ASHRAE Psychrometric Chart 4+


Designed for iPad

    • $19.99

iPad Screenshots


The HVAC Psychrometric Chart app is the first truly interactive graphical psychrometric chart for the iPad, and it includes both IP and SI units. It is now optimized for iOS 16.

Using your finger, you can easily plot HVAC and other psychrometric processes on the iPad screen while you are out in the field, save the graphs, and then email the graph and results to yourself or clients. The HVAC Psych Chart app includes the following features and functionality:

1. Displays a fully customizable psychrometric chart in both landscape and portrait modes.

2. Allows you to customize the graph in many different ways including specifying the psychrometric chart line colors, chart background color, hide/display status of chart lines, point colors, process line colors, units of graph values, and the min/max limits of the chart.

3. Using your finger, you can plot as many points as you want on the screen. As you move your finger around the graph, the psychrometric properties at the top of the screen dynamically update . In addition, you can double-tap a point to display the point properties and then edit them.

4. Create psychrometric processes by plotting points then connecting them with process lines. Also, create custom labels anywhere on the chart.

5. After you have completed creating the chart, you can email a list of all the points and their properties along with a PDF of the chart, itself.

6. Create an unlimited number of psychrometric chart projects. Also, you can create templates that you can reuse over and over again.

7. Zoom in or out of the chart by "pinching" the iPad screen so as to view items in more detail.

8. Display sensible heat ratio (SHR) line

9. Display psych process line as curved along 100% RH line.

What’s New

Version 4.4

1. Optimized for iOS 16
2. Updated user-interface
3. Works with iPad Mini
4. Updated help

Ratings and Reviews

Marty731959 ,

Not ready for serious use

This app has the beginnings of a good app. But as is, it is limited in usefulness, and ASHRAE should not be selling this essentially beta version as a serious tool. Specifically the shortcomings are:

1. Needs an undo button.
2. SHR < 10% displays as a vertical line.
3. Needs enthalpy-humidity ratio button like SHR button.
4. Should be able to connect multiple lines to one point to show the correct process direction. For example, mixing point.
5. Need to add the ability to back up files.
6. Should add the ability to lock points so that they are not accidentally moved.
7. Would be nice to be able to delete lines by selecting them rather than going to the point menu to delete it.
8. When editing a point, there are times when the changes are not accepted.

If these changes are implemented, this could be a very useful app. However, as is, I wouldn't recommend purchasing it, and ASHRAE should make clear its limitations to people who are considering buying it. However, it appears that Carmel Software Corporation, who developed the app, is no longer updating it, and they don't respond to customer requests.

VariableK ,

Good app but needs work

Needs undo feature. Does not work well with Apple Pencil; selecting a state point causes the point to move; must use finger to select points. Connecting points with a process line will not carry forward the airflow rate; must be entered by hand for each point. Mixed air points are static individual points that are not tied to the air streams that created the mixed air point, such that if the conditions change then the mixed air point must be recreated. Occasionally, when pinching to zoom one of the state points will move even though my fingers were not near the point; something similar to this happens a couple of times on the training video from Carmel. The point properties form is not visible after zooming, appears to be off screen.

Wish List:
Create state points based on process loads.

Bottom Line: The app feels like a beta version for a psychometric chart program that had a very limited budget. In 2020 I expect software that is a bit more polished and more user friendly. And as one other comment stated, I would expect a little more from ASHRAE.

purgcfo ,

needs work

has potential, but is buggy and has stability issues. Also, needs a screen where points can be directly entered by typing, and I dont see any way to easily compute attributes of process lines between points.

App Privacy

The developer, ASHRAE, Inc., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Collected

The developer does not collect any data from this app.

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    Up to six family members can use this app with Family Sharing enabled.

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