Try this, start from cold, switch on heating, and feel the pipe on top of pump, does that get hot first than return pipe going back to boiler?
If the pump pipe get hot first, that is correct and fine. It does not matter which flow or return to lock shield or TRV.
It need to be balanced to get even heat across.
Daniel
If the pump pipe get hot first, that is correct and fine. It does not matter which flow or return to lock shield or TRV.
It need to be balanced to get even heat across.
Daniel