Vaillant Eco Tec Plus 825 no hot water, heating working fine

Vaillant Eco Tec Plus 825 combi boiler, installed around one year ago developed a fault where it would not fire up for hot water. Boiler worked fine in heating mode but would not react to turning hot water on.

Below video show the boiler under fault conditions followed by short video of boiler after repair operating correctly in hot water mode.

Repair required one new spare part and took no longer than 15 minutes. Failures like this are rare on brand new boilers but as we can see here they can happen.

Boiler not reacting to how water demand before repair: (Hot tap is on but boiler does not see a request for DHW)

vaillant boiler repair

Boiler after repair showing hot water demand on display and firing up.