Category Archives: HVAC Calculations

These posts discuss different HVAC calculations like fan power and energy, sensible load, etc.

Site versus Source Energy

Author’s Note:  I originally posted this in September of 2007 and used a report I had found at that time to develop some of the source energy factors I used in my illustration.   Since then, I have found a number … Continue reading

Posted in HVAC Calculations, HVAC Fundamentals, Resource List and other Resources | 2 Comments

Build Your Own Psych Chart – Creating the Data for the Saturation Curve and a Bit About VLOOKUP

So here I am, over a year later after starting this string, getting back to it.  All I can say is life happens and sometimes, because of that, you find that what you set out to do takes a bit … Continue reading

Posted in Excel Techniques, HVAC Calculations, HVAC Fundamentals, Psychrometrics | Leave a comment

A Free Electronic Psych Chart and How to Use It to Plot Basic HVAC Processes

Ryan Stroupe of the Pacific Energy Center recently worked out a deal that allows him to provide a free limited capability version of Hands Down Software’s electronic psych chart.  You can get a copy at this link and a overview … Continue reading

Posted in Air Handling Systems, Economizers, Excel Techniques, HVAC Calculations, HVAC Fundamentals, Psychrometrics, Resource List and other Resources, Weather and Climate Interactions with Buildings and Systems | Leave a comment

Retrocommissioning Findings: Reducing Boiler Purge Cycle Losses–How I Obtained My Results

This post expands on what I did in the final section of the last post to show how I arrived at the answers I arrived at. Before proceeding, I want to emphasize that what I am about to show is … Continue reading

Posted in Boilers, Hot Water Systems, and Steam Systems, Data Logging, Excel Techniques, HVAC Calculations, Retrocommissioning Findings | Leave a comment

Retrocommissioning Findings: Reducing Boiler Purge Cycle Losses

Greetings after another break in the action in terms of my posting rate.  As those of you who follow this blog know, sometimes, I get pretty busy and since writing this is not exactly my “day job’, my posting rate … Continue reading

Posted in Data Logging, Excel Techniques, HVAC Calculations, HVAC Fundamentals, Operations and Maintenance, Retrocommissioning Findings | Leave a comment

Unit Conversion Constants; Why Consistent Engineering Units are Important and Where the 3,960 in the Pump Power Equation Comes From

I recently received a question from one of the students in a class I am involved with about the Pump Power equation.  They were working with the equation in the form shown below, which is from the slide deck I … Continue reading

Posted in HVAC Calculations, HVAC Fundamentals | Leave a comment

Economizers–The Physics of a Mixed Air Plenum

I’ve been working on a post that shows how a scatter plot technique can be used to assess the performance of an HVAC airside economizer.  It’s based on comparing a plot of outdoor air temperature vs. mixed air temperature for … Continue reading

Posted in Air Handling Systems, Controls, Economizers, HVAC Calculations, HVAC Fundamentals, Psychrometrics | Leave a comment