Help to repressurise boiler

[M. L.]

Saunier Duval F28e the pressure has dropped and its not working just 0.4.

The British gas man told me how to repressure it and I think said to turn the yellow plastic tap but its stiff I dont know which way and fear forcing it. Also this is not as the manual suggests which has two points but the plumbing to mine doesnt look like the manual.

There is a slow leak coming from the point marked by the arrow where there is a screw head

Help!

 

[M. L.]

By the way it was months ago when BG serviced it, which is why I dont recall exactly what was said

 

[Madrab]

Looking at that picture it's not the 28e, its a 28e SB. In other words you'll have a hot water cylinder and it's a system boiler you have and not a combi, they are filled by different methods. If you are talking about the yellow tap in the middle then no, that's the gas valve.

You'll probably have a filling loop attached to the pipework somewhere, you need to look for a silver braided hose connected between 2 of the pipes with 1 or 2 black taps on it.
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[ianmcd]

And you need to get that leak sorted or the pressure will continue to drop