burner keeps burning with Heating off and DHW Off?

[Musa]

Vaillant VCW GB 242 EH - burner keeps burning with Heating off and DHW Off?

DHW works fine, Boiler on with tap opened, off with tap closed, but reignites after a few seconds on low flame with CH switched off. As soon the power is applied to the boiler the CH pump comes on the fan runs and the boiler ignites on low flame with thermostat in the off position. Help!!

 

[Gasman1015]

Possible faulty microswitch diverter valve.

 

[Musa]

Vaillant VCW GB 242 EH - burner keeps burning with Heating off and DHW Off?

Hi gasman
Checked the microswitches on the diverter valve and all the pipes to the diverter valve all o.k.
Before, the boiler on low flame and the pump, kept running even when the CH was not selected and the DHW was off. Now, after cleaning the diverter valve and the pipes connected to it, the DHW works fine as before but the boiler does not fire up when it did before but the pump still keeps running.
Can you guide me further as to what else it could be?
Musa.

 

[meldrew's_mate]

Now, after cleaning the diverter valve and the pipes connected to it, the DHW works fine as before but the boiler does not fire up when it did before but the pump still keeps running.

Try bleeding air out of the main heat exchanger, bleed nipple at the top left of h/e.

Many people confuse the silver coloured, centrally mounted, water section with the rhs mounted diverter valve & switches