Zero pressure in Range Tribune HE

Hi there, just moved into a new flat and we don’t get any hot water unless the immersion is on.

I’ve checked for two black capped valves to open to increase pressure but can only find one valve and opening this does nothing. There are a couple of red capped valves that do open and water runs into the tank when opened, but pressure stays at zero. Can anyone help?

Tribune is just the hot water cylinder..it has nothing to do with the pressure gauge.

Please don't tell us you've turned the red capped safety valves...they rarely shut and often need replacing if so as they will constantly drip.
What you are hearing is the water discharging into the tundish (the small black tell-tale) device.

Take out the little screw in the black lever on the braided hose filling loop and see if the lever actually turns the spindle...often the plastic lever splits.

The screwdriver slot isolating valve is at the other end of the loop..it's currently open but should normally be left with the slot across the pipework.

Be aware that both the red and white expansion vessels require yearly maintainance.

Stop playing with the red valves as you call them