Engineered Systems - April 2008 - (Page 32)

HVACRDesignerTips BY AMANDA MCKEW DESIGN REVIEW / DESIGN BUILD Commercial and Public Buildings Equipment type: Rooftop unit (RTU-1), DX cooling with gas heat Equipment designation: RTU-1 Barcode designation: 111111 Area served: One-story office space Equipment location: Rooftop • Has consideration been given to future expansion? ❍ • Has pressure testing of pipe distribution been determined ❍ in scope of work? • Has system flushing been determined in scope of work? ❍ • Has condensate drain piping been addressed? ❍ ❍ ❍ ❍ ❍ DESIGN REVIEW [Y] [N] • Verify there is adequate outdoor ventilation. ❍ ❍ • Spot-check air quantity based on cfm/sq ft. ❍ ❍ • Spot-check heating capacity based on Btuh/sq ft. ❍ ❍ • Create a system flow diagram to assess static pressure sequence of operation, condenser water, and/or chilled water pressure drops. ❍ ❍ • Spot-check fan total static pressure. ❍ ❍ • Confirm DX coil is piped correctly per manufacturer’s piping requirements. ❍ ❍ • Review control drawings and specifications to confirm unit space temperature setpoints are specified. ❍ ❍ • Review control drawings and specifications to confirm unit space humidity setpoints are specified. ❍ ❍ • Review control drawings and specifications and confirm unit space temperature high/low alarm limits are specified. ❍ ❍ • Review control drawings and specifications to confirm alarm sequences are specified. ❍ ❍ • Review control drawings and specifications to determine if unit will operate through the BAS/BMS. ❍ ❍ • Spot-check that there are adequate floor drains and funnel drains around unit. ❍ ❍ GENERAL CONSIDERATIONS/REQUIREMENTS [Y] [N] • What are the necessary installation permitting and operation permitting requirements? ❍ • Have insurance certificates been submitted to building owner? ❍ • Will record drawings be submitted electronically along with one paper copy? ❍ • Will there be an extended warranty on the equipment? ❍ • Will there be a service contract submitted for the RTU?❍ • Will the RTU O&M website be included along with electronic copy or O&M manual and two paper copies of manual? ❍ ❍ ❍ ❍ ❍ ❍ ❍ DESIGN REVIEW AND TRICKS OF THE TRADE • Create an airflow diagram indicating cfm, air changes, and space pressure. • Confirm there is safe access to the equipment. • Confirm the manufacturers’ recommended clearance exists around the equipment. • Consider that routine maintenance can be achieved without shutting unit down. • Attach equipment schedule and design criteria to checklist. • Attach sequence of operation to checklist. ELECTRICAL INSPECTION/REQUIREMENTS [Y] [N] ❍ ❍ ❍ ❍ ❍ ❍ ❍ • What are the electrical requirements for the new RTU? ❍ • Is there adequate electrical power to meet new electrical load from RTU? ❍ • Is there adequate electrical power coming in from the street? ❍ • Identify electrical scope of work required with RTU. ❍ • Will emergency power be a requirement for the new RTU? ❍ • Are electrical connections tight and secure? ❍ • Have the fuses and wire sizes been checked and verified? ❍ • What electrical system components (existing conduits, etc.) will require removal, reinstallation, and/or relocation to accommodate new RTU? ❍ • Are there existing electrical code issues that should be addressed at this time? ❍ REFERENCE • 2008 ASHRAE Handbook – Applications, Chapter 1, “HVAC System Analysis & Selection,” and Chapter 45, “Unitary Air Conditioning & Heat Pumps.” • 2007 ASHRAE Handbook – Applications, Chapter 3, “Commercial & Public Buildings Systems.” • 2005 ASHRAE Handbook – Fundamentals, Chapter 35, “Duct Design,” and Chapter 36, “Pipe Sizing.” NOTE ❍ ❍ • Refer to equipment manufacturers’ literature for additional data and requirements. • Refer to building owner standards and guidelines for additional criteria.ES If you have any comments, suggestions, or questions regarding this designer checklist, contact Amanda McKew at amckew@ rdkengineers.com. This column is meant to provide some basic guidelines for good design. Always consult all necessary codes and resources relevant to each particular project. HVAC INSPECTION/REQUIREMENTS [Y] [N] ❍ ❍ ❍ ❍ • Has selection of RTU been approved by owner? ❍ • Has the minimum gas pressure been determined? ❍ • Verify that gas piping is complete and correct. ❍ • Can the RTU be installed with access for maintenance? ❍ • Can the RTU be installed without removing other HVAC, electrical, plumbing, communication, and/or fire protection distribution or equipment? ❍ ❍ 32 En gi neer ed S y stem s April 2008

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Engineered Systems - April 2008 Contents Editor’s Note Back2Basics HVAC Challenge Case In Point Commissioning Building Automation Energy Wiz HVACR Designer Tips This Time, Water Cooled Was All Wet Cleanroom Design In 10 Easy Steps It's Not The Heat, It's The Humidity Issues & Events Computers and Software Products Glossary Classifieds Advertiser Index Tomorrow’s Engineer

Engineered Systems - April 2008

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