You just had city water installed, and now your hot water tank is leaking out of the relief valve! The following information will provide steps to help you solve the problem.
The first rule to remember is that as water is heated, it will expand. Before getting city water you likely had a pump and cold water expansion tank in your house. As the water heater did its job, the expanded water would push back the line into the expansion tank.
It is common after installing city water to have no expansion tank and a check valve installed in the new waterline. When the hot water tank heats water, the expanded water has nowhere to go, thus building excess pressure and blowing it out of your water heater relief valve.
The solution is to install a small expansion tank on the cold water line above your water heater.
We carry an expansion tank for hot water. It is our item # 41-300 A tee fitting is required for the cold water line to go to a ¾ “ female pipe thread to accept the tank threads. You will need enough room for the tank to hang. It is advisable to have some support for the water line as well, to avoid putting undo strain on it, causing it to break and create another problem.
You may also want to replace the relief valve, our item 41-274, on your water heater as it may still drip after being opened by high pressure a few times.
Good article on expansion tanks from a building code point of view: http://www.wvdhhr.org/phs/water/thermal_expansion2.pdf
Here is a link to Zurn’s installation document. for the XT expansion tank.