Truma valve jammed open - help! On the road in Scotland

[Landy Andy]

Just turn it. If it’s “warm” there it won’t be frozen just stiff.

 

[Lenny HB]

if you look closer, at about 60% of the way through the video, i think you can briefly see a round pipe exiting the floor and the waterfall effect is being caused by the water from that pipe dropping onto the vehicle skirt, making it look worse that it is .....

You could be right, difficult to see on a phone.
If that's so it would point to a buggered valve.

 

[Bramidan]

As others have suggested do the simple things first.
Hot water bottle around the valve and leave it to get warm
You will then have eliminated the dump valve working because it is too cold.

 

[Landy Andy]

Even if cold enough to activate the knob on the top still turns. Just the button on base won’t stay in. The knob is stiff because it is working against a spring.

 

[royandsharont]

if you look closer, at about 60% of the way through the video, i think you can briefly see a round pipe exiting the floor and the waterfall effect is being caused by the water from that pipe dropping onto the vehicle skirt, making it look worse that it is .....

If you look & pause it on a tablet there does not appear to be water coming from the drain pipe, which looks just like mine so I think it is the dump pipe

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