Multiple zones and non return valves

[coopersim]

I’m getting chattering from non return valves on my heating system when the zone ports or partially open (vaillant weather compensation controlled)

Are non return valves essential in this instance or can I remove them?

for clarity each zone is piped with flow and return to a bespoke 28mm manifold with four port valves and four returns with non return valves

 

[cross thread]

Sure it will work without the valves as they all come back to the manifold

 

[muggles]

Presumably the installer thought they were necessary, but swing type check valves would have been better