Most installation jobs involve removing the old water heater before installing the new one. Removing an old electric water heater begins by turning off the power to the water heater at the breaker box and testing the wires to ensure that the power is off.
Locking the panel is a good idea; this will ensure that no one accidentally turns the power back on while doing the work. Now locate the water heater’s electric panel and remove the screws that hold it on. Disconnect the wires and mark them so they will be hooked up correctly on the new water heater.
After disconnecting the wiring, it is time to disconnect the water. Begin by shutting off the water supply to the water heater, either by shutting off the cold-water valve generally located on the right side on the top of the heater or by shutting off the water supply to the entire house. If there is no cold water valve on the old water heater, installing one on the new water heater will be a good idea.
After shutting off the water supply, it is time to drain the tank. Open all the hot water spigots in the house to help drain the tank. If there is a floor drain, open the drain valve at the bottom of the tank allowing the tank to drain. If there is no floor drain, connect a garden hose to the drain valve and run the hose outside to an area where the hot water can be released safely while draining the tank. Completely drain the water from the tank. Another way to empty the water heater is to drain the water into a bucket and dump it.
Once the tank is drained, it is time to disconnect the cold-water inlet and the hot water outlet pipes. If the pipes are hard-plumbed to the water heater, it will be necessary to use a hacksaw and cut the pipes about six inches above the water heater. However, if the pipes are attached with water heater connector hoses, simply unscrew them. Now the water heater is ready for removal.
Tips that can aid in removing the water heater are to install two nipples to the top of the water heater to use as handles when moving the water heater and to wear gloves because the legs of the water heater can be sharp. Another important tip is to have some one help remove the water heater, as they can be heavy. After removing the water heater, inspect the piping and valves and decide if they can be reused or will need to be replaced. If it has been determined that the piping or valves need to be replaced, do that now.
Now install the new water heater by positioning the new unit so that the pipes line up correctly, cold on cold and the hot on hot. The cold-water piping is generally the one on the right side with the valve on it. Next, install a new ¾” relief valve, with the temperature sensor inserted into the hot water heater, using Teflon tape or pipe dope. Installing a new blow off tube on the female threads located on the relief valve, extending to within 6” of the floor should be the next step.
At this point, connect the piping to the water heater unit using a tape measure to ensure the correct lengths. Only use hard piping and if the pipe in the house is galvanized then the pipe to be used should be galvanized, same with copper, if the piping in the house is copper, only use copper piping on the water heater. Do not mix unlike metals. Use Teflon tape or pipe dope on galvanized piping connections and solder copper piping connections.
After the piping is all connected, it is time to fill the water tank. Make sure the hot water spigots are still open so trapped air can escape. Turn the cold water supply back on to the water heater and allow the tank to fill. Once water flows from each spigot, allow it to run for one minute before tuning off the spigots. Check all the connections for leaks.
If there are no leaks in the system, reconnect the wiring to the heater as directed by the manufacturer’s instructions. Turn the breaker back on and there should be hot water in a couple of hours.