How to Replace an Existing Electric Hot Water Tank

An electric resistor element within a hot water heater warms unheated water as it flows into the tank. When a faucet is turned on, the hot water exits the tank and more unheated water enters. This cycle continues as hot water is used. Over time, because of constant immersion in water, the interior of the heater wears out and corrodes--when this happens, it's time to replace the old heater. Doing this job yourself isn't easy, but is fairly straightforward.

• 1

  Turn off the water supply to the heater. Empty the heater by attaching a hose to the drain at the bottom of the heater. Open the drain and allow the water to flow downhill, away from the heater.

• 2

  Turn the breaker to the electric water heater OFF at the breaker box and test the terminal on top of the heater with a circuit tester. Remove the terminal housing plate from the top of the heater with a Phillips-head screwdriver. Make a note of where the wires are connected, then uncouple the wiring from the heater. Attach wire nuts onto the bare wires (in case the circuit breaker is accidentally turned on).

• 3

  Cut the two, 3/4-inch copper pipes between 2 and 4 inches away from where they enter the top of the heater, using a pipe cutter. Slide the old heater away from the cut pipes.

• 4

  Place the new heater in the same way as the old. Install 3/4-inch male screw connectors into the top of the new heater and tighten them into the screw holes with an adjustable wrench. Measure the distance between where the supply pipes were cut and where the new pipes will sit in the new connectors, using a tape measure Cut and clean copper pipe to this measurement. Place the cut pipes into the new connectors.

• 5

  Slide copper connecting sleeves over the supply pipes and slide them high up the pipe. Position the heater under the supply pipes and slide the sleeves down, over the new pipes to connect them. If the pipes fit correctly, remove all the connections and clean the surfaces to be soldered with emery paper.

• 6

  Brush plumber's flux onto all the surfaces to be soldered. Connect the new pipe and male connectors first and sweat the connections with lead-free solder. After they have cooled, screw the male connectors into the top of the heater and tighten them with an adjustable wrench.

• 7

  Slide the copper sleeves onto the supply pipes and slide them high up. Position the heater under the supply pipes and slide the sleeves down over the new pipe. Ensure an equal part of each end of the pipe is contained within the sleeve. Sweat these connections together with lead-free solder.

• 8

  Connect the electrical supply to the terminals in the same way as it was removed. Replace the terminal housing cover.

• 9

  Turn the water back on and allow the tank to fill completely before turning on the power. When the tank is full, turn the breaker on and wait for the water to heat.