How to Replace Furnace Condensate Pumps

A condensate pump collects and removes the condensate a furnace's evaporator coil creates. The furnace's drain line dumps condensate into the condensate pump's holding pan. Once the condensate in the holding pan reaches a set level, the pump's float switch activates the pump motor. The pump motor pulls the condensate out of the holding pan and forces it into a discharge drain line. The discharge drain line either dumps the condensate into a gravity-fed drainpipe or directs the condensate to the exterior of the building. A replacement furnace condensate pump reuses the original pump's drain lines and electrical connections.

Wire cutters
Slotted screwdriver
Wire strippers

Instructions

- 1
  Turn off the circuit breaker labeled "Furnace" or "Air Handler." The condensate pump's low-voltage safety switch taps into the furnace's low-voltage transformer circuit.
- 2
  Pull the old condensate pump's electrical plug from its wall receptacle. A condensate pump motor plugs into a standard 120-volt wall receptacle.
- 3
  Cut the condensate pump's safety switch wire set, the 16- or 18-gauge two-strand wire set that runs from the condensate pump to the furnace, about 6 inches from the condensate pump with wire cutters. This wire set connects the condensate pump's safety switch to the furnace transformer.
- 4
  Loosen the hose clamp holding the condensate pump's 3/8-inch discharge tube to the pump's discharge fitting, using a slotted screwdriver to turn the hose clamp counterclockwise. Slide the hose clamp up the discharge tube and away from the condensate pump. The hose clamp locks the discharge tube against the discharge fitting's barbs.
- 5
  Pull the discharge tube off the condensate pump's discharge fitting, using a hand to slide the tube over the fitting's barbs.
- 6
  Lift the furnace drainpipe out of the condensate pump's intake port. The furnace's 3/4- to 1-inch-wide drainpipe slides into a hole located in the top of the condensate pump's holding pan.
- 7
  Remove the old furnace condensate pump. Set the new condensate pump in its place.
- 8
  Insert the end of the furnace's 3/4- to 1-inch-wide drainpipe into the condensate pump's intake port. The furnace drainpipe slips into the round hole located on top of the condensate pump's holding tank.
- 9
  Force the end of the discharge tube onto the new condensate pump's barbed discharge fitting. The end of the discharge tube must completely cover all of the discharge fitting's barbs.
- 10
  Slide the hose clamp down the discharge tube and position the hose clamp about 1/8 of an inch from the end of the discharge tube. Tighten the hose clamp, using the slotted screwdriver to turn the hose clamp clockwise. The hose clamp will squeeze the discharge tube against the discharge fitting.
- 11
  Remove 3/8 of an inch of the insulation from the ends of the two furnace transformer 16- or 18-gauge wire strands, using wire strippers.
- 12
  Twist one of the new condensate pump's interchangeable safety switch wire strands around one of the furnace transformer's wire strands. Cover the wire ends with a wire nut. Repeat this procedure with the second safety switch wire and the second transformer wire.
- 13
  Push the new condensate pump's electrical plug into the 120-volt wall receptacle. Flip the furnace's circuit breaker to the "On" position.

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