Approach and Delta-T Diagnostics
Condenser approach and supply/return delta-T with band labels.
Example
You enter
- Outdoor air (°F) 90
- Condenser saturation (°F) 105
- Supply air (°F) 55
- Return air (°F) 75
You get
- Approach 15 F
- Delta-T 20 F
Details, formula, and sources
Approach = T_liquid_line − T_outdoor (cooling) or T_supply − T_outdoor (heat-pump heating). Delta-T = T_return_air − T_supply_air. Targets compared against manufacturer commissioning guide ranges.
Manufacturer commissioning guides by name.
Free at each manufacturer site.
Estimate. AHJ and licensed mechanical contractor govern. ACCA Manual J / D / S supersede rules of thumb.
Field names used by the API: outdoor_F, condenser_saturation_F, supply_F, return_F, approach_F, delta_T_F
- Typical delta-T 18–22 °F across the indoor coil for coolingmanufacturer typical