Help! Water pump pressurizing when using hot water tank.

Thanks for the diagram Old-Biscuit - Additional notes - have flex pipe on inlet and outlet. Have tried 'trial and error' on adjustments with pressure settings on pump - little change - shortening of 3-5 sec pressurization to 2-3 secs maybe. Water hammering is on 4-5 ft hard pex line after looped flex outlet line reaches hard pex distribution lines. So frustrating! Maybe I'll try staring at it some more.