COMMISSIONING OF HVAC SYSTEMS - seedengr.com

1 COMMISSIONING OF hvac SYSTEMSS tephen T. Burch, (912) 652-5318 BACKGROUND. The current guide specifications require the hvac COMMISSIONING to be accomplished by the construction contractoras part of the construction contract. However, the SavannahDistrict Engineering Division has determined that additionalmeasures must be taken to ensure that COMMISSIONING of hvac SYSTEMS for construction projects is successfully accomplished. To enhance our ability to provide completed hvac SYSTEMS whichfunction as designed, an IDT contract has been developed tofacilitate an independent COMMISSIONING process. The IDTcontract is being used as either a Quality Assurance tool or toprovide full COMMISSIONING services in lieu of constructioncontractor provided services during the construction phase.

2 Additionally, the IDT contract is being used to respond tocustomer needs for existing facilities experiencing poor hvac system CRITERIA. Specialized experience in design,construction, installation, and COMMISSIONING hvac SYSTEMS isrequired as preselection criteria. Capacity to accomplishmultiple simultaneous delivery orders and provide staff in thefollowing disciplines are required: Mechanical ( hvac ) Engineer, hvac Controls Engineer, Electrical Engineer, hvac SystemTechnician, and a certified TAB specialist. The followingelements were included in the Preselection Evaluation Perform functional performance tests for the following: pumps, chillers, cooling towers, VAV terminals, VAV air handlingunits, multizone air handling units, packaged air cooledchillers, air cooled condensing units, hot water boilers, steamboilers, fan coil units, unit heaters, steam/hot waterconverters, computer room units, hvac controls, energy recoverysystems, Perform a complete testing , adjusting, and balancing of Perform Pre- COMMISSIONING Checks, correct deficienciesdiscovered, and retest Construction consultation & New military facilities requiring hvac Improvements and repairs to existing hvac Preparation of technical documentation which supports detailinspection, testing , adjusting, balancing.

3 And trouble shootingof hvac system designs and installed Capacity to provide the following disciplines:Mechanical Engineer ( hvac )1 hvac Controls Engineer1 Electrical Engineer1 hvac SYSTEMS technician1 KEY TECHNICAL AREAS. The hvac COMMISSIONING IDT contract can beused in the following applications: Performing functionalperformance tests for typical mechanical equipment, performing acomplete testing , adjusting, and balancing of hvac SYSTEMS ,performing Pre- COMMISSIONING Checks, correct deficienciesdiscovered, and retest system , construction consultation &inspection, new military facilities requiring hvac SYSTEMS ,improvements and repairs to existing hvac SYSTEMS , preparation oftechnical documentation which supports detail inspection, testing , adjusting, balancing, troubleshooting of hvac systemdesigns and installed SYSTEMS , performing complete studies ofHVAC SYSTEMS , and producing plans and TO DATE.

4 Specific examples of IDT delivery orders issuedduring the spring and summer of 1997 have been documented and arepresented as follows:In April 1997 the first opportunity to use the IDT contractpresented itself on the Alter Dormitories project at SeymourJohnson AFB, North Carolina. The scope of work was developed forthe first delivery order and Scope of Work: Subject dormitories have a four pipe heatingand cooling system , with individual room Fan Coil units (FCU). Acentral energy plant provides chilled water and steam throughdistribution piping for eight dormitories. Steam is converted toheating water in the dormitory mechanical rooms. One airhandling unit in each dormitory supplies conditioned (heated,cooled, dehumidified) air or makeup/fresh air to each room at thefan coil unit.

5 The piping at the central chiller plant, for bothchilled water and condenser/cooling tower water has beensignificantly changed through a contract modification to allowfor the operation of the 4 pipe system during minimum demand3periods. Lack of enough heating and cooling capacity at thedorms was experienced. The IDT contract is being used toevaluate the contractor's TAB results. Specific activitiesincluded in the delivery order were the functional performancetesting of:- Pumps and piping from the chiller plant to four dormitorymechanical Cooling towers at the central chiller Air Handling Units at each of four Fan Coil Units in ten percent of all rooms in Steam/Hot Water Converters in four hvac Controls for AHUs, hot water for heat and chilled water(dormitory side).

6 Using the results of the performance tests, system adjustmentscan then be made as Through the use of the IDT a number of deficiencies in boththe waterside and airside SYSTEMS can be identified. By takingcorrective action on each deficiency identified, the systemperformance should be enhanced. The original contract containedHVAC COMMISSIONING requirements. However, the final TAB andcommissioning could not be conducted until all the dormitorieswere completed and several modifications to the Central EnergyPlant could be incorporated. By the time this work was completedit was mid-October 1997. The Fall temperatures precluded anymeaningful testing of the air conditioning SYSTEMS . Theconstruction contractor is scheduled to conduct the final TAB andcommissioning during the coming air conditioning season.

7 Therefore, work under this IDT work order has been delayed untilsummer of May 1997 a delivery order was issued on the IDT contract tocommission a study to determine the cause of insufficient coolingfor the C-130 Aircraft operations and Logistic Facility at PopeAFB, North Carolina. Numerous deficiencies were noted in thetesting Background Information. The C-130 Aircraft Operations &4 Logistic Facility was designed in 1993 and constructed in 1994. The building is approximately 2,035 square meters (21,900 squarefeet) in size. An exterior wall section consists of 100 mm(4 inch) split face CMU, rigid insulation, 200mm (8 inch) CMU,metal furring channels and gypsum wall board. The roof is metalconstruction with engineered metal roof trusses.

8 Roof insulationis attached to the bottom chord of the metal roof truss. Thebuilding layout includes general office/administrative areas witha Briefing/Conference Room, Operations Center, Ready Room, andStorage/Support Room. The hvac system serving the C-130 Operations & Logistics Facility consists of two medium pressureair handling units (AHU-3 and 4) supplying VAV boxes providingzone control of space temperatures. Each air handling unit isequipped with a chilled and hot water coil. Supply air quantityis controlled by a discharge damper in the supply duct. Each VAVbox is equipped with a hot water reheat coil. Steam is providedfrom the base central steam system and is converted to hot waterthrough a heat exchanger.

9 Chilled water is provided to thesystem by a remote air cooled chiller. Typically, AHU-3 has acapacity of 2,775 Lps (5,880 cfm) with eight VAV boxes and servesthe west half of the facility including offices, operations,Ready Room, and Storage/Support. AHU-4, with a capacity of3,840 Lps (8130 cfm), supplies seven VAV boxes and serves theeast half of he building, including briefing and administrativeareas. The facility is equipped with a full DDC temperaturecontrol system with a control panel for local access in themechanical room. The North Carolina Area Office reported thatmost of the heating and cooling problems occurred in the areasserved by AHU-3, especially the Ready Room and Storage/SupportRoom. It was also noted that AHU-3 would not run continuouslyand required manual start on a daily basis.

10 Inspection of theReady Room revealed it contains vending machines, microwavecookers, and computer work stations. The Storage/Support Roomhas roll-up door which is frequently used and the corridorbetween these two areas serves as a major entrance/exit for testing procedures . The IDT contractor was furnished a setof the design drawings and specifications, equipment submittals,and temperature control submittals for the project. A thoroughreview of these documents was performed to ensure conformity ofsubmittals to contract documents and to assure the designreflected industry standards in hvac SYSTEMS . An access code wasobtained from the installation temperature control engineer sothe DDC system could be tapped at the building.