Chiller Replacement Summary and Intent.pdf

PROPERTY OF THE UNITED STATES GOVERNMENT

FOR OFFICIAL USE ONLY

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CHILLER REPLACEMENT PROJECT

Federal Office Building

705 N. Plaza, Carson City, NV

I. SUMMARY OF WORK

A. Scope of work: The work generally consists of replacing existing Chiller 1 located on the roof with a new air-cooled water chiller. The work is to provide a complete and workable chilled water system complying with the specific performance and design criteria indicated and all applicable codes.

1. Remove existing Carrier Chiller 1, Model 30GB090620.

2. Provide new complete Trane air-cooled water chiller with a minimum capacity of approximately 75.2 tons (264 KW).

3. Repipe chilled water supply and return piping and provide valves, fittings, thermometers, gauges, plugs and other appurtenances, as required to serve new Chiller 1.

4. Provide new automatic isolation valves for each chiller; one in the new piping for new Chiller 1 and one in the existing piping for existing Chiller 2.

5. Insulate and label piping.

6. Provide electrical service for new chiller.

7. Provide equipment and piping anchorage, structural support and seismic bracing.

8. Replace roofing in chiller mechanical well with new EPDM membrane roofing.

9. Demolition equipment, piping and appurtenances and remove demolished material from site.

10. Provide hoisting and rigging.

11. Provide patching and painting.

12. Start-up, test and commission the project work.

B. Owner Furnished Equipment and Services: The following equipment and services will be provided by the Owner:

1. New Alerton DDC controls for chilled water system.

2. Asbestos mitigation including testing, encapsulation, removal, treatment, and correction of existing asbestos-containing materials (ACM).

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II. DESIGN INTENT NARRATIVE

The intent of this project is to replace existing roof mounted Chiller 1 and install new chilled water system controls to provide an energy efficient chilled water production system and distribution system.

The basis of design to accomplish the project intent generally provides a new Trane air cooled water chiller. The new chiller will be selected to provide a minimum capacity of 75.2 tons (164 gpm at 45°F entering water temperature and 55°F leaving water temperature) with the outdoor ambient temperature at 105°F. Trane is the preferred manufacturer to provide consistent service requirements with existing Trane air cooled Chiller 2.

The project will include new isolation valves for each chiller. Each isolation valve will be controlled to open only when the associated chiller is running. Two existing chilled water pumps will remain as-is to pump through the chillers and distribute chilled water to the building loads. The existing condition has both chilled water pumps running continuously when the cooling system is operating which requires full flow through both chillers. This results in elevated chilled water supply temperature as unconditioned return water through the chiller that is off mixes with chilled water discharged from the operating chiller. The sequence of operation will be revised to operate the chiller isolation valves such that only one pump runs when one chiller is operating and both pumps run when both chillers are operating.

III. DESCRIPTION OF OPERATION

The chilled water system consists of two air cooled chillers and two pumps.

When the chilled water system is started, the chiller isolation valve on the lead chiller is opened, one chilled water pump is started and the lead chiller is allowed to start. When one chiller cannot maintain the chilled water supply temperature at set point, the second chiller isolation valve is opened, the second chilled water pump is started and the second chiller is enabled to operate.

The chilled water supply temperature is reset based on building load.

(Note: Description of Operation is provided for reference only. Controls are provided by the Owner.)

IV. SCOPE OF ENGINEERING SERVICES

Prepare construction documents for chiller replacement in two phases. The first phase will provide the design approach and equipment selection for use by the contractor in preparing a bid. The second phase will complete the construction documents to indicate the installation requirements for the replacement chiller.

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The design deliverables will include:

1. System design conditions.

2. Summary of Work.

3. Written Design Intent Narrative.

4. Equipment Selection.

5. Mechanical specification.

6. Roofing specification.

7. Verification of existing electrical service.

8. Verification of existing structural support.

Engineering services for construction support will also be provided, including submittal review and site observation.