Your questions answered: The benefits and design strategies of custom packaged pump systems and mechanical rooms
Questions answered for the Aug. 19 webcast on custom packaged pump systems and mechanical rooms.
Jim Schlachter, business development manager, Grundfos Commercial Buildings, tackled unanswered questions from the Aug. 19, 2015, webcast on custom packaged pump systems and mechanical rooms.
Q: Will having a custom package save significant time, cost, and delivery time?
Jim Schlachter: In general, it does. Having the ability to work in a controlled environment with dedicated people allows for a quicker completion time. Most pump package facilities have crews who just build pump skids. They stock all of the necessary components so the procurement process is simpler, and being in a secure environment allows faster completion at less overall costs.
Q: What are the limitations or restrictions of the packaged system if it becomes necessary to replace its components?
Schlachter: A good packaged system manufacturer will incorporate working space requirements into its design. Many larger skids have service rails built in above the motors for servicing. Just as with other equipment (chillers, boilers), the pump package also has service clearances around the skid package. If these clearances are adhered to, future servicing and replacement can be easily accomplished.
Q: Do you perform phased drawing reviews with the vendor? If so, do you ever have them build a 3-D model for review in phases?
Schlachter: Many pump skid manufacturers have 3-D and Revit models available. For custom applications, several weeks may be required for models to be generated. But when the first model is generated, making changes is easy and effective. Getting with the pump skid manufacturer early in the design is key.
Q: Please outline the optimization process.
Schlachter: Every manufacturer has a different model for optimization. For pump systems only, it generally involves determining the overall number of pumps needed for the system, and determining the transition points where it is more efficient to run additional pumps at lower speeds. This requires mapping the system flow versus pump total dynamic head (TDH). This is a good starting point, but onboard controls are needed to continually monitor the actual system flow and TDH, and real-time adjustments must be made. This requires knowledge of pump curves and their operation, so only a handful of pump package manufacturers can achieve optimum energy efficiency.
As for central plants, each individual subsystem must be optimized (chillers, towers, pumps) as well as a total kW/Ton for the plant mentality. The pump vendors may be great at pump optimization, the chiller vendors at chiller optimization, but only a few companies can help generate a true system efficiency strategy, and link all phases of a central plant into one unified control algorithm. That is why in the presentation, it was mentioned that the more complex the system, the less vendors available, and working up front with the owner, engineer, and a few select vendors is critical for success.
Q: Several packaged systems shown require extensive structural enclosures for pipe and equipment support. Mechanical engineers typically don't want to be responsible for the specification, seismic issues, or code requirements for these structural items. Who becomes responsible for addressing all these structural items?
Schlachter: In general, the engineer should specify the seismic zone and site conditions required for the packaged unit. The qualified vendors will know how to design and integrate multiple pieces of equipment into a seismically-rated packaged solution. This should be part of the specification generated.
Q: Does it get ever complicated with so many variables of equipment, pipe sizes, controls, etc.?
Schlachter: Of course. The challenge of any system is finding a qualified vendor with this expertise, which helps everyone involved. It is no different than finding a qualified consulting engineer who can manage a design from initial design to commissioning.
Q: Are there any labor union issues with buying the packaged units?
Schlachter: There can be. That usually depends on the project. Many qualified manufacturers either employ or use union fitters and electricians during the critical phases of the central plant fabrication process. Using certified union pipefitters to build all the intricate headers and fitted spool pieces can usually enhance a project. Hopefully, the site union authority will accept union work from another area where the manufacturer is located.