Refilling the air gap on a megaflo.. please help!

[Jim8]

So I’m trying to refill the air gap as per the inscructions on the tank but I’m struggling to locate the mains cold water supply valve/knob. Can someone please explain this to me like I’m a complete idiot lol. Our megaflo is on the first floor of the house.

Which of these in the picture do I turn to shut off the cold water supply?

 

[cdbe]

 

[cross thread]

Looks like a blue tap on the left

 

[oldbuffer]

1. It the valve with the black handle highlighted with a red arrow in cdbe's response.
2. They are often very stiff to turn. If this is the case you can always turn the water off at the main stop-cock. If doing so, switch the boiler off as well.

 

[Jim8]

Thanks for the replies guys. So I figured it was that valve on the left but I just wanted to make sure

So with that valve shut off, is there supposed to be cold water coming out of the taps still? Because there is