Formula
ΔT = Return DB − Supply DB · target shrinks as return wet bulb risesMeasure DB/WB in the return ~6 ft upstream of coil; supply DB ~6 ft downstream. Avoid radiant influence from coil.
Measured ΔT
18.0°F
Target 19°F at 63°F WB
ΔT in normal range. System is moving heat as expected.
Reference
- Dry climate (55°F WB return): expect ~22°F ΔT
- Average (63–67°F WB): 17–20°F
- Humid (75°F WB): 14–16°F