Psychrometric Chart
Interactive psychrometric chart for HVAC professionals. Click anywhere to plot a state point, hover for instantaneous properties, and connect points to analyze processes.
For Licensed & Trained HVAC Technicians Only
This checklist is intended exclusively for use by licensed, certified, and trained HVAC professionals. It is not a DIY guide and should not be used by untrained individuals to perform repairs or diagnostics. The purpose of this checklist is to help qualified technicians maintain a consistent, step-by-step workflow so that no critical step is overlooked or skipped during service.
Psychrometric Chart
Based on a barometric pressure of kPa at sea level
Click anywhere on the chart to plot a state point. Hover for instantaneous properties.
Add a state point manually
No state points yet. Click on the chart or use the form above to add one.
How to read the chart
The X axis is dry-bulb temperature; the Y axis is humidity ratio (mass of water vapor per mass of dry air). The bold curve at the top-left edge is the saturation line (100% relative humidity); air can't hold any more moisture above it.
- Grey curves — constant relative humidity (10% … 90%).
- Cyan dashed lines — constant wet-bulb temperature.
- Purple dashed lines — constant specific volume.
- Amber lines — constant enthalpy.
All math uses the ASHRAE Handbook of Fundamentals (Hyland-Wexler saturation, full psychrometer equation for wet-bulb). Pressure is configurable for high-altitude work.
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