No water pressure for the shower

[Space monkey]

Hello everyone this is my first post on this forum so please be kind

anyway at my problem is when I turn on the shower the water doesn't come out of the shower with as much water pressure as it should, what I've been told already is that there may be air trapped in the pipes but I'm unsure on how to get rid of the trapped air from the pipes, the system that is used is a triton system (if that helps) there are two pipes coming from the small box that controls the tank, with two release valves with are turned with a screw driver I have turned them as much as I dare to go but nothing seemed to happen, so I decided to tighten them back up, but after a while they seemed to not get any tighter or start to give any resistance.
So should I keep turning the these valves and keep testing it by turning on the shower again or is there another way to realise the trapped air in the pipes?

 

[Radioman]

"two pipes coming from the small box that controls the tank, with two release valves "

Sorry makes no sense. What model Triton? What hot water system do you have?

 

[THEJoeb]

google 15mm isolation valves image, they're most likely the valves you are talking about. if it is them,
then you don't keep turning them. when the two nuts are at 12 and 6 o'clock, the screw line should look like 6:00 to be open fully, when the screw line looks like is at 9 and 3 then it should be closed.

I know you said you have a tank so I assume you do not have a combi. with you not being a plumber best thing you can do is open every hot tap in the house at the same time start downstairs to upstairs, then close the taps starting with the one you opened downstairs 1st, and so on. there are other things you can do but would not advise to DIYers.

hope it helps