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How to Troubleshoot a Power Vent Gas Furnace

A power vent furnace uses a blower called a power venter to carry the gases produced by combustion outside. The power venter unit is activated by the thermostat. The power venter activation creates a negative pressure, which activates the burner. When the thermostat senses that enough heat has been provided, it shuts down the burner, while the power venter continues to move gases outside. A timer or a temperature control typically determines when the power venter can shut off. Problems can occur with a power vent furnace, but troubleshooting may resolve these without a call to a technician.

Things You'll Need

  • Wire brush
  • Compressed air
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Instructions

  1. Delayed Ignition or No Ignition

    • 1

      Ensure that the gas is turned on and that there are no drafts near the pilot assembly, such as an open window or a fan.

    • 2

      Adjust the air shutter control, located on the burner assembly, by turning it clockwise to close it slightly. A delayed flame indicates you may have too much air flow to the burner.

    • 3

      Close the shutter until a yellow tip appears in the flames and then open again, just beyond the position that the yellow tip disappears.

    • 4

      Turn off the main gas supply and the electrical power to the furnace if adjusting air flow doesn’t resolve the problem. The burner may be clogged and requires cleaning.

    • 5

      Remove the bottom panel of your furnace and move the burner toward the manifold to compress the spring. Slide the other end of the burner down while the spring is compressed and pull away from the manifold.

    • 6

      Clean the surfaces of the heat exchanger with a wire brush and blow away any dust or debris with compressed air. Inspect all parts of the burner to ensure they are not blocked.

    • 7

      Replace the burner by sliding it down to compress the spring and push it down into the manifold. If you cannot remove the burner from your furnace, you can blow compressed air into the ports on the burner to try to remove debris.

    • 8

      Turn the gas supply and electricity back on and start the furnace again. If you still experience problems with ignition, contact a technician to inspect the unit. You may have a defective thermostat or limit switch.

    Power Vent Not Running

    • 9

      Ensure the furnace is receiving power from the breaker panel or fuse box. Replace or reset blown fuses or tripped breakers.

    • 10

      Inspect all wiring to the power vent system. Tighten all connections. If wires are damaged or missing, contact an electrician for repair.

    • 11

      Check the terminals on the fan relay with a multimeter. If there is no power, the relay or the fan motor may be defective and should be replaced.

    Power Venter Is Noisy When Operating

    • 12

      Tighten the venter wheel located on the side of the power venter assembly. A loose wheel can cause noisy operation. If the wheel is too tight, however, it may rub on the housing, which can also cause noise.

    • 13

      Remove dust or debris from the power venter wheel using compressed air. If dirt builds up around the wheel, this can cause it to operate with some noise.

    • 14

      Oil the bearings on the power venter motor. Dry bearings may cause noisy operation. Refer to the label on your power venter motor for the type of oil to use.