2. Statement of Work - AHU-1 Repairs.pdf

Removal and Replacement of AHU-1 Chilled Water Coils Page 1 of 5

NLAE

Ames, IA March 23, 2022

Statement of Work (SOW) Project: Removal and Replacement of AHU1 Chilled Water Coils

Revision 1 dated March 23, 2022

GENERAL INFORMATION

1.0 Scope of Work: Replace AHU 1 chiller water coils (2) and reconfigure original supply and return plumbing to be correct (See photos titled 12505B22R0003 – AHU-1 Repairs – Pictures 3-22-22). Insulate coil with 1” fiberglass insulation.

2.0 Background: AHU 1 chill water coils are original to the building. They need replaced with new, the upper coil is irreparable. Onsite inspection required for contract to make accurate measurements.

New coils shall be angled to the drain side to assist draining. New plumbing shall have new valves, ports and gauges as the original layout.

3.0 CONTRACTOR REQUIREMENTS

Must have specifications are as follows:

Technicians preforming work shall provide evidence of a minimum of 3 years’ experience in coil replacement and coil welding.

Contractor shall remove all of the existing Chilled Water cooling coils for AHU-1 in the USDA National Laboratory for Agriculture and the Environment (NLAE).

Contractor shall replace all of the removed Chilled Water cooling coils for AHU-1 in the USDA National Laboratory for Agriculture and the Environment (NLAE) with coils of the following minimum specifications:

o Coils shall be furnished for cooling media per the attached Air Handling Unit and Chilled Water Cooling Coil Schedules. Coils shall be designed for (200) psig design pressure.

o Coils shall be the extended surface type consisting of copper or copper-nickel seamless tubing with a minimum wall thickness of 0.018 inch and copper, copper-nickel, or aluminum flat or spiral fins. Fin to tube bond shall be made by either mechanically or hydraulically expanding the tubes into the fin collars or continuously brazing fins to tubes. If the fins are attached by winding, under tension, the process shall compress the metal for a slight indentation of the tube at contact.?

o Coil headers shall be copper, copper-nickel alloy, or carbon or stainless steel having not less than 0.125 inch thick walls. Cooling coil headers shall have inlet and outlet nozzles having flanged end connection in accordance with ANSI B16.5 that are external to the unit housings.

Cooling coil headers shall have inlet and outlet nozzles. Cooling coil headers shall have inlet and outlet nozzles having flanged end connections in accordance with ANSI B16.5 or screwed end connections that are

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Ames, IA March 23, 2022 external to the unit housings. Individual coils shall have supply connections at the bottom of the coil and return connections at the top of the coil.

o Coil drains shall be ½” or ¾”.

o Each coil shall have threaded vent and drain holes that are sealed with threaded brass or bronze plugs. The cooling coil drain pans shall be suitable for draining water from either the vent or drain hole. The drains and vents do not have to extend through the unit housing; however, access to the vent and drain plugs shall be provided through access panels or doors in the housing. The coil inlet and outlet nozzles shall be on sides of the unit as indicated on the drawings.

o Seals shall be provided at the top, bottom, and intermediate channels to minimize air bypassing the coil surface. Diffuser plates and baffles provided to minimize stratification and coil wiping shall be suitable reinforced to prevent flutter.

o The air handling unit manufacturer shall provide all water piping internal to the unit that is necessary for multiple coil sections. This internal piping shall be connected so there is one inlet and one outlet coil connection for the air handling unit (See photos titled 12505B22R0003 – AHU-1 Repairs

– Pictures 3-22-22). The unit manufacturer/installer shall provide the necessary balancing devices in the piping to ensure the flow is apportioned correctly among the individual coil sections.

Contractor shall provide drain pans with drain pans of the following minimum specifications:

o Drain pans shall be provided that extends under the cooling coil, header and fan to provide satisfactory drainage with two outlet connections not less than 1-1/4 inch diameter located to ensure pan drainage.

o Additional Stainless Steel drip pans shall be provided at cooling coil sections that are more than one cooling coil high. These additional drip pans shall extend 2 inches beyond the coil casing on the air entering side and one third of the coil height but not less than 10 inches beyond the coil casing on the leaving side. The additional drip pans shall be provided with 1-1/4 diameter drains to the next lower drip or drain pans. Drain and drip pans shall be welded to the unit housing or coil casings and shall be fabricated from the same material as the housing. The main drain pan shall be insulated and shall be constructed of metal not lighter than 16 U.S.

Gage. Other drip pans shall be constructed of metal not lighter than 18 U.S. Gage.”

o Replacement coils shall conform to all current heat transfer and water use Federal Energy Management Guidelines for Energy Efficiency, heat transfer and water use.

Contractor shall provide Air Coils with the following minimum specifications:

o ANSI/ARI 410 – Forced-Circulation Air Cooling and Air Heating Coils.

o ANSI/NFPA 70 – National Electrical Code.

o SMACNA – HVAC Duct Construction Standards, Metal and Flexible.

Contractor shall provide the following document when project is completed:.

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Ames, IA March 23, 2022 o Submit shop drawings indicating coil and frame configurations, dimensions, materials, rows, connections, and rough-in dimensions o Submit manufacturer’s installation instructions.

o Submit manufacturer’s data showing that coil capacities, pressure drops, and selection procedures meet or exceed specified requirements.

During project work, contractor shall complete the following:

o Protect coil fins from crushing and bending by leaving in shipping cases until installation by leaving in shipping cases until installation, and by storing indoors.

o Protect coils from entry of dirt and debris with pipe caps or plugs.

CHILLED WATER COILS

A. Extended surface type with seamless copper tubes and continuous plate type aluminum fins.

B. Galvanized steel casing C. Maximum air velocity of 500 fpm D. Minimum water velocity in tubes of 3.2 fps (5/8” tubes), or 2.6 fps (1/2” tubes) at design flow. This is to prevent laminar flow at part load.

E. Turbulators are not permitted.

F. ARI rated with 0.0005 fouling factor.

G. Coils shall be sized based on Maximum Face Velocity FPM (500); Air Temperature (F) Entering DB 93, WB 78; Air Temperature (F) Leaving DB 51, WB 50; Capacity MBH 3175.3; Water Temperature (F) Entering 45, Leaving 57; GPM 483; Maximum Water PD (FT water) 23.6;

Maximum Air PD (FT Water) 1.75; CFM 30,105. These are listed as minimum requirements.

H. Maximum 144 fins per foot. No water carryover shall occur at design airflow and no anti-carryover coating shall be used.

I. Headers and pipe connectors shall be copper or brass for use in copper piping systems or cast iron with ferrous pipe connectors for use in steel piping systems. If header material does not match the piping material, use dielectric fittings at the change in material.

J. All duct coils shall be installed in watertight duct sections with drains per SMACNA Fig. 2-11. Coil sections shall have slip and drive connections and sufficient clearance for removal from ducts.

K. Coils shall have valved drain and vent connections at each row. Pitch slightly toward the drain connections. Coils shall be completely drainable.

Coils shall be cleanable by removing headers on the end opposite the connections.

L. Suitable for 200 psig operation.

M. Coils shall not have Turbulators.

N. Minimum 0.035” tube wall thickness O. Acceptable Manufacturers: Trane, York, Heatcraft, or McQuay, NAS

(Temtrol), or approved equal.

EXECUTION

INSTALLATION

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Ames, IA March 23, 2022

A. Install coils in accordance with manufacturer’s instructions. Pipe coils with air flow and water flow in opposite directions (counter flow).

B. Install in ducts and casing in accordance with SMACNA HVAC Duct Construction Standards, Metal and Flexible.

C. For custom air handling units, support coil section independent of piping on galvanized steel channel or double angle frames and secure to casing. Provide frames of maximum three coil sections.

Arrange supports to avoid piercing drain pans. Provide airtight seal between coil and duct or casing.

D. Protect coils to prevent damage to fins and flanges.

E. Make connections to coils with offsets and unions or flanges to allow coil to be removed without disturbing valves.

F. Provide drain pan and drain connections for all cooling coils.

Fabricate drain pan form 20 gauge stainless steel. Install a drain pan under each cooling coil per ASHRAE 62. Extend drain pans the entire width of each coil, including piping and header if in the air stream, and 2 inches from the upstream face of each coil to a distance of 1/3 the height of the coil (not less than 10 inches) downstream from the downstream face. Pitch drain pans in two directions towards the outlet, with a slope of at least 1/8” per foot.

Pipe drain pans individually to floor drain. Extend drain pan under header. Insulate all exterior surfaces of the drain pan in contact with the airstream with ½” elastomeric foam insulation with all seams sealed air tight.

G. Insulate headers located outside airflow as specified for piping.

H. Insulate U-bends located outside ducts or casings as specified for ductwork.

I. Comb all coils to repair bent fins.

3.0 Technical Requirements/Tasks: Technicians shall provide evidence of a minimum of 3 years of experience of coil replacement/welding.

4.0 Government Furnished: N/A

5.0 Work Hours: Government shall provide access during normal business hours

(Monday through Friday, 7:00 am to 4:30pm CST), excluding federal holidays.

6.0 Deliverables / Schedule:

Resume of Technician(s) Site Visit Report Chilled Water Coil Manufacturer’s Product Data Drain Pan Product Data Shop Drawings Operations and Maintenance Manuals

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Ames, IA March 23, 2022

7.0 Travel: N/A

8.0 Contractor’s Key Personnel: N/A

9.0 Security Requirements: N/A

10.0 Data Rights: N/A

11.0 Section 508 – Electronic and Information Technology Standards: N/A

11.0 Technical Point of Contact: Patrick Quance 515-203-1447

patrick.quance@usda.gov

12.0 Place of Performance: USDA-NLAE, 1015 N. University Bldg, Ames, IA 50011

Attachment: Air Handing Unit and Chilled Water Cooling Coil Schedules.

End SOW