So, just got back from vacation to find much of my basement covered with a decent amount of water. Discovered my condensate pump stopped working (worn float) and overflowed for probably most of the week.
The pump has a safety overflow cut-off switch but it was never set up and so I finally did that (or tried at least) once I replaced the float and cleaned up the mess. Problem is the shut off does not appear to function. The pump is a Diversitech CP-22 with three terminals (com, run and alarm). I separated 2 yellow wires connecting the t-stat and outdoor unit and connected the t-stat wire to the provided lead wire to the com terminal at the pump and then connected the second lead wire from the run terminal at the pump to the yellow wire from the outdoor unit. Turned everything back on and all appears to work fine except the cut-off feature. T-stat calls for cool, condenser kicks on outside and house cools normally to set temp. The pump functions fine when full but when I tried to test the overflow feature by manually filling it with water faster than it could pump it out, the pump just overflowed and never shut the system off although the red alarm LED was lit up.
What did I do wrong here or could this be a faulty switch? The pump is at least 6 years old.
Best Answer
The correct wiring scheme for shutting down the AC completely is to break the 24v red wire (low voltage) coming from the t-stat bundle and then wire it in to the (COM) terminal of the pump. Then attach the second lead to the (RUN) terminal at the pump to the second red wire going to the control board/transformer. The (ALARM) terminal of the pump is intended to attach an audible alarm device that would be tied into the red low voltage t-stat wire. The previous wiring scheme will also work but only shuts down the outside unit's compressor, however the fan will continue to run.