My old hot water tank met its maker about two or three weeks ago, and since then I have installed a new Kenmore 50 gallon gas water heater to replace it.

The new water heater seems to work fine, I was able to hook up the hot and cold lines with the new fangled compression fittings and special 3/4" to 1/2" couplers (I have a 60 year old house, all the water lines are 1/2"OD copper while the water heater came with 3/4"). Because of the hack job on the copper tubing that was there I just got that flexibile ribbed tubing to go from the existing water lines to the water heater.

Little bit of sweating at the fittings, no leaks though. Sprayed leak detector on the gas line, no bubbles. Everything seems good.

Ever since I got the thing the relief valve has been steadily dripping water onto my basement floor. I have an expansion tank going to it, although it is about 3 or 4 feet away from the water heater for overhead space reasons. I typically see these installed much closer to the unit itself, never 3 or 4 feet away if this makes a difference at all in how it performs. It is not leaking there is no rust or any other signs that the bladder inside it is leaking. When installing these you want to make sure they are on the cold line correct?

So I thought perhaps I have the temperature too hot, it was at B, I have since turned it down to A with no noticeable difference.

Water pressure coming to the house has always been extraordinarily high, but I tightened the pressure regulator enough that it should be well under 80 psi.

It is leaking probably over half a liter of water each day. Something wrong with what I did, setup, existing issues with the plumbing? Faulty relief valve? Is it okay to just install a hose from the relief valve and just have that water drain to the A/C water pump and ignore it?

  • 1
    Have you measured the pressure?
    – BMitch
    Commented May 4, 2012 at 11:55
  • Is the pressure on the new tpr less than the old one? What type of pressure reg are you using?
    – UNECS
    Commented May 4, 2012 at 11:57
  • 1
    Buy a psi gauge from the local hardware store (couple bucks) and screw it on a garden faucet. Leave the garden faucet open but all other faucets closed while the water heater is in a heating cycle. Measure at the beginning and end of the heating cycle.
    – BMitch
    Commented May 4, 2012 at 12:00
  • 1
    Temprature and pressure relief valve. Should have a tag with the pressure and temp rating on it.
    – UNECS
    Commented May 4, 2012 at 12:05
  • 1
    If it's steadily dripping, it could simply be that there is some debris stuck on the seal of the TPR valve preventing it from sealing shut. Have you tried fully opening the TPR valve and letting it flow for a few seconds? I would do this a few times and see if it seals after that.
    – pdd
    Commented Jun 4, 2012 at 20:16

2 Answers 2


A few things to check;

  • Did you place the expansion tank on the cold water side?

  • Did you pressurize the expansion tank to the same pressure that the water line is at after the regulator?

  • Is the expansion tank size rated for the size of your hot water heater?

  • 1) It is on the cold water side. 2) How do you repressurize the expansion tank? The pressure changed shortly after buying the house and realizing that the pressure was obscenely high and the pressure regulator was not being used 3) The old heater is the same size as the new heater. Commented May 4, 2012 at 12:31
  • 1
    The expansion tank pressure should be the same pressure as your water pressure. Shut down your main water valve, and open some faucets. That will reduce the pressure in the system. Measure the air pressure in the expansion tank, a standard tire gauge can be used for this. Add air to equal the same value of water pressure you measured at the water regulator. Turn the water main back on, Your done:)
    – SteveR
    Commented May 4, 2012 at 16:52
  • Thank you, you gave me something fun to do over the weekend! Commented May 4, 2012 at 18:14

80 psi is way too high for house water pressure. toilet valves and other devices will start to fail. Recommended pressure is 55 psi

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