hot water secondary return check valves

[davidallanmcdonald]

I,m about to change from plastic fitting to copper and want to add a check valve into my secondary hot water return line what prevents the hot water sucking the water out of the secondary return line the plumber that fitted it is no longer here so I cant ask why a check valve wasnt installed when it was originally fitted

 

[Scott_D]

Is the secondary return pipework in plastic?
Check valve after the pump.
Any pictures of your setup?

 

[davidallanmcdonald]

No from the cupboard onwards is all copper and the rest of the plastic is being replaced very soon I plan to put a nrv in the line after secondary pump

 

[Chalked]

Use a swing check valve, or a very lightly sprung non return.
swing are best, as they won’t restrict the pump. But they will need fitting the correct orientation so the check valve falls to shut.