Help. Frost valve on 2016 Frankia i7400

[OldCodger]

It’s me again!

Over winter the frost dump valve on the water system has trip. I saw water running and turned the pump off. Pulled the plug in tank and left it.
I just came out to sanitise the plumbing and the system won’t pressurise. The pump keeps running. I guess the frost valve has stuck. Does anyone here know Where is it so I can reset it?

 

[Lenny HB]

Can't help with your particular vehicle but it will somewhere near the boiler normally with access via an outside hatch.

 

[OldCodger]

Found it. Buried under the bathroom sink! Hidden behind the panel and reset via a hole in the bathroom cupboard!

Thanks for trying to help!