SOW_-_FWJH069194A_UAV_Hangar_Bldg_1382_-_HVAC_Design_Deficiencies.pdf

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STATEMENT OF WORK:

30 May 2017

A. Furnish all investigations, engineering, materials, equipment and supervision necessary to complete the scope of work as described and specified below to repair HVAC Design Deficiencies in building 1382.

PART 1 GENERAL:

1.1. All work performed under this contract must be in accordance with the general conditions and technical specifications provided.

A. The Contractor shall abide by the General Condition which is a part of this Scope of Work and the templates can be provided by the Contracting Officer.

B. The Contractor shall abide by the Technical Specifications which are a part of this Scope of Work and may be obtained from the Contracting Officer.

SECTION DESCRIPTION

SEE TECHNICAL SPECIFICATIONS COMBINED

1.2 GENERAL: The purpose of the project is to correct all HVAC Deficiencies in building 1382.

A. ATTACHED PROJECT SKETCHES

1. ECN 5 Existing coil sketch - top_bottom split

2. ECN 5 Proposed coil sketch – intertwined

3. Elect drawings ECN-4

4. Mech drawings ECN-4 and ECN-5

1.3 OBJECTIVE: To correct all HVAC Deficiencies and install separate HVAC systems in building

1382.

Scope of work for North COMM room 214

1. Provide mini-split ductless system (TRANE model 4MXW6512 or equivalent) with 12,000 btuh cooling capacity.

2. Install indoor unit on most appropriate wall of COMM room 214 as directed by Owner. Include remote wired thermostat.

3. Route insulated copper condensate line to floor drain in Mech Room 216.

a. Alternate condensate route thru floor and down through Engine Shop terminating out exterior wall near grade.

4. Install matching condensing unit on concrete pad at grade near existing condensing unit CU-3, along North exterior wall of Engine Shop.

5. Route insulated refrigerant line set from condensing unit into Engine Shop, then up thru floor to

Indoor unit. Accommodate elevation difference.

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6. Provide power and control wiring service (208V-1Ph-60Hz) to indoor unit and condensing unit via a new circuit breaker in Panel L4. Size circuit breaker per manufacturer’s recommendations.

7. Charge refrigerant system and test.

8. After mini-split is installed, disconnect VAV-2-21 from the main supply air duct. Remove VAV-

2-21 and turn over to Owner.

a. Blank off branch opening in main supply duct.

b. Blank off transfer air opening in wall.

c. Tekplan will need to adjust the controls logic so that VAV-2-21 is removed from the control scheme all together and the # of VAV boxes for respective AHU-2-1 is modified.

This adjustment will remove VAV-2-21 from the cooling permissive for AHU-2-1. The static pressure control will be unaffected. Rebalancing of AHU-2-1 is not required.

Scope of work for South COMM room 252

1. Provide mini-split ductless system (TRANE model 4MXW6512 or equivalent) with 12,000 btuh cooling capacity.

2. Install indoor unit on most appropriate wall of COMM room 252 as directed by Owner. Include remote wired thermostat.

3. Route insulated copper condensate line to floor drain in Mech Room 253.

4. Install matching condensing unit on concrete pad at grade near existing condensing unit CU-6, along South exterior wall of Fabrication Shop.

5. Route insulated refrigerant line set from condensing unit into Fabrication Shop, then up thru floor to Indoor unit. Accommodate elevation difference.

6. Provide power and control wiring service (208V-1Ph-60Hz) to indoor unit and condensing unit via a new circuit breaker in Panel L7. Size circuit breaker per manufacturer’s recommendations.

7. Charge refrigerant system and test.

8. After mini-split is installed, disconnect VAV-2-20 from the main supply air duct. Remove VAV-

2-20 and turn over to Owner.

d. Blank off branch opening in main supply duct.

e. Blank off transfer air opening in wall.

a. Tekplan will need to adjust the controls logic so that VAV-2-20 is removed from the control scheme all together and the # of VAV boxes for respective AHU-2-3 is modified.

This adjustment will remove VAV-2-20 from the cooling permissive for AHU-2-3. The static pressure control will be unaffected. Rebalancing of AHU-2-3 is not required.

ECN#4 HVAC Modifications to Training Room (FCU-2-2 and Supplemental Cooling Units)

RFI-167 identified issues with frozen indoor coils primarily because of low airflow through FCU-2-2.

The Test & Balance report indicated airflow was 1271 cfm (design 1890 cfm)

1. FCU-2-2 is a dual compressor unit (each compressor is 6.25 tons). DMG temporarily disabled one compressor to keep unit running at low airflow. Coils would freeze up when both compressors run. The refrigerant coils are a top and bottom arrangement with independent refrigerant circuits.

2. Trane’s recommended air velocity across the cooling coil is 320 cfm/ton

a. Original design = 1890 cfm

b. TAB report actual = 1271 cfm

c. Trane’s airflow recommendation

i. One compressor @ 6.25 tons x 320 cfm/ton = 2000 cfm

ii. Two compressors @ (2 x 6.25 tons) x 320 cfm/ton = 4000 cfm

3. Since the nominal maximum rating of FCU-2-2 = 3000 cfm, we will not be able to use both compressors.

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4. The TAB report indicates 1271 cfm with a high static pressure drop. Items contributing to higher system pressure drop include:

a. Original location for FCU required relocating existing 6” fire line. The FCU was moved to adjacent storage room 266. The FCU was installed high to maintain head clearance. This required 2-90 degree elbows immediately upstream and downstream of the FCU to allow FCU to fit into the space.

b. Smoke dampers are installed in the storage room walls. These dampers are not required and could be removed, although they remain in place with damper blades open (actuator not connected). Due to the tight configuration, flow thru these open dampers appears to cause excessive pressure drop. Remove smoke dampers if FCU must be uninstalled to make modifications.

c. Tight elbows immediately next to open smoke dampers appear to cause additional pressure drop due to “system effect” normally associated with inefficient ductwork arrangement.

5. FCU-2-2 modifications

a. Disable one compressor in associated condensing unit CU-8 and keep as spare

b. Repipe refrigerant lines at FCU connection so both coils are connected to single refrigerant circuit. Otherwise air will preferentially flow thru dry coil and increase supply air temperature.

Trane indicated that 2 expansion valves would be required (one for each coil). Trane also said this modification would not void warranty.

c. Replace existing 0.75 hp FCU fan motor with 3 hp motor. The larger motor is required to overcome higher static pressure of as-built conditions. Trane will confirm if larger motor mounts would be needed. Provide adjustable sheave so fan can be balanced to 2000 cfm.

TRANE suggested not exceeding 2000 cfm so we can keep supply air temperature no higher than 60F at design (air entering coil) conditions.

d. TAB subcontractor shall retest FCU for new total airflow (2000 cfm). Supply duct does not need rebalancing. Provide access for TAB subcontractor to adjust fan sheave.

e. Modify DDC control sequence as shown on M701.

6. Training Rooms (224, 225 and 226) Supplemental Cooling

a. Since one compressor (6.25 tons) will be disabled on FCU-2-2, supplemental cooling will be required for the Training rooms to serve the original design requirements of 115 people in the space. FCU-2-2 with one compressor can serve about 50 people on a design day. Based on size of each Training room, the following supplemental cooling capacity is required when rooms are fully occupied.

i. Training Room 224 – 2.56 tons (use 2.5 tons = 30,000 Btuh)

ii. Training Room 225 – 1.68 tons (use 2 tons = 24,000 Btuh)

iii. Training Room 226 – 2.00 tons = 24,000 Btuh

b. Scope of work for Training Room 224

i. Provide mini-split ductless system (Mitsubishi, TRANE or equivalent) with 30,000 Btuh cooling capacity.

ii. Install indoor unit in ceiling grid of Training Room 224 as indicated on drawing M101

(final location as directed by Owner). Include remote wired thermostat and interlock with

DDC system.

iii. Install matching condensing unit on concrete pad at grade near existing condensing units along West wall of Tool Room.

iv. Route insulated refrigerant line set from condensing unit into Tool Room, then up thru floor to Indoor unit. Route insulated copper condensate line down thru floor then toward West wall of Tool Room. Run condensate down interior side of West wall terminating out thru wall near grade.

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v. Provide power and control wiring service (208V-1Ph-60Hz) to indoor unit and condensing unit via new circuit breakers in Panel L2 (indoor units) or Panel L5 (condensing units). Size circuit breakers per manufacturer’s recommendations.

vi. Charge refrigerant system and test.

c. Scope of work for Training Room 225 (same as Room 224, except):

i. Provide 24,000 Btuh cooling capacity

ii. Install indoor unit in ceiling grid of Training Room 225

d. Scope of work for Training Room 226 (same as Room 224, except):

i. Provide 24,000 Btuh cooling capacity

ii. Install indoor unit in ceiling grid of Training Room 226

ECN#5 HVAC Revisions to AHUs

Direct expansion (DX) refrigerant coils have experienced freeze up during low load operation and units shut down. This applies to all AHU that have variable air flow (AHU-1-1, AHU-1-2, AHU-2-1, AHU-2-2 and AHU-2-3).

1. AHU modifications

a. a. Refer to attached figure depicting Existing Coil Arrangement

i. The existing evaporator coils selected by TRANE are top/bottom split arrangement that is not appropriate for variable volume air flow and dual refrigerant circuits. During low cooling load condition, stage 2 (top) refrigerant circuit is off. Stage 1 (bottom) evaporator coil can experience freezing conditions because it has full refrigerant flow from compressor although half of the airflow bypasses through Stage 2 coil.

ii. Replace each evaporator coil with a new “intertwined” refrigerant coil.

b. Refer to attached figure depicting Proposed Coil Arrangement

i. The new “intertwined” coil will not bypass any airflow. See condensing unit modification for refrigerant flow control.

c. TAB subcontractor shall retest AHU for total airflow as indicated in equipment schedule on

M600. Supply duct does not need rebalancing.

2. Condensing Unit modifications (CU-1, CU-2, CU-3, CU-4, CU-5):

a. Hot Gas Bypass (HGB) valve to the Stage 1 compressor in each unit.

i. HGB will be piped to inlet of Stage 1 evaporator coil to prevent freezing at low loads.

b. HGB will require routing one refrigerant line between each AHU and the associated condensing unit.

c. Refrigerant piping will need to be evacuated and recharged with refrigerant.

3. DDC control modifications

a. Sequence of Control modified to reflect addition of HGB and staging of compressors.

b. Supply Air Temperature Reset control modified to minimize compressor cycling and better track room temperature conditions.

1.4 LICENSING AND CERTIFICATION

A. The contractor shall employ certified personnel and / or sub contractors with appropriate licenses and will provide their credentials to COR at the pre-construction conference.

1.5 QUALITY ASSURANCE

A. Contractor shall thoroughly check and test all parts and pieces to insure they are operating correctly and the complete system is working and meets the objective of a complete and usable

Page 5 of 5 28 Jul 2016 system. A final report shall be submitted to the COR detailing the testing accomplished for each system.

1. The facility shall pass and be regulatory compliant with all environmental laws for Federal, State, and Local criteria.

B. See Section 01400 of the General Conditions

1.6 SUBMITTALS:

Contractor will submit:

A. Product Data: Provide manufacturer’s data on systems.

B. Provide manufacturer installation instructions, wiring diagrams and all other publications that are required for a complete and fully functional system.

C. Contractor shall not order or begin any construction until the submittals have been approved by the Contracting Officer

D. See section 01300 Submittal of the General Conditions.

E. In additions to the number of copies under section 01300, provide one electronic copy to the

COR of all submittals, operating manuals etc.

1.9 WARRANTY:

A. System including all equipment and devices shall have a minimum of a 1 year full Materials and Labor Warranty, some items require longer and are indicated in specifications.

PART 2 PRODUCTS:

2.1 EQUIPMENT:

A. Any reference to a particular make and model are being used for example only. An equivalent or equal will be accepted for all items under this contract except Advantor. These shall be approved by the COR during the submittal process.

PART 3 EXECUTION

3.1 INSTALLATION

A. Equipment and materials shall be installed in an approved manner and in accordance with equipment manufacturers’ installation requirements.

3.2 FIELD QUALITY CONTROL

A. See section 01400 Quality Control of the General Conditions.

B. Provide all necessary testing to insure the system meets the manufacturer’s written instructions and that the system performs to the objective. All test report shall be provided to the

COR for record keeping.