Category Archives: Controls

Posts with information about control systems.

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

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

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

Posted in Air Handling Systems, Controls, Mentoring and Teaching, Pneumatic Controls | Leave a comment

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

Posted in Air Handling Systems, Controls, Mentoring and Teaching, Pneumatic Controls | Leave a comment

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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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

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

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

Learning about Relay Logic; What’s a Relay?

Author’s Note:  I edited this to put in pictures with better contrast for the relay images further down the post and for some reason, instead of just replacing the original post, the system put it up as a new post.   … Continue reading

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Control System Fundamentals

This post evolved to support a string of posts I will start next to support an exercise in one of the classes I am involved with at the Pacific Energy Center.  In those posts, we will look at how you … Continue reading

Posted in Controls, HVAC Fundamentals, Operations and Maintenance, Pneumatic Controls | 2 Comments

Economizers–The Physics of Linkage Systems

In the post before the previous, I was discussing an economizer performance problem in a facility we worked with as a class in Monterey California.  One of the problems was related to the mechanics of motion in the linkage system … Continue reading

Posted in Air Handling Systems, Controls, Economizers, Pneumatic Controls | Leave a comment