Consider a small circ pump. Grundfos Series UP is designed just for this purpose, 3 GPM, 5¼’ head, built in 24 hr adjustable timer, full union with isolation and check valves.
Don’t use an oversized circ pump for hot water in copper tube! The cu will pit corrode at hot water flow velocities over about 3FPS. BTDT! Google it.
FYI, 1 GPM in ¾” type L Cu tube = 2 FPS flow velocity.
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