Vaillant boiler leaking

[Harleybear]

Hello,
My boiler leaks from underneath the boiler once I put on shower/hot tap or heating. Then it will lose pressure completly. What could this be?

 

[Wayners]

Could be coming from anywhere. Open up and look

 

[Stuckinarut]

Depending on which Vaillant you have, could be a failed condensate hose, which could be dangerous. I wouldn’t advise opening up the boiler, best just getting a gas safe registered engineer.

 

[spile]

Failed o rings, diverter valve, heat exchanger…