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Sub-Zero UC-15I Gravity Drain or Pump Selection Considerations


  • Why purchase the UC-15IP over the UC-15I?
  • What should be considered when selecting a UC-15I(P)?
  • How to pick between a gravity drain and pump Undercounter Ice Maker
  • Does the drain pump turn on when the unit is powered off?
  • Does the gravity drain have a sensor for draining?
  • Can a pump model be used as a gravity drain model?
  • What is the drain line fitting on the pump model?


The gravity drain and pump UC-15I Ice Makers models are identical other than the following noted differences:

  • Models UC-15I and UC-15IO are gravity drain models, which require a drain hose pitched down from the outlet at the back of the unit to the sanitary sewer connection.
    • Gravity drain models are supplied with a drain hose for gravity draining.
  • Models UC-15IP and UC-15IPO have a built-in drain pump to pump water up to a drain point, such as a sink.
    • A pump model must be used if a gravity drain is not possible.
  • Both drain methods require routing to an open site drain with no possibility of backfeeding of drained water.
  • Do not connect directly to a drain line as bacteria from the drain line may contaminate the ice maker.
  • When evaluating gravity versus pump models, the location of the drain site in relation to the drain connection is the most important factor to consider.
  • If the drain site is above the drain connection, then select a pump model.

Gravity Drain Considerations

  • The ice maker drain connection is approximately 5" (127) from the floor.
  • All horizontal runs of drain line must have a 1/4" (6) per 12" (305) fall.
  • With the power off, this model drains on its own with no sensor involved.

Drain Pump Considerations

  • Drain pump models have a maximum rise of 12' (4 m) and a maximum run of 100' (31 m).
  • Drain pump models likely require an air gap device to prevent backflow of drain water into the unit between the unit and the drain receptacle. Refer to local code for specific information.
  • The drain pump discharge line must terminate at an open site drain.
  • The drain pump is sealed.
  • With the power off, drain pump has a sensor based off water pressure that turns the pump on, pumps water out, and turns the pump off (as long as the home electrical supply is on).
  • Drain pumps make additional noise and run more with heavier use.
  • To use a pump model as a gravity drain unit, remove the pump, refer to UC-15I Ice Maker Drain Pump Addition or Removal.
  • The pump model has a barbed fitting for the drain line to push on to. A clamp (not included) may be added if desired.

Contact a Local Dealer for further sales information.

See also, UC-15I Undercounter Ice Maker Noise.



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