Turn the power switch on the pump control to the "Off" position.
Close the valves for the steam inlet/high temperature pipes by turning each valve knob clockwise.
Place a bucket below the pressure relief valve on the side of the generator. Put on work gloves then open the valve slowly to let the water drain out.
Wait until the tank is cool to the touch. Close the three remaining valves in this order: the hot water outlet, the cold water inlet then the condensate return line. Each valve knob twists clockwise, and all are labeled on the generator unit.
Place the bucket under the drain valve. Open the drain valve then slowly open the pressure relief valve as far as the knob will turn. This prevents an air vacuum from building in the tank.
Clean the tank exterior and the heat exchanger with a solution of liquid soap and water then wipe the unit down with old towels. Allow the tank to air-dry.
Start the steam generator by closing the drain and pressure valves then opening the water valves in the reverse order that they were shut down. Switch on the power once the valves are open.