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 …
… or this Foxboro pneumatic proportional plus integral (PI) controller …
… or this 1970’s vintage central control panel (the state of the art about the time I entered the industry).
Just the other week, I was in a building down in San Francisco that had originally been built in the 1960’s by Bethlehem Steel as their headquarters on the West Coast.
That was of unique interest to me because my grandfather on my mother’s side was a welder for Bethlehem Steel in their Johnstown Pennsylvania plant around that time; who knows, maybe he made some of the welds in the steel for the building when it was being fabricated back then. (The picture is from one of the elevators; they feature different vintage photos related to the building’s history).
The central plant in the facility had been recently upgraded from the original system. But when we got to the basement mechanical space, I was treated to a few more legacy control components, including this 2-pipe indicating temperature transmitter …
… and another central control panel.
The last picture is an interesting juxtaposition of technologies; the two monitors and the black box behind them (a PC) contains many orders of magnitude more information than the legacy control panel behind them. But I still have a soft spot for the legacy panel and was glad to see that it had been retained when the plant was upgraded.
My reason for bringing all of this up is that about a week ago, Steve Briggs, one of the other FDE engineers that I have the privilege of working and teaching with on occasion, sent me a picture from the field of an old seven day timeclock, the type of device we used to schedule equipment back in the “olden days”.
The device was simply an electrically driven clock with a dial that made 1 revolution every 7 days. Small, adjustable “trippers” were mounted on the perimeter of the wheel with little thumb screws and were shaped so that the side visible to you pointed to the time setting you desired and a little lever on the back of them would trip another lever (which is concealed behind the dial in this picture). The concealed lever, in turn, worked a mechanism that would open and close contacts, thus turning things on and off on a schedule.
There were typically two different types of “trippers” (some people called them “dogs” for some reason). On the visible side, they were different colors, usually black and silver so you could tell them apart.
On the back side, the shape of the lever was different with the difference being that one type of tripper would move the concealed lever in a way to turn close the contacts that the clock controlled while the other type of tripper would move the concealed lever in the other direction, opening the contacts back up. The contacts, in turn, could be used to turn equipment on and off on a schedule. You can still find devices similar to this in the hardware store, targeted at controlling the lamp on your end table.
The brass screws you see below the dial are one side of a number of contacts. In other words, if the picture were zoomed out a bit, you would actually see two rows of screws, with each vertical pair corresponding to an independent contact. In this case, I believe the last pair of screws on the far right would the power connection where you landed the 120 vac power to run the clock.
When I saw Steve’s e-mail and the picture, it immediately reminded me of my very first exposure to the concept of persistence of benefits. In other words, it’s one thing to intend to have a building or system do something like operate on a schedule by providing a time clock with a wiring diagram and control sequence that indicates that the clock should start or stop a piece of machinery or cause a certain function to happen at a certain time of day on a certain day of the week.
But it turns out that it is entirely different thing to have that design actually work and remain in operation over time, something I really did not realize until I ran into my first time clock.
Specifically, in the fall of 1979 or so Chuck McClure sent me down to do field work at Kent Library on the South East Missouri State Campus.
Chuck founded McClure Engineering in 1953, the year before I was born. And, based on the recommendation of Dr. Al Black, a mentor and friend from my Park’s College days, Chuck had taken a chance on an Airframe and Power Plant mechanic with some engineering courses to his credit and hired me as an HVAC field technician, which is how I got my start in this industry.
The reason for the field work in Kent Library was that the University was interested in installing some sort of supervisory monitoring and control system to help them understand how their buildings were running from a central location and to allow them to identify operating problems and ultimately, optimize the existing stand alone control systems based on what they were observing. This, of course, was the fore-runner of what we take for granted now in our Direct Digital Control (DDC) systems. But at the time, it was fairly cutting edge.
In those days, large buildings might have central control panels similar to the ones I illustrated above. (And sometimes, the gauges were even right). But very few if any sites with multiple buildings, like a college campus for instance, had all of the buildings networked together and visible from a central location. So, it was exciting to be involved in a project like this, even though at the time, I did not fully comprehend how big a deal it really was. But eventually, Kent Library would become my first design for what we now would call a DDC system (under the watchful eye of Chuck and Al of course).
At the time of the site visit, my goal was to develop field verified diagrams for the existing interlock wiring and pneumatic control systems serving the equipment in the library. Thus, I found myself opening up control panels, junction boxes, motor control centers and wireways tracing out colored wires and copper tubes and trying to figure out what they were connected to and what all of these funny, new to me, electrical relays, switches, and pneumatic gizmos did.
The original library was dedicated in 1939. But all of the equipment I was looking at had been installed in a 1968 project that had been done by Chuck himself. So, I had a pretty good resource at my disposal in terms of trying to understand the design intent of the facility.
One of the things that had attracted me to McClure Engineering when I interviewed there was that they had always had an interest in energy conservation and the responsible use of resources, even before the first energy crisis hit in 1973. In the course of the interview process, Bill Coad pretty much said to me what would eventually become his Energy Conservation is an Ethic paper and as a result, I left the interview inspired in a way that changed my life.
One of the reasons Chuck and the University had targeted Kent Library for the pilot for a supervisory control system was that it was fairly energy intensive due to the archival storage nature of the application. If you are playing the archival storage game, one of the things you are trying to do is hold very stable temperature and humidity levels and keep the air very, very clean. Avoiding damage by light and vibration are also important. It’s really pretty interesting (in a nerdy sort of way) and the ASHRAE Handbook of Applications contains an entire chapter dedicated to the topic.1
All of those requirements tend to mean that the HVAC systems in archival storage facilities need to run round the clock, especially in the rare book areas, even if nobody is in the facility. But if nobody is in the facility, then one thing you don’t have to do is ventilate; i.e. introduce outdoor air to manage the contaminates introduced into the built environment by human activity.
In climates like Cape Girardeau, Missouri, ventilation loads can be significant because it can be very cold and dry in the winter and very hot and humid in the summer, as illustrated by this bin data plot I created using the Pacific Energy Center psych chart tool.2
As a result, one of the things that Chuck had done in his 1968 control system design was include a time clock that would shut down the minimum outdoor air that was brought into ventilate the building during the unoccupied hours. In other words, even though the systems could not be scheduled, the ventilation could and Chuck designed the clock into the control system to perform that function
Since I was using the original design documents and control submittals for the 1968 project to guide my field effort, one of the things I was looking for was that time clock because we planned to take over that function with the central monitoring and control system. Doing so would allow us to change the schedules by remote commands from the central location rather than by having to put out a work request to have one of the campus technicians visit the building and move the trippers around on the time clock every time the school was not in session or a schedule changed.
Having to do that every once-in-a-while doesn’t sound like a big thing until you consider the number of buildings on a college campus and that each building might have multiple time clocks in it. The overview above will give you a sense of that. Each of the little markers is a building. Kent Library is the yellow marker to the upper right of the clump of red markers at the lower left side of campus.
Eventually, one of the control panels I opened up contained the clock I was looking for. But the problem was that it looked just like the clock in the picture Steve sent to me; i.e. there were no trippers on it. That meant that currently, at the time of my visit, one of Chuck’s energy conservation features was not delivering the intended functionality.
But it was worse than that. There was a small manila envelope sitting in the bottom corner of the control panel. Even thought it was not very large – maybe 1 inch by 2 inches – it was kind of heavy. I broke the seal and opened it up to discovered that it contained the missing time clock trippers. There were 14 of them to be exact; 7 silver ones and 7 black ones.
That was enough of them to program one on and off event for each day of the week, just as Chuck had specified. The problem was, that since they had never been installed on the time clock the ventilation that Chuck had intended to be shut down for about 6 to 8 hours a day on week days, longer on the weekend as I recall, had not happened, not even once, since 1968.
The good news there was that we had just found a significant opportunity to reduce the operating cost of the facility, which would definitely help justify our project. The bad news was that it should have been happening all along.
The incident certainly caught my attention, Chucks too. And as a result of the incident and other insights we were having as a company about the how buildings were being operated, Chuck tapped into my A&P Mechanic background and had me start developing checklists for some of our new projects.
We applied the lists as a tool to help us prevent problems like the one I had uncovered that day in Kent Library. We also made an effort to train the operators about the features of our designs, especially the ones that would help save energy.
And we worked with our clients to help them understand how to monitor the performance of the facility on a day to day basis by using average daily consumption analysis and supplementing their stand-alone control systems with remote monitoring systems like the one I was starting to work on for Kent Library.
As I look back on it now, I realize that a lot of the things we were doing to try to address the lack of persistence of the benefits of Chuck’s design are the same things that are suggested today in the commissioning industry to help ensure the persistence of the benefits of commissioning.
At the time, the commissioning industry was just starting to emerge in Canada and the United states. But since I had not heard about the commissioning industry yet, I thought that all we were trying to do was operate the building properly.
David Sellers, P.E., Senior Engineer
Facility Dynamics Engineering
Visit FDE’s commissioning resources website at http://www.av8rdas.com/
Visit my non-technical blog The Other Side of Life at https://av8rdaslife.wordpress.com/
- It’s Chapter 33 in the most recent, 2015 edition of the Application Handbook. If you happen to be in the Bay Area, there are copies of different editions of the handbooks available in the Pacific Energy Center Resource Center. I think you can even check them out if you want to.
- To do the bin part, you need to upgrade the basic chart tool (which is free) to the professional version. But Ryan Stroupe, the Measurement Tools Program Coordinator that I teach with at the PEC, worked out a deal with Hands Down Software, the chart developer, that allows you to upgrade to the professional version at a 30% discount from the normal price.
A Field Perspective on Engineering 