Any plumbers about!? Franke Minerva tap

[Grobag]

Quick query, got a Franke Minerva boiling tap and water has started flowing through the tundish. The manual says it's a pressure release, and blows if the pressure exceeds 5 bar. It's fitted with a pressure reducing valve on the incoming supply so I'm assuming it isn't due to high mains pressure. The bit I'm confused about is its boiling water running through the tundish, and the cold feed pipe between the tank and the tundish is also hot. Anybody got any ideas on why boiling water would go against the flow and reach the tundish? Thanks.

[Grobag]

Thanks for the reply. No new isolation has been introduced since it was installed. I turned it all off to let it cool then did a filter change. Turned the water back on but not the heater on yet as water is flowing through the tundish again. Not sure how the release valve works but I would have thought that once the pressure is released the valve would re-seat and be good to go again? Think for the time being I'll isolate it and call the installer!

[Grobag]

Thanks. Yep as soon as the cold is turned back on it flows through the tundish which I assume means either the pressure release valve is a one-hit wonder or its somehow got stuck open. Either way it sounds like a replacement is needed, I'll get a plumber to take a look. Thanks for your help.

[Grobag]

Thanks for the heads-up Richie. Spoke to the plumber, he reckons that its just scale caught under the seat of the pressure relief valve, as it should close automatically once any pressure build-up has been released. So hopefully just a bit of TLC to the valve should sort it rather than a whole new tap!

[Grobag]

A conclusion to close what was always gonna be a fairly dull thread! Turns out it was a faulty pressure release valve, the seating that the washer sits on was incomplete and after a while the sharp edges lunched the washer.

Not sure why it was hot rather than cold water that was coming out, can only think that the tank pressure was higher than the pressure that the reducing valve was set to. Still, no worries, a new valve appears to have sorted it, so another job off the list!

Thanks to those that replied.