Did You Know that with the new condensate pumps supplied with the Liebert units and possibly other pump purchased from the Supply Houses have been redesigned?
They use more plastic parts in the pump float assembly to prevent loss of movement to the float switches due to corrosion. Condensate pumps have two switches located under the cover. The first is the larger of the two and is to operate the pump motor. This float is normally connected to the larger of the two switches since this switch carries the larger of the loads to supply power to the pump motor. This should be the first switch to activate as the water level increases in the pump reservoir. The second float switch is the High Level switch and is smaller in size. This switch is normally wired in series with the condensing unit control circuit to shut down the unit or connected to a control board and will alarm in the event of high water level in the pump reservoir.
The high level switch can be set up for two different operations. You can choose the N.O. (normally open) or N.C. (normally close) function. By changing the wires on the micro switch to N.C. (normally closed), it causes the switch contacts to open when the water level rises, de-energizing the control voltage to the condensing unit. To wire the switch to N.O. (normally open), the switch contacts will close on the rise of the water level and will be used to send an alarm to the control board. On the Liebert Mini Mates, this high level switch is to be wired in parallel with the high level switch in the condensate pan of the indoor unit. Either of these float switches will generate a High Level Alarm on the display of the Liebert interface panel located on the wall. In the event of an alarm, both switches should be taken in consideration to be causing the alarm and checked thoroughly.
The condensate pumps come in a variety of shapes, sizes, voltages and types. There is a type of condensate pump that is used for high temperature applications. The condensate pump will have hot water entering the reservoir from a humidifier in the drain cycle of the cylinder during normal operations of the humidifier cycle. There are other pumps that have smaller reservoirs for use in applications where the fan coil unit may be installed close to the ceiling tile.
It has been discovered recently these pumps have had problems with nuisance alarms created when the high level switch is set too close to the operation of the pump switch. This is dew to the design and setup of the condensate pump assembly from the factory. The switches are so close that sometimes the high level trips before the pump operates. This can be corrected by slightly bending the metal tab up of the alarm micro switch so the float does not come in contact with the metal tab until the water level passes the float of the pump operation switch. Care must be taken not to bend it too high as this will cause the pump reservoir to over flow. The pump must be checked several times by adding water to the reservoir, preventing the motor from operating and the high level switch to trip correctly.