thermostatic shower prob

[steviebabe]

fitted one a couple of months ago ,its playing up sometimes no water will come through .i have a pump thats working fine ,the prob is i have to disconnect the cold feed to the shower and that starts the pump running and its fine for a bit then when i turn the shower on later it wont work unless i do the same thing again ,anyone help could it be the shower unit cos it worked fine for about 3 months.sorry i have the pump fed from the cylinder and its directly below

 

[steve32]

need more info
make and model of pump and shower
where is pump located

 

[steviebabe]

its a easiboost showerforce and its situated next to the h water cylinder

 

[steve32]

still not enough info
make of shower, model thermo or manual
built in pump or separate pump and location to shower