continuously running...

Any ideas would be greatly appriciated..Martin, Brighton

 

[Agile]

That seems at first sight as rather unusual.

The diverter valve usually fails after three years and the APS a few months later.

To help diagnose I would ask you to try the heating when it works on DHW and when it doesn't a few times to see if there is any correlation.

Its an unusual fault but the temperature sensors may be failing.

Its only a guess as I have not done any diagnostic tests but the APS would be my best guess at this stage with minimum info.

Tony

 

[microlight]

Thanks Tony.

Just tried it. If I turn on the DHW for a very short while it will restart again but if i let it run for a few minutes till the water gets quite hot it wont restart. If i then turn on the CH and then turn on DHW it will supply DHW. Turn off the CH and DHW, then turn on the DHW only and it wont start. Fault seems to be just with the DHW when the boiler is hot.
Martin

 

[ChrisR]

Temp sensor/thermistor/NTC (all names for same thing) sounds likely.

 

[Agile]

I still dont really know if the CH works all the time when its called for.

It does sound from what you say that selecting and running the CH does have an effect on the DHW though!

That model has TWO temperature sensors and their tracking is relevant to the operation.

I still suspect it may be relevant to the diverter or APS as they are very common problems with that model.

Tony