What is this thing coming out of a Heat Interface Unit and why does it leak?

There's a flexi hose in the video with a screwdriver isolation valve on the end of it. The camera moves too fast for anything to be in focus but best I can make out is the valve head is at 90 degrees to the pipe, ie the valve is turned off.

Theo

It could be breaking the Water Regulations, but, if there is a check valve on the loop, and another check valve on the incoming supply, then it would be very hard for there to be any backflow, so almost impossible to break the Water Regs.

Page 21 of the installation manual shows the connections. It is the condensate. The PRV should be copper until it reaches a drain point, or goes outside. Page 12 of the installation manual.

That doesn’t fit with the OPs photos. Tun dishes aren’t fitted to condensate drains normally.

Tim

Am I the only one puzzling over “heat interface unit”? I haven’t a scooby what this means.

Tim

In the video the drips of water are clear. Could the brown discolour be a mould on a fitting that has remained damp for some time.

In a building such a tower of flats, there's a central boiler with hot water loop, and each heat interface is a heat exchanger with a heat meter for billing (based on flow rate and temperature difference).

But that’s not what the OPs picture looked like. It looked like a standard combi or system boiler.

Tim