A valve assembly for a water circulation system includes a valve body defining a bypass passage between a hot water side and a cold water side of the valve body. The bypass passage has a valve seat therein. A bypass valve is received within the bypass passage. The bypass valve restricts the flow of water through the bypass passage based on a temperature of the water in the bypass passage. The bypass valve is variably positionable with respect to the valve seat to control a bypass shut-off temperature of the water.