bath shower mixer

[robbymearns64]

can anyone help here, i fitted a bath shower mixer (thermostatic) and the shower part seems fine but when i turn the temp down the flow of water comes to a trickle also when i try fill a bath the cold water tricles out and makes a horrible noise, any ideas what could be wrong and any fixes ???
thanks for any help
robert

 

[swidders]

few more details - combi? cylinder? mains pressure in bathroom for both hot and cold, what's happening at other taps, what sort of noise?

 

[Dan Robinson]

hot and cold feeds the right way round?

 

[robbymearns64]

few more details - combi? cylinder? mains pressure in bathroom for both hot and cold, what's happening at other taps, what sort of noise?

it's a cylinder which is in a cupboard right behind the bath and at same level as bath, storage feeding both taps, suplies are fitted correctly, other taps seem fine, the noise is like a loud humming or vibrating sound, hopes this helps and thanks for your input.