Why do I have two overflow lines plumbed from my hot water heater. I know what the one is for the pressure relief valve, but I have another one plumber directly after the shutoff valve on the cold water inlet. This one drains all the time outside and I am not sure why. It is not necessarily hot water coming from it as it is backing up in the cold water inlet. I have not been able to find any information on why the second overflow line would be plumbed and why it runs continuously.

Thank you for your feedback

  • 1
    What kind of hot water heater is this? is the second line "running all of the time" a condensate drain? Can you share the make and model of heater and the fuel source? – noybman Jan 6 '19 at 20:59
  • Does your water heater have a thermal expansion tank? This would be installed on the cold water inlet after the shutoff valve. – BillDOe Jan 6 '19 at 21:11
  • it is an electric water heater. Yes, the overflow line that is plumbed directly after the shut off valve runs water outside all the time. It is plumbed as a small water line, not like the overflow PVC line for the pressure relief valve. It actually comes out of the side of the house with the overflow PVC line. – Robert Jan 6 '19 at 21:11
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    Can you take some pictures? – HazardousGlitch Jan 6 '19 at 21:49
  • 1
    ... might it be a malfunctioning backflow preventer? – Daniel Griscom Jan 7 '19 at 0:06

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