Step 8 · Reassemble and Restore Power

With the new thermostat installed and wired, set its temperature dial to the recommended 120°F (49°C). Carefully tuck the insulation back into the openings, making sure it doesn't pinch any wires or obstruct the thermostat. Place the metal access panels back over the openings and secure them with their screws using your screwdriver or nut driver. Finally, return to the electrical panel and switch the water heater's circuit breaker back to the 'ON' position.