The orifice gasket in a furnace serves as a valuable seal between the blower's motor assembly and the main body of the furnace. Without the gasket, the blower could leak additional air and cause the unit to become far less efficient. If you know that your orifice plate gasket is worn or missing, you can conduct the replacement yourself with a small amount of work.
Note that working with HVAC equipment always carries some risk even when the electricity is turned off. There are sharp edges and heavy parts that need to be moved out of the way. If you at any point feel unqualified, call in a furnace repair person to complete the job.
What You Need:
- Stiff brush
- Bucket with dish soap and water
- New orifice plate gasket
Step 1: Remove the Existing Orifice Plate Gasket
Turn off the electricity to the furnace at the circuit breaker. Look at the access panels on the back of your furnace and determine how the panels are held in place. The fasteners are usually either screws or knobs that you simply twist to release the door. Remove the fasteners for the upper panel door using either a screwdriver or your hands. Set the door aside.
Locate the exhaust vent, then use your screwdriver to remove the vent's mounting screws. Pull the vent up to detach the vent from its base. Set the end of the vent down onto the top of the furnace to hold it in place for now.
Disconnect the draft inducer wire harness by finding the plugged connector in the center and unplugging the sections from one another. Detach the pressure tube. Use a wrench to unfasten the mounting screws that hold the motor assembly in place. Pull the motor assembly out of the furnace.
Peel off the orifice plate gasket from the motor assembly. Dip a stiff brush in a mixture of dish soap and water. Use the brush to clean off as much leftover gasket residue as you can. Pat the scrubbed area with dry with paper towels.
Step 2: Install the New Orifice Plate Gasket
Line up the new orifice plate gasket on the motor housing. Hold the gasket in place with your hand as you insert the motor assembly back into its place in the furnace. Secure the assembly with its mounting screws. Attach the pressure tube to the motor assembly.
Connect the plugged ends of the wire harness. Lift up the exhaust vent from its position on the furnace top, then drop it down into its appropriate place. Secure the screws to hold the exhaust vent in place.
Place the upper access panel door back on the furnace and secure its fasteners. Turn the electricity back on to operate your furnace. Contact a company like Butler Heating & Air for more information or assistance with this task.