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How to Fix a General Aire Humidifier Model 800

Jon Stefansson

The GeneralAire Model 800 humidifier is designed to sit inside duct work and add moisture to the air. Some respiratory problems are exacerbated by dry air. Fixing your malfunctioning Model 800 from home is a good way to save money on the cost of a technician.

In some cases there is a simple fix that can be easily be implemented from home with little expertise.

  1. Make sure the water supply to the humidifier is open. Follow the tubing from the unit to the saddle valve connected to your home's plumbing and make sure the valve is fully open. Remove the inspection plate on the front of the humidifier and look for water dripping into the unit or a pool of roughly an inch. Move the actuator plate -- accessible through the viewing window -- toward the pan to increase the flow.

  2. Have the water pressure in your home inspected. The Model 800 is designed to operate with a water pressure of between 20 and 150 pounds per square inch. Low pressure is often most noticeable when water runs slowly from the faucets. If the pressure is too low, a plumber can install a device to rectify the problem. Alternatively, if your home has a pressure adjustment valve near the meter, you can increase the pressure yourself.

  3. Turn off the water supply to the Model 800 and disconnect the pipe. Remove the screws holding the humidifier into the ducting and slide the unit out to reveal the five evaporator plates. GeneralAire recommends replacing these plates and cleaning the pan at the end of every season of use. To remove the plates, simply pull them from their sockets. Slide in fresh GeneralAire 880 plates and clean the pan with a scouring pad. Rinse the pan thoroughly and slide the unit back into position. Failing to replace the plates or clean the pan reduces the unit's efficiency.

  4. Remove the four screws holding the water valve -- the part that the water line connects to -- on the front of the appliance, and pull the body from the neoprene valve. Pry the screen disc out of the orifice in the valve with an unfolded paper clip and clean the disc in a sink of soapy water. Wipe away any dirt in the orifice and reassemble the connection, being careful not to overtighten the screws of the valve body.

  5. Hook the water back up, open the valve and watch the pan fill from behind the inspection plate. When the water is roughly 1/4 inch above the holes in the pan baffle, turn the adjusting screw a little at a time until the water turns off. The position of this screw sets the level of the water in the unit. You might find the unit fails to work as expected if the level is set too low.