Author Archives: David Sellers

Lags, the Two-Thirds Rule, and the Big Bang, Part 5

In Part 4 of this series, we explored the complex transportation lag that was the key challenge in terms of using a remote duct pressure sensor to control the large VAV air handling system in the case study building. In … Continue reading

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Lags, the Two-Thirds Rule, and the Big Bang, Part 4

In the previous blog post,  we looked at common lags that you might encounter in building systems in the general case. In this post, we will look at the particularly complex transportation lag that I ran into in the MCI … Continue reading

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Lags, the Two-Thirds Rule, and the Big Bang, Part 3

In the previous post, we took a look at why moving the sensor that controls discharge static pressure in a variable volume fan system out into the distribution system will save energy compared to controlling for the pressure at the … Continue reading

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Taylor Engineering’s COVID-19 White Paper

Just a quick note to let you know about a very timely, well researched, well-written, well thought-out and practical discussion of the COVID 19 crisis in the context of the HVAC systems many of us deal with as a part … Continue reading

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Lags, the Two-Thirds Rule, and the Big Bang, Part 2

In the previous post, I describes a significant emotional event I experienced in an early attempt to use a remote duct static pressure sensor to control a large variable air volume system. The remote sensor approach represented an application of … Continue reading

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Lags, the Two-Thirds Rule, and the Big Bang, Part 1

This string of blog posts started out as an ASHRAE Engineers Notebook Column.  But they got to long for that format, so I decided to post them here.  The story is an example of how I was mentored by a … Continue reading

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New Resources

Its been a while since I have posted and my (potentially annoying) holiday post has been sitting there for over a month.   All I can say is that I have been working on FDE’s commissioning resources website to add some … Continue reading

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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

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