Author Archives: David Sellers

Creating a Third Axis In Excel

One of the challenges that came up when I was creating the time series graph of a 9,000 ton chiller plant load profile that I show in my previous post was that I wanted to plot data series that had … Continue reading

Posted in Data Logging, Excel Techniques, HVAC Calculations | Leave a comment

A New Application for Plot Digitizer (Plus a Quick Look at Hydraulic Variable Speed Drives and Chiller Free Cooling Cycles)

Those of you who know me know I am quite enamored with a little freeware application called Plot Digitizer.  If you are unfamiliar with it, the application allows to to create CSV (Comma Separated Value) files from the lines in … Continue reading

Posted in Boilers, Hot Water Systems, and Steam Systems, Chillers and Chilled Water Systems, Data Logging, Excel Techniques, HVAC Calculations, Motors, Operations and Maintenance | Leave a comment

A Control Logic Exercise and a Way to Get Comfortable With Navigating SketchUp Models

As many of you know, I have been experimenting with using SketchUp models as a way to teach EBCx techniques.  I frequently use them in my classes and also have started to post self-study exercises that are based on the … Continue reading

Posted in Controls, Retrocommissioning Findings, SketchUp Model Based Self Study | Leave a comment

A New Resource for Looking at Climate Data

So, some of you are probably thinking Thank God he has finally put something up that gets rid of that picture of him and Kathy on Christmas.  That did stay up for a bit longer than I had planned at … Continue reading

Posted in PowerPoint Techniques, Weather and Climate Resources | Leave a comment

Happy Holidays

Hoping you are having as much fun this holiday season as Kathy and I are having. Meanwhile, thanks for supporting the blog and Happy Holidays.    David Sellers Senior Engineer – Facility Dynamics Engineering

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Exploring Evaporative Cooling–Part 1

If you look at a psych chart closely, you will notice that the constant wet bulb lines are not exactly parallel to the constant enthalpy lines. Note that to make things more visually apparent in this blog post, for most … Continue reading

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

Universal Translator Workshop

Sorry to disappoint Star Trek fans, but this is not a workshop about a device used to decipher and interpret alien languages into the native language of the user.  Having said that, if you are into building systems commissioning and … Continue reading

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