Follow-up Materials for Maria
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The various versions of the PEC Chilled Glycol System Diagram that I have done are in this zip file. I also included the other PEC systems I have done a system diagram for just so you have them.
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This zip file contains the Davis Hall CW and CHW system diagrams. The CW "Teaching Version" diagram is the diagram with the temperature sensor in the wrong place and before the recommended valve replacements were made
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This is the presentation with the slides that show how a number of issues with the Davis Hall CW system became apparent just by drawing the system diagram.
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This is the AutoCAD RPBFP symbol that I mentioned.
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This PowerPoint has a number of pictures of check valves (slides 27-30) and also of a butterfly valve with the disc exposed (slide 20). The image file is a picture of a pallet with a NO and NC butterfly control valve where you can see the butterfly valve discs in both extreme positions.
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These files should give you a pretty good sense of what a pump coupling is like.
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Davis Hall Logic Exercise Materials
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This is the current version of the model behind the exercise.
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This zip file contains my system diagram, the contract document system diagram, and the contract document mechanical plan. One of the things I do in the exercise is contrast those three documents, which (hopefully) reveals some of the benefits of the system diagram approach we teach.
Note that my system diagram shows the controlling sensor on the wrong side of the tee. That is actually how it was being put in and one of the points I make is that developing and field verifying the system diagram helped us find that issue and correct it in a timely fashion. | ||
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These Excel files are versions of the logic diagram tool with cooling tower fan control logic in them. The davis_hall_cw_system_v4.xlsm file is specific to the exercise and shows the solution with a single control loop (which has the lag problem) and the solution to that, involving two loops with coordinated set points and the requirement for relative calibration.
The other file is what the logic looks like for a cooling tower fan with a two speed motor, which captures a lot of the savings you can achieve with a VFD but introduces some safety interlock requirements to prevent tearing up the drive system when you change from high to low speed. The relevancy is that in existing buildings, you will find this approach in place because that is how we did it before VFDs were as affordable as they are today. You may not be able to justify adding a VFD because the two speed approach captures much of the savings. But if the control tech providing a control system upgrade to DDC tried to control the two speed starter like a VFD, they could get in trouble. | ||||
Light Control Logic Exercise Materials
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This is the logic diagram tool with lighting control logic including a couple of ways to show a simple on-off light switch, a couple of ways to show a three-way switch, and a couple of ways to show a dimmer.
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These are files that I use to support the light switch dimming exercise. The PowerPoint is the physical wiring for different lighting circuits in ladder diagram format. The spreadsheet is the data behind the charts embedded in the logic diagrams that do a curve fit to create a linear lighting level increase.
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