Author Archives: David Sellers

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

Posted in Uncategorized | Leave a comment

So Many Tools; So Little Time (Unless You Happen to Live in the Bay Area and are Looking for a Job Working with Them)

The picture above is a panorama shot of the tool lending library at the Pacific Energy Center.  As I took the picture, I was literally thinking so many tools, so little time, wishing I could spend some of my day … Continue reading

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Cooling Tower Flow Distribution and Variable Flow in Condenser Water Systems

One of my current obsessions is how subtle details regarding how you pipe a cooling tower can make a huge difference in how the flow is distributed.  I’ve been interested in that for a long time actually as the result … Continue reading

Posted in Condenser Water Systems, HVAC Fundamentals, Operations and Maintenance, Retrocommissioning Findings | Leave a comment

An Existing Building Commissioning Learning Opportunity

The picture above is a panorama I shot earlier this year in a recently renovated central chilled water plant serving a large high-rise office building in down town San Francisco. The people in the picture are students in the Existing … Continue reading

Posted in Retrocommissioning Findings | Leave a comment

The Persistence of the Benefits of Commissioning (Plus a Few Pictures of Legacy Instruments)

As you probably have noticed if you follow the blog, I love finding old instruments in my travels. I have even been lucky enough to save a few of them from the dumpster, like this resonant frequency-based tachometer …   … Continue reading

Posted in Controls, Mentoring and Teaching, Operations and Maintenance, Pneumatic Controls, Retrocommissioning Findings | Leave a comment

Resources for the Resourceful – Utility Analysis Spreadsheet Tool

Authors Note: Since the point in time when I published this post, some of the links have expired. So, I have gone through it and renewed them and also made a few edits. Linking to the Weather Data Depot in … Continue reading

Posted in Excel Techniques, HVAC Calculations, Operations and Maintenance, Resource List and other Resources, Retrocommissioning Findings | Leave a comment