The on-line program you are about to enter should be
considered an alpha release.
Every effort has been made to ensure accuracy.
However, occasional bugs may decide to visit. If you
experience or recognize any type of error, please contact Russ
Marcks with the details of that error. Include the
error message as well as the data values used to generate the
This program has minimal error trapping capability at this
time. It is currently possible to enter inappropriate
values resulting in negative latent coil loads, negative
condensate production or inappropriate values of
psychrometric properties. If you receive any of these
conditions, chances are one or more of your input values are
There are no known bugs at this time.
The current program will only calculate process loads
given entering and leaving conditions. I fully intend to
provide the option to calculate leaving conditions given
entering conditions and loads as well as entering conditions
given leaving conditions and loads.
No warranty, either expressed or implied,
is given with respect to the accuracy or the sufficiency of the
information provided hereby, and the user must assume all risks
and responsibility in connection with the use thereof.
Use this calculator to determine the conditions of a cooling
process. The user must select either site elevation
(default selection from which an average barometric pressure is
calculated) or barometric pressure in psia or inches of mercury
(In. Hga.). The default values for these selections are
Sea Level Pressure: 14.696 psia (29.921 In. Hga.) (Default when psia or Hga is selected)
Average Barometric Pressure in Dayton: 14.175 psia (28.860 In. Hg.)
Site elevation for Dayton, OH: 997 ft based on ASHRAE HOF. (Default when Elevation is selected)
Your own value of elevation or barometric pressure for your area.
Once you select how to define barometric
pressure, you may override the
default value by simply entering your own value.
Select the process quantity to calculate and the method used to measure
humidity conditions. (Currently,
only process loads are available.)
If finding process loads, both entering and leaving humidity
conditions must be entered and measured using the same metric.
User may choose to include fan heat in the calculations. If so, enter
either fan static pressure and static efficiency or fan total
pressure and fan total (mechanical) efficiency. DO
NOT MIX STATIC AND TOTAL MEASURES. Select if the
motor is inside or outside the air stream.
Enter the volumetric flow rate of the air stream and select whether it
is measured at the entering or leaving point of the process.
Enter the air stream temperature(s) and humidity values as
appropriate. If entering relative humidity, enter as a
percentage, not a decimal.
Do not enter condensate value, the value(s) you wish to calculate
or coil ADP, Bf & GSHF. These values are
calculated. In Internet Explorer and Netscape 6.x or greater, these boxes will appear
If all input is valid, the displayed results may be used as
intended. If the results are not valid, you will receive
one of several error messages. These messages are described
at the bottom of the calculator page.
The table of psychrometric values are those one would find on any
psychrometric chart. If you desire or need additional
thermodynamic properties for the air conditions in your example,
try our Psychrometric Properties
This website strives to be cross-platform, cross-browser and ADA compliant. This site has been tested with the latest versions of Internet Explorer, Mozilla-based browsers, Opera, and Konqueror, but has not been tested with text-only browsers. This site is designed for viewing at 800 x 600, but is best viewed at a resolution of 1024 x 768 or greater. If you have difficulty viewing this site, contact the webmaster.
This web site is maintained by the Dayton Chapter of the American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc. (ASHRAE). It does not present official positions of the Society nor reflect Society policy. ASHRAE chapters may not act for the Society and the information presented here has not had Society review. To learn more about ASHRAE activities on an international level, contact the ASHRAE home page at http://www.ashrae.org
Website questions or comments? Contact Russell Marcks
Last Updated 04 Jan 2015