Disconnect the power on your heating and cooling system. Either turn off the emergency switch located on the furnace or switch the fuse to "Off" on your home's electrical box.
Unplug the UV system and allow it to cool down for at least 15 minutes.
Turn the lamp handle counterclockwise and pull the handle to remove the bulb.
Hold the lamp handle in one hand. Spray a soft cloth with glass cleaner until damp. Wipe the lamp glass with the soft cloth. If you touch any part of the glass with your bare hand, wipe it off to prevent leaving oils on the glass.
Wipe away dust between the lamp light indicator and the black bulb base.
Dry the bulb with a new dry, clean cloth.
Set the lamp light indicator at the eleven o'clock position. Push the bulb back into the base while rotating it counterclockwise until the handle fully sits in the base.
Turn the lamp handle clockwise until it fully snaps into place. Align the lamp light indicator with the unit cover's raised button.
Turn the power to your UV system back on.
Turn your heating and cooling system back on.