Application Note: Dual Cool Pump Control

What is Dual Cooling? :

Dual cooling, also known as adiabatic cooling, works by using pre-cooling pads mounted on the outside of the condenser coil and running water over pre-cooling pads. The air drawn through the pads lowers the dry bulb of the ambient air entering the condenser coil. Lowering the entering ambient air allows for greater overall system efficiency. 

Use Case:

Occasionally we have customers with this type of application on their equipment looking for an effective control solution. 

Solution:

For this application, we'll interlock and control the water pump based on outdoor air temperature. We're also going to monitor the entering air temperature of the condenser.  The components needed are a SmartNode, a pilot relay such as a RIB with heavy-duty contacts rated for a minimum of 10A, and a Go/No Go current switch with an adjustable trip point. 

How does it work? 

• Configured as SSE the SmartNode switches 24VAC through relay 1 (configured as cooling) if the ambient temp is above the 72'F (adj) setpoint. Relay 1 is the interlock for the pump motor. 
• The 24VAC from relay 1 is then sent to the current switch and from the other side of the current switch to the low voltage coil on the (RIB) relay. 24V Common is connected directly from the SmartNode to the 24v com on the (RIB) relay.
• The current switch is installed on one of the three leads from the load side of the first compressor contactor to the compressor.  When the compressor contactor closes, the current switch senses current, closes the contacts and the 24VAC  is sent to the low voltage coil on the  (RIB) relay. The RIB relay then closes its secondary heavy-duty contacts sending power to the pump motor.

Mapping and Configuration :

• The following is used to configure the dual cool pump control.

Result:

•  The pumps on dual cool applications can be controlled and using a 75F SmartNode.