Installing Condensate Pumps in Mini Split Systems

 Dec. 10, 2024      Jeff Rosenblum

There are two ways to go about managing the condensate produced from mini split systems. The first method is gravity drain. This is simply and pipe running at a downward slope to a drain or exit point. This is the easiest way to dispose of condensate.

The second method is to use a condensate pump. Connecting a condensate pump to a mini split can be tricky if there is confusion with the wires. Let’s start off by explaining the wires and what they do.

On a Mitsubishi unit, wires S1 and S2 are the line voltage. S3 is the communication line. In Breeze33 units, wires 1 and 2 are line voltage and 3 is the communication. The communication path uses S3 and S2 (or Breeze 3 and 2). S1 is always 110vac.

Most pumps are wired 240vac so they should be connected to terminals S1 and S2. If you want to use the built-in safety switch found in most pumps, you must only break the S1 wire. This is because of the communication path between S3 and S2. If S2 or S3 is used for the safety circuit, it can result in a communication error. There are other ways to connect the safety circuit, but this is the most common.

Other methods are breaking a thermistor wire (on Mitsubishi units that use a branch box) or if the unit has a built-in overflow jumper wire.

As always, if you need assistance please call the Famous Supply HVAC Tech Support Department at 330-475-8230.

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