Before beginning the electric hot water boiler installation, the installer should gather basic plumbing tools, pipe joint compound and a circuit tester. The installer needs to turn off the power to the old water heater and check all of the wires and circuits with the circuit tester.
Once all off the circuits are verified to be off, a hot-water faucet in the home should be opened and run until the water is cool. At this point, the cold-water supply to the water heater should be turned off, and a garden hose needs to be attached to the drain valve. The other end needs to go outside or into a drain. Then, the valve should be opened. When empty, the old water heater should be removed.
If the water heater requires a thermal expansion tank, this should be installed based on the manufacturer's instructions. The pipe from the tank should end near a floor drain about 6 inches from the floor. The hot and cold water lines should be installed and soldered to the new tank. The cold water line should be opened and the new tank filled. A hot-water faucet should be opened and allowed to run for about three minutes.
At this point, the electrical power can be turned on, and the tank can be checked for leaks, proper temperature and water pressure.