With the water supply still on, turn a faucet on hot and let it run until the water is cool. Shut off the cold-water supply line and connect a garden hose to the drain valve on the bottom of the water heater.
When the tank is empty, remove the discharge pipe from the temperature and pressure (T&P) relief valve. Disconnect the water supply lines. If you must cut them, leave them as long as possible. Have someone help you remove the old tank with a hand truck.
Installing the New Water Heater
The following steps will explain how to install an electric water heater.
If your water heater didn't come with a new T&P relief valve installed, simply twist in the new valve now. It may be in the box or you may need to buy your own. Don't reuse the old valve. The T&P valve automatically opens if the temperature or pressure becomes too high for the tank. The T&P valve most of the time came directly installed.
Position the discharge pipe from the T&P relief valve toward the floor or drain. If there's no drain underneath the pipe, put a bucket underneath to catch water dripping from the discharge pipe. Cut the pipe so it's no more than 6 inches above the bucket.
Use a flexible hose kit for water hookup. In Illinois is prohibited to use flexible hose. Use type "L" or "M" copper pipe.Apply plumbers tape to the threads of the heat trap nipples. Then attach the hoses.
Some areas require seismic straps to prevent earthquake damage. These straps brace the water tank against the wall to keep the unit from toppling over. If you’re not in an earthquake zone, skip ahead to the next step.
Seismic straps should be installed approximately 6 inches from the top of the water heater and 18 inches from the bottom. Locate the wall studs closest to the strap measurement and drill pilot holes.
Secure one end of the strap to the stud with a socket and ratchet. If blocks cover the studs, use a masonry bit to create a pilot hole. Wrap the strap around the water heater and adjust the size, securing the adjustable bracket on the opposite side. Pull the strap tight and repeat the process on the lower strap.
Remove the aerator from the nearest faucet and open the hot side. Slowly turn on the water supply and check connections around the water heater for leaks. If you're leak free, fill the tank. If you have leaks, shut off the water supply and gently tighten the connections. Repeat until the connections are secure.
If a faucet stops running after installation, remove the aerator from the faucet in question and let the water run for a few minutes to clear loose sediment. Rinse and replace the aerator.
Even with the temperature gauge set to 120 degrees, scalds are still a concern. Children, older people and those with sensitive skin are especially at risk. Consider installing thermostatic mixing valves to prevent injury.
Installed at the point-of-use faucet, fixture or appliance, a thermostatic mixing valve controls both the volume and temperature of water by attaching to both the hot- and cold-water supply. The settings may be adjusted inside the valve itself to provide optimum comfort.
Solder the connections to the valve before attaching to the plumbing. Connect the valve to the hot- and cold-water supply and the outlet pipe. If additional soldering is needed, maintain a safe distance from the valve because excessive heat may cause damage.