On a typical cooling system, techs expect a split around 16 to 22 degrees F, lower in humid weather because more of the coil's work goes into removing moisture. A low split suggests low charge or too much airflow; a high split suggests low airflow. Techs also talk of condenser split, the gap between condensing temperature and outdoor air. Split is a starting clue, not a charging method.
Split's only 9 degrees, return 78 and supply 69, put gauges on it and check the airflow too.
Read split with probes close to the air handler, not at a far register, or duct gains in a hot attic will shrink it.
Also heard as
- temperature split
- delta T
- TD
- temperature drop
Related terms
Dry bulb
Plain air temperature as an ordinary thermometer reads it, kept dry and out of direct sun.
CFM
Cubic feet per minute: the standard unit of airflow through equipment, ducts and outlets.
Starved
Describes an evaporator not getting enough refrigerant, so part of the coil runs warm and superheat is high.
Gauges
The manifold gauge set techs connect to service ports to read system pressures, saturation temperatures and charge.