I have found my kitchen hotwater tap has seized/bocked as no water comes out (other hot taps are fine). Tap turns out but get no more than a tiny dribble.

While trying to turn off the cold feed to the HWC, (so that I could repair the tap) I found:
a) I couldn't turn either of the valves in the photo. Just won't turn. The Red handle is loose with ~5mm play/wiggle but the lever it would otherwise turn will not move.
b) I don't know what the black plastic-topped valve/device is. Can someone explain?

This is all around a corner in a very narrow cavity at the back of the cylinder cupboard so I can't actually see in there. This photo was taken at full arm length around a corner in a cupboard.

The HWC is low pressure, as it is feed by a header tank I have seen and heard in the roof everytime we run hot water. The water filling the header sounds quite high pressure.

The vertical section closest to camera is header tank -> HWC bottom feed

I don't know what the pipe heading up to the black plastic/brass device is, or what the brass pipe is curving up and away.

In the downward aiming photo, the brass pipe below the junction is just a wetback return.

Hoping someone can help me answer some of these questions? Cheers


Linkback: https://www.plumbers.nz/q-and-a-valves/49/valve-identification/1210/

Hmm, seems to be the night to solve your own problems by answering your own stupid questions.

I got the valve to turn by trying harder. yep.

I'd been warned not to break or damage valves like these so was being extra gentle.