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MikeJJ's Achievements

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  1. My neighbor and I have both experienced this expansion tank phenomenon after getting new water heaters with expansion tanks, when previously we didn't have them. Apparently(?) they are not needed in an open system the lets the hot water expansion push back out to the street. When an expansion tank is on such a system, and if it is pressurized nearly equal to the incoming pressure, fluctuations in incoming street pressure can fill and empty the tank continuously. Since the meters in our case won't reverse, our water bill included the frequent fills. To solve this, my neighbor installed a check valve. I simply added extra air pressure to the tank (50psi vs the 42psi incoming). In both cases, the leak detector meter stopped spinning. But what I don't understand, is wouldn't the same thing happen without an expansion tank in an open system? Wouldn't the fluctuations in the mainline pressure cause water to flow from the hot water tank back to the street when pressure drops and then back into the hot water tank when pressure increases again?
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