Installing an Electric Tankless Water Heater

Water heaters are the invisible workhorses of the home, but a standard tank unit consumes massive amounts of space and energy by keeping gallons of water hot 24/7. Moving to a tankless system means heating water only when you turn the faucet, which drastically reduces your standby energy loss. Doing this well requires a clean installation that respects the high power demands of the unit and the integrity of your plumbing connections. Efficiency in this project is all about the planning stage. Before you pull the old tank, verify that your home's electrical service can handle the amperage draw of the new unit. Most electric tankless models require a dedicated heavy-duty circuit that standard outlets simply cannot support. Once the power is confirmed, the physical mounting and plumbing are straightforward tasks that yield a more responsive, space-saving hot water delivery system.

  1. Kill Power and Water First. Turn off the main water supply to the house or the specific supply line to the water heater. Switch off the dedicated double-pole circuit breakers at the main electrical panel to ensure the area is dead.
  2. Secure to the Wall. Hold the unit against the wall in your chosen location, ensuring it is level and clear of other pipes. Mark the pilot holes and secure the mounting bracket to the wall using heavy-duty anchors or direct studs.
  3. Connect Inlet and Outlet. Attach isolation valves to the cold inlet and hot outlet of the heater. Connect your copper or PEX supply lines to these valves, ensuring you use the correct transition fittings for your pipe material.
  4. Wire for Heavy Load. Feed your heavy-gauge electrical cable through the unit's knockouts using a proper strain relief connector. Connect the wires according to the manufacturer's terminal block diagram, ensuring a tight connection for each hot leg and the ground wire.
  5. Bleed Air from Lines. Open the isolation valves and turn on the nearest hot water faucet to flush all air out of the lines. Allow the water to run steadily for two minutes before turning on the circuit breakers.
  6. Test Temperature and Settings. Once the power is restored, set the desired output temperature on the unit's control panel. Run a test at the furthest faucet to ensure the temperature reaches the target within a reasonable timeframe.