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Controls Contracting -
Part 1 of 3
This is part one of a three-part series on controls contracting. This series focuses on the operations side of things, you know, the part that comes after the project is sold and turned over to the important people that make it happen, on schedule, within budget, and to the satisfaction of the customer! Seriously though, there is so much more to it than all that, and this series will barely scratch the surface, leaving out such matters as financial tasks, change orders, budget management, and so on. What this series will do, is give a basic outline of project tasks and milestones, from the preconstruction phase, through installation, to project closeout.
Okay, so the project is booked, a contract is issued,
and the salesperson has transferred everything that he/she has gathered on the
project to date, including project scope, plans, and specifications, to a common
file folder (real and/or virtual), for use by the Operations Department. What
happens now? Well, before anything gets installed, there’s a bunch of things
that need to take place, not of which the least important is the…
Turnover Meeting – Sales to Operations
A formal turnover meeting should be scheduled, to facilitate the transfer of knowledge of the project from the salesperson to the Operations Department (Ops Manager, Project Manager, Project Engineer, Draftsman, etc.). This meeting should be driven by the salesperson, who should have an agenda put together to follow, and should lead the meeting from start to finish, allowing for questions and open discussions throughout the meeting. This meeting should also serve the purpose of achieving “buy-in” from the Ops people, in terms of budget, hours allowed, schedule, and so on. The meeting needs to address all facets of the project scope, including all grey areas and uncertainties, and should be long enough to do so, but not so long that the attendees begin to lose focus. Rule of thumb states that for small projects, the meeting should last no more than half an hour, and for larger projects, never more than a couple of hours. If a project is so large and/or so complex that more time is needed, then it’s best to break it up into a couple of sessions held on different days. Know that this turnover meeting is meant to “debrief” the salesperson, however it’s certainly not the last opportunity to get information gathered from the “pre-booking” process, as you can always go back to the salesperson and ask additional questions, right? Well, let’s hope so!
Now that you have the plans and specs, and a basic understanding of the scope of the project, it’s time to get busy! Get yourself a set of highlighters, and start coloring the plans. Seriously. Or if you’re like me with a couple of creative kids of that age, have them help you! Begin by going through all of the floor plans and highlighting all of the equipment tags. These are the familiar six-sided bisected polygons that have letters in the top half to designate an equipment abbreviation (i.e., AHU for air handling unit), and numbers in the bottom half to give a unique tag to each and every piece of equipment (we hope!). The choice is yours, but I typically use yellow for highlighting equipment tags, and for any important notes that need to be flagged. Follow that up by highlighting all of the equipment associated with the tags. Again the choice is yours, but since orange is seemingly the most popular highlighter available aside from yellow (why is this??), I use orange for equipment. From there I use other colors to highlight control items that are shown on the plans (thermostats, sensors, dampers and actuators, etc), and to highlight pipe and duct systems as required.
Highlight the general notes and the key notes on each mechanical plan, as well as other miscellaneous notes that pertain to the controls. Next, go to the details sheets and scour the individual details for items that you’ll need to account for. There’s a tendency to skim over the details sheets (at least by me), however there’s usually some info “hidden” there that you’ll need to know, that might not be accounted for anywhere else. If there are piping schematics and/or ventilation riser diagrams, give these some well-deserved attention, as they tell their own story on how the systems are laid out and are designed to operate. Finally, turn your attention to the equipment schedules, and take note of equipment counts, making sure that they match your investigation of what’s actually on the mechanical plans. For each schedule, highlight important equipment attributes that you may need to have knowledge of for the engineering phase of your project. Items such as CFMs, GPMs, design temperatures, and electrical characteristics, hold a lot of value and tell a lot about how these mechanical systems are to operate, individually, and even interdependently.
If you’re fortunate enough to actually have equipment control schematic diagrams included on the mechanical plans, then these are your design documents, that will provide the basic structure on how you will proceed to generate your submittal package (control drawings, sequences, etc.).
If control schematics are not included as part of the design documents, then you’ll be required to rely heavily on the written specification. Either way, you need to study the spec and highlight the important stuff. Go through each major section of the controls portions of the spec, and flag all of the items that directly apply to the control systems design. Chances are that you’ll be using “a lotta yellow” here, as this is where you’ll find most of what pertains to the design and operational intents of the various mechanical systems, from a controls standpoint. Typically included are product and device specs, sequences of operation, and points lists. All of the information required to perform the hardware (and software) design of the control systems.
Once everything is highlighted and you’ve gotten a firm grasp on the scope of the project (virtually through osmosis), it’s time to start the next phase. If you have not adequately completed the above tasks, then go no further, turn back, and get it done! Nothing like jumpstarting the engineering halfway through this phase, only to get off to a false start and having to begin from scratch. Take it from me: it pays to take the time to understand the project thoroughly before you begin to tackle the engineering. If you’ve gotten through all of the above, then go get a drink of water, and please proceed to the next heading.
Engineering from Start to Finish
That last section was pretty lengthy…this one in comparison should be longer, but as I’m running out of room it’ll actually be somewhat shorter (thank goodness!). Anyway, now that you have a grip on the project, thus begins the task of “submittal generation”. Start by creating schedules for control valves, motorized dampers, and airflow measuring stations (as the job dictates). These schedules are to include information pertaining to the size, selection, application, and performance criteria of the items. Most controls contractors have standard spreadsheets that they’ve developed for putting together these schedules.
Now create sketches for the mechanical systems, and for each piece of individually controlled equipment. Add in the required sensors and transmitters (temperature, pressure, humidity, etc.), switches and two-state controllers (fan/pump status switches, safeties and limits…), and end devices (control valves, motorized dampers, VFDs, etc.), using the specified sequences, points lists, and control schematics (if provided) to account for all required components. From there, build the project-wide Bill of Materials, another spreadsheet that contains all of the unique components selected for the project.
With the above task completed, now determine the required I/O (inputs/outputs) for each system and each piece of equipment, and make your controller selections accordingly. Using your method of choice, develop point-to-point wiring diagrams for each. Organize your drawings in a sensible manner, and include the specified points lists for each system, as re-iterated from the specifications and expanded upon and/or modified to suit your design.
If the project is specified to be networked DDC (Direct Digital Control), show a “riser diagram” illustrating how all of the individual controllers are networked together to form the Building Automation System (BAS).
Package the drawings along with the written sequences and device data sheets, in a binder and send them off to the consulting engineer for their “seal of approval”, or the dreaded “revise as noted” stamp. Make your corrections as required, and move on to the next phase of the project…installation (next month).
Tip of the Month:
Beware of mechanical equipment submittals! While good intentions surely play a part in the generation of these documents, at times the controls-related information is inaccurate, incomplete, or omitted altogether. Rather than ramble on as to why this is (and getting myself in trouble!), I’ll simply state that it is often better to wait, if at all possible, for certain equipment (boilers and custom make-up air units come to mind) to hit the job site, and then grab the wiring diagrams shipped with the equipment, as these are more than likely guaranteed to be accurately reflective of the equipment they’re pasted on! For your submittal, better to leave out some of the details on how you connect and/or interface to certain pieces of equipment, until you know that the information you have is the information you need.
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