Looking for help with a boiler valve/tap

[Rub]

I'm sure that this solution to my problem is very simple and that I am probably missing a trick.

However, I'm trying to increase the water pressure on the boiler in my flat for the first time since I moved in. In the past this has been done on the filling loop with a simple tap. This time I'm looking at a tap that I have not seen before. It looks like the tap you would find on a sink but it has a slot for a screw driver on the top. It looks like this only allows the tap to turn in one direction at a time and as a result I don't want to open the valve/tap incase I cannot shut it off again.

Does anyone have any experience with using these sort of taps/valve?

 

[clf-gas]

This is the the filling point.

With slotted screwdriver turn and increase pressure to 1bar or slightly above, then close so slot is back to 90`

 

[Rub]

Thanks for the response but it's not the filling of the system that is the main concern. Basically, it's the tap that you would use to do so. It looks like a regular water tap that you would find on a sink - a round knob. However, unlike a regular tap/knob, it's got a small cap on top of it and a slot where a screwdriver fits - I guess it's so that you can only turn it in one direction and that you have to do something with a screwdriver to allow you to turn the tap/knob back the other way.

I've never seen one like this before in this particular place - I think my boiler was installed by the Late Lord Sutch. My apologies, as before, if this is the most foolish question.

 

[clf-gas]

However, I'm trying to increase the water pressure on the boiler in my flat for the first time since I moved in.

Thanks for the response but it's not the filling of the system that is the main concern.

Got me confused as well

Can you post a picture

 

[kevindgas]

sounds like the old vokera filling loop which consisted of two tap heads with a pipe between
try turning it on and see if A. you get wet or B. the pressure on the heating rises.

 

[Rub]

I'll have a bash later on and see what happens otherwise try and take a photo of the strange tap with a screwdriver/cap thing. Thanks for the help so far.