How to replace Vaillant ecotec plus or Vaillant ecotec pro diverter valve or three way valve

Replacing the Vaillant Ecotec combination boiler diverter valve : How to isolate water supply, drain the boiler and remove the old diverter valve, replace the diverter valve with new one , turn the water drain points off and refill the boiler and commission the hot water and the heating,

[@crashnburnband]

Thanks that's useful I have one of these to do today