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Before leaving on vacation I set the thermostat on my hot water tank to VACATION setting. Having been gone for 1 month, upon my return I set the tank back to my normal setting...Medium hot. I just noticed that my pressure relief valve discharged about a pint of water. HWT is 40 Gallon Gas. I have drained another quart of hot water from the pressure relief valve. No discharge so far. Should I be concerned if no further discharge occurs?

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Two thoughts that come to mind are mineral buildup on the expansion valve that you cleared away, and a dramatic pressure difference from heating cold water from room temperature without opening any faucets and a check valve. You'd want to attach a pressure gauge to the line and monitor it to see if there's any cause for concern. –  BMitch May 4 '14 at 23:42

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