Author Archives: David Sellers

Flexible Flyer; a Holiday Story

Like it or not, you have probably noticed that I endeavor to do a “seasonal” blog post of some sort around the holidays.  Past topics have ranged from cute pictures of my granddaughters to snow crystals to George Hinke’s depiction … Continue reading

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Electric League of the Pacific North West Training Opportunity

This is a quick post to let you know that I will be helping to support a two day technical class for the Electric League of the Pacific Northwest.    The class will be a two day long technical class that … Continue reading

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Build Your Own Psych Chart–The Spreadsheet

A while back, I started a string of posts in memory of Bill Coad about how to build your own psych chart in Excel based on the basic psychrometric principles and equations.   This is what the completed product looks like. … Continue reading

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

The Functional Testing Guide

When I was working at Portland Energy Conservation Incorporated (a.k.a. PECI), one of the things that I helped to develop was the Functional Testing Guide.  At its heart, the guide was a compilation of functional testing strategies that were donated … Continue reading

Posted in Air Handling Systems, Boilers, Hot Water Systems, and Steam Systems, Chillers and Chilled Water Systems, Condenser Water Systems, Controls, Design Review, Economizers, HVAC Calculations, HVAC Fundamentals, Operations and Maintenance, Refrigeration | Leave a comment

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

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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