The check valve keeps the proper flow of hot water in a single direction, that is to keep hot water from backflowing. As the water heats up, it expands, and hot water is pushed back into the cold-water lines or water heater. Depending on your plumbing configuration it may or may not seem to make a difference. It does have a purpose in the system.
Every day's a learning experience, though sometimes not what we expected.
2012 Jay Flight 19RD
2016 Ford F150 XLT 2X4 SC 3.5L Eco Max Tow
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2 new fluffy Corgis, Bayley and Stanley