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HVAC Design Criteria and Guidelines EQUIPMENT, DUCTWORK, AND PIPING SUPPORT Equipment Support: 1. Floor and Housekeeping Pad Installation: Floor-mounted equipment must always installed on concrete housekeeping pad (or equivalent). Pads for air-handling units should be 6" high to allow for drain pan traps, while pads for all other equipment should be 4" high. Equipment should be anchored and grouted to housekeeping pads. 2. Structural Slab, Pier, or Foundation Installation: Cooling towers, tanks, chillers, and (sometimes) boilers are typically heavy enough to require a structural slab, pier(s), or foundations for support. Review each component with the project structural engineer to determine requirements. 3. Suspended Installation: For suspended equipment, structural steel framing to distribute the imposed operating loads without stressing building structural elements or causing damage to the building substrate is required This frame, which is then suspended from the building structure with vibration isolators an appropriately sized all-thread rod, serves an equipment platform. 4. Rooftop Installation: Equipment may be mounted on structural steel supports (the preferred method) or on continuous roof curb: a. Structural steel supports must be as detailed on the Drawings and their design requires the input of a structural engineer. The supports must allow for 36” clear space under the equipment for roof maintenance and replacement and include appropriate service walkways and handrails, steps, ladders, etc. b Continuous roof curbs tops are required to be 17" above roof surface to prevent leakage into the building in the event of roof flooding. Top of all roof curbs must be level, with pitch built into curb when deck slopes 1/4 of an inch per foot or greater. Often, structural steel reinforcement below roof to avoid stressing building structural elements is required…review with the project structural engineer. Ductwork Support: 1. Suspended Installation: SW master specifications require that ductwork hangers be fabricated of sheet metal straps in accordance with SMACNA's HVAC Duct Construction Standards - Metal and Flexible or of all-thread rod. a. Section 5 of the SMACNA manual provides numerous details for duct hanger methods with which the designer should become familiar. b. Where multiple ducts are routed together, they may by supported by a common trapeze hanger. 2. Vertical Shaft Installation: Vertical ducts must anchored and supported at each floor. See Section 5 of the SMACNA manual. 3. Rooftop Installation: Horizontal ductwork installed above a roof must be supported by roof support rails integrated with the building roof and structural members to both support the weight of HVAC Design Guidelines EQUIPMENT, DUCTWORK, AND PIPING SUPPORT 1 HVAC Design Criteria and Guidelines the duct and to provide vertical and horizontal anchoring against wind forces. Consult with the project structural engineer to determine requirements and provide details on the Drawings. Piping Support: 1. Suspended Installation: Piping systems and their support are classified as follows: Classification Type 1: Hot Systems Temperature Range Type 1A: 120250°F Type 1B: >250°F Type 2: Ambient Systems Type 3: Cold Systems 71-120°F Type 3A: 32-70°F Type 3B: <32°F Typical Service Applications Hot Water, Low Pressure Steam (15 psig), Steam Condensate, Low Pressure Boiler Feedwater High Pressure Steam (>15 psig), High Pressure Boiler Feedwater Condenser Water, Oil, Fuel Gas Chilled Water, Cooling Condensate Drains, Condenser Water with Waterside Economizer Cycle Liquid And Cold Gas Refrigerant, Chilled Water with Ice Thermal Storage System The guide master specifications establish requirements and offer options for each classification of piping support and the designer must carefully review and edit these specifications to accurately reflect project requirements. 2. Vertical Shaft Installation: Vertical piping must anchored and supported at each floor. [Note: In tall, concrete structure buildings, provide expansion devices every other floor to account for long term “creep” and shrinkage of the structure.] 3. Rooftop Installation: Horizontal piping installed above a roof must be supported by roof support rails integrated with the building roof and piping supports. Support in Seismic Zones: Review seismic requirements with the project architect/structural engineer. See Chapter 55, 2015 ASHRAE Handbook-Applications for design guidance. Responsibility for the design of manufactured equipment and/or field-fabricated components installed outdoors to withstand seismic loading, including comprehensive engineering analysis by a qualified professional engineer, using performance requirements and design criteria specified by the HVAC designer, should be delegated to the Contractor by the project specifications. This is a very specialized design process and is typically not within the skill set of most HVAC designers. [Note: Seismic design criteria may trigger building code requirements for “special inspections” by a third party for this portion of the work during the construction period. Support and Bracing for Wind Loads: Responsibility for the design of manufactured equipment and/or field-fabricated components installed outdoors to withstand wind loading, including comprehensive engineering analysis by a qualified professional engineer, using performance requirements and design criteria hereinafter specified by the HVAC designer, should be delegated to the Contractor by the project specifications. This is a very specialized design process and is typically not within the skill set of most HVAC designers. HVAC Design Guidelines EQUIPMENT, DUCTWORK, AND PIPING SUPPORT 2 HVAC Design Criteria and Guidelines 1. Project specifications should require that equipment and/or field-fabricated components installed outdoors must be fabricated and anchored to the ground or building structure, as applicable, to withstand a wind load imposed on the largest vertical or projected surface area at the maximum wind speed dictated by the applicable building code and based on the project location. 2. Outdoor piping and raceway is required to be anchored by using a U-bolt, strap, or other holddown device anchored at each support point. 3. Equipment and other components may be anchored by using structural frames, straps, or other hold-down devices anchored to foundations, structural supports, or roof curbs, as applicable. HVAC Design Guidelines EQUIPMENT, DUCTWORK, AND PIPING SUPPORT 3