Dry bulb temperature measures sensible heat only and says nothing about moisture. It is the number on a thermostat and the horizontal axis of the psychrometric chart. Techs measure dry bulb at return and supply to get the temperature split across a coil, and outdoor dry bulb is one of the two inputs to a fixed-orifice charging chart.
Return's 76 dry bulb and supply's 57, so we've got a 19 degree split, that's right in the window.
Also heard as
- DB
- dry-bulb temperature
- air temperature
Related terms
Wet bulb
The temperature a wet-wicked thermometer reads in moving air, lowered by evaporation in proportion to how dry the air is.
Sensible heat
Heat that changes the air's temperature, which you can read on a thermometer.
Split
The temperature difference between return and supply air across a coil, used as a quick health check.
Psychrometrics
The science of air and the water vapor mixed into it, used to design and diagnose heating, cooling and humidity control.