Vaillant boiler timeswitch problem

[gemius]

I have a Vaillant ECO max 828 E boiler.

Everything works fine but the only way to control the central heating is via the thermostat.

If I leave it to operate on the Time Switch it turns itself back on on at some point even though the Timer is telling it heat is not required.

I've fitted a new Timer but it has made no difference.

Any advice on this problem would be appreciated before I call in an expert.

 

[bobw1956]

Have you got the warmstart/preheat,set on the display on front of the boiler,if so the letter "C" will be showing, turn this off

 

[The831Bunny]

If you mean your heating is coming on when the timeclock is off, then it's a high possibility that the diverter valve is sticking and requires replacing.

 

[Bunnyman]

+1 mr 831

 

[gemius]

I don't have the pre heat on bobw1956. I could never see the advantage unless you were drawing hot water off constantly.

Thank you Thebunny831 I'll look into that. Might have to just change it and see. The boiler is quite old now.

 

[gemius]

I'm still considering my options here.

I'm not 100% sure about how a Diverter valve works but if I'm getting domestic hot water and heating when required. Which I am. How can the Diverter valve be faulty?