A check valve on a dedicated hot water return line helps keep water moving in the intended direction. If it sticks open, water can sometimes take an unintended path when another fixture runs. If it sticks closed, circulation can drop even while the pump is on.
Record symptoms while the pump runs
Note which fixtures are slow to warm and whether the issue changes when the pump is scheduled off. Tell the technician if you first noticed the problem after work on the heater or return line.
Confirm the direction before replacing parts
A technician can trace the return line and check the valve orientation, pump operation, and temperatures. Ask which finding points to the valve before replacing it.
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