Air trapped behind check valve?

Question

I recently installed a thermostatic mixing valve on the hot water feed to my shower pump which has a max water temp. (One of these https://www.commercialwashroomsltd.co.uk/assets/docs/products/TMV3_Spec_sheet.pdf ) This has an integral check valve.

However I seem to have an air lock in the system. I can clearly hear the water trickling down the mixed outlet. Is it possible that this is cause by air trapped behind the check valves? Is this even physically possible? I have tried draining and refilling the system to try and remove the air.

Any help is greatly appreciated. Thanks

About the system: Gravity fed. Dedicated supply to the mixer valve from both the hot water cyclinder and cold water tank which feeds into the shower pump that feeds just one shower.

Answer 1

Solution was to remove the cold water feed downstream of the check valve and remove the air from the mixed pipe using the hot water feed. I then reattached the cold feed. There is probably still a small amount of air in there but it doesn't noticeable impact the flow.