Brdg Docs 2800CW Mech Controls 012710.docx

2800 Cottage Way, Sacramento, CA Concept Design and Specifications Mechanical and Controls Upgrade Projects January 27, 2010

Mechanical and Controls Upgrade Projects Scope of Work and Concept Designs

Federal Building 2800 Cottage Way Sacramento, CA 95825

Prepared For:

General Services Administration

Mark Levi Buildings Services Branch 450 Golden Gate Ave. 4E 9PMFT San Francisco, CA 94102

Prepared By:

100 Montgomery

Suite 600

San Francisco, CA 94104-4331

(415) 974-0390

January 27, 2010 Copyright © 2010 GSA. All rights reserved.

BAS Re-commissioning Plan-Energy Evaluation Franchise Tax Building Phase I & II February 27, 2002 Commercial Office Building Energy Audit 120 Montgomery Street, San Francisco Pacific Gas & Electric Company August 29, 2003 For questions or comments pertaining to this report, contact Enovity Inc. Reproduction or distribution of the whole, or any part of the contents of, this document without permission of GSA is prohibited. Neither Enovity nor any of its employees makes any warranty, express or implied, or assumes any legal liability of responsibility for the accuracy, completeness, or usefulness of any data, information, method, product or process disclosed in this document, or represents that its use will not infringe any privately-owned rights, including but not limited to, patents, trademarks or copyrights.

© 2009 Enovity, Inc. All Rights Reserved 2 Preface

Site Information Federal Building: 2800 Cottage Way, Sacramento, CA 95825 Enovity Personnel This work was performed by the following Enovity team members:

Client Personnel The following personnel were involved in the audit work:

Table of Contents

BAS Re-commissioning Plan-Energy Evaluation Franchise Tax Building Phase I & II February 19, 2002

© 2010 Enovity, Inc. All Rights Reserved

© 2009 Enovity, Inc. All Rights Reserved Summary This document presents the scope of work and specifications for the mechanical and controls projects at the 2800 Cottage Way Federal Building, Sacramento, CA. There are three (3) sections presented in this document as follows:

Summary Building and System Descriptions Energy Project Scope of Work Project 12 : Install A Opacity And Temperature Sensor and VFD On Kitchen Exhaust Fan Project 13: Control System Upgrade Project 14: Energy Meters on All Major HVAC Equipment Project 15: Retrofit Chillers with VFDs Project 16: Retrofit Primary Chilled Water Pumps with VFDs Project 17: Retrofit Condenser Water Pumps with VFDs Project 18: Install Plate and Frame Heat Exchanger to Serve Computer Room Project 19: Demand Control Ventilation

Building and System Descriptions – 2800 Cottage Way This section provides a description of the building, lighting system, HVAC, controls and domestic water systems at 2800 Cottage Way, Sacramento CA.

Overview and Operation The 2800 Cottage Way Federal Building, located at 2800 Cottage Way in Sacramento, CA, was built in 1965 and was renovated and retrofitted from 1998 to 2000. The normal occupied hours for this building are 6:00 am to 6:00 pm, Monday through Friday.

The primary tenants of this building are the Bureau of Reclamation, the Bureau of Land Management, the Bureau of Indian Affairs, and the Fish and Wildlife Service. The equipment operating times are designed to ensure that comfort conditions are maintained in the building during normal working hours, after hours operation may be requested on an as-needed basis.

Building Envelope The facility is approximately 326,000 gross square feet. It has two floors above ground and no basement. There are two office wings that make up most of the total floor area, a single-story cafeteria building, and a utility wing.

Lighting Systems & Controls Interior lighting systems consist mainly of 1’ x 4’ recessed 13-cell parabolic fixtures with two F32T8/835 lamps and electronic ballasts. Interior lighting systems also include recessed canned, and 1’x1’ 4-cell parabolic fixtures which contain either two 13-watt, 18-watt or 26-watt 835 series 4-pin compact fluorescent lamps with electronic ballasts. The ancillary rooms are lit by 2-lamp 1’x4’ reflector strip T8 fixtures with F32T8/835 lamps and electronic ballasts. Zone manual single and dual switches control the interior lighting systems during normal office hours. The interior lighting are scheduled on or off through the Johnson Metasys front-end.

Exterior lighting consists of high wattage high-pressure sodium (HPS) controlled by photocells. A majority of the exit signs is LED type and consumes very little energy.

HVAC

Chillers & CHW pumps There are two 600-ton centrifugal chillers that provide chilled water for general space cooling and two 60-ton air-cooled reciprocating chillers for cooling the West Wing computer room. The main chillers are sized such that each one can meet the load at design conditions. The chiller design parameters are summarized in Table 2.4.1.

Table 2.4.1 – Chiller Design Parameters

The main chillers serve a primary/secondary chilled water distribution system. There are two 900-gpm constant-speed primary chilled water pumps, one for each chiller. The three secondary chilled water pumps (with VFDs) are piped in parallel to serve the building loads. These pumps draw CHW from the plant primary supply header (and/or bridge if necessary) and discharge it into the secondary CHW supply piping entering the building. The CHW loop then proceeds to the field loads, which have 2-way and 3-way coil valves at the air handlers. The primary and secondary chilled water pumps’ design parameters are summarized in Table 2.4.2.

Table 2.4.2 – CHW Pumps Design Parameters

Cooling Towers & CW pumps A single four-cell cooling tower provides condenser water for heat rejection for the main chillers. Each cell has a VFD-controlled propeller fan. Two cells are dedicated to each chiller. The cooling tower design parameters are summarized in Table 2.4.3.

Table 2.4.3 – Cooling Tower Design Parameters

Three condenser water (CW) pumps circulate water through the chillers and to the cooling tower. CWP-1 is dedicated to CH-1, CWP-2 is dedicated to CH-2, and CWP-3 serves as a backup to either pump. The cooling tower operating parameters are summarized in Table 2.4.4.

Table 2.4.4 – Condenser Water Pumps Operating Parameters

Boilers & HHW Pumps There are two water-tube boilers to provide heating hot water (HHW) and domestic hot water through a heat exchanger. The boilers’ operating parameters are summarized in Table 2.4.5.

Table 2.4.5 – HHW Boilers’ Operating Parameters

Six variable-volume hot water pumps provide hot water distribution throughout the building. The pumps’ parameters are summarized in Table 2.4.6, below.

Table 2.4.6 – HHW Pumps Operating Parameters

Air Handling Units There are twelve (12) main air handler units (AHUs). All air handlers are single duct variable volume AHUs and all have two-way cooling coil valves except for AHU-14, which has a three-way valve. The operating parameters are summarized in Table 2.4.7.

Table 2.4.7 – AHUs Operating Parameters

Control System The installed building automation system (BAS) is a Johnson Controls Metasys system which was installed during the major mechanical upgrade in 2000. The control system uses a multi-level BACnet or proprietary protocol control network. The primary network is a 10 Mbps Arcnet network referred to as the N1 Bus. The secondary control network uses a proprietary protocol and is referred to as the N2 network.

Energy Projects Scope OF Work – 2800 Cottage Way Project 12 : Install a Opacity and Temperature Sensor and VFD on Kitchen Exhaust Fan Scope of Work:

The existing kitchen hood exhaust fan KEF-1 serving the cafeteria is equipped with a constant speed 2-hp fan motor. This fan exhausts air out of the cafeteria at a rate of 3,200 CFM @ 2.5 in.WC. KEF-1 is turned on manually by the kitchen staff. The range exhaust hood is generally used Monday through Friday between the hours of 6:00 am and 3:00 pm. A variable air volume multi-zone air handler MZ-1 (Supply Fan - 8,500 CFM & Return Fan – 4,500 CFM, economizer section, heating and cooling coils) conditions the kitchen. The kitchen itself has a constant volume terminal with a re-heat coil providing about 1,800 CFM. An interlock with the hood forces the economizers to 100% outside air on MZ-1 when the kitchen exhaust air fan is running. This system set-up disables the ability to utilize the economizer properly and during hot or cold outdoor air temperature, conditions the heating/cooling loads are unnecessarily high when the kitchen exhaust hood is in use.

Slowing down the exhaust fan motor speed and reducing air flow from MZ-1 during periods when stove top is not in use will minimize the amount of exhaust and make-up air for the Cafeteria. Reducing the exhaust flow will allow the economizer to operate at lower outside air flows and decrease the cooling and heating load requirements during extreme hot and cold outdoor air temperatures.

This Contractor shall:

1. Provide variable frequency drive for the one (1) exhaust fan, KEF-1.

Install a new inverter rated motor for KEF-1.

Remove the existing fan motor starter from the bucket in the MCC and provide new wiring directly to the new VFD.

Existing disconnect shall be removed and replaced with new VFD which include disconnects and a manual bypass.

Provide for the VFD: BACnet card, by-pass switch and line reactor (see VFD specification); the VFD BACnet card shall be connected to the Johnson Metasys control system.

Provide a new kitchen hood control module to modulate the kitchen hood exhaust fan speed utilizing an infrared opacity sensor to determine the density of smoke and ramp the exhaust speed up when more smoke is present.

Disable the interlock between the kitchen exhaust and the economizer on MZ-1.

Provide a new VAV box with re-heat coil to serve the kitchen with pressure independent controls; control the VAV box and outside air damper on MZ-1 to provide sufficient make-up air to the kitchen.

Re-balance all registers connected to new VAV box.

Program new sequence of operation into the JCI Metasys system; Contractor shall provide a detailed sequence of operation during the design phase.

Provide updated graphics on the Johnson Metasys BAS showing new VAV box and all new control points.

Provide, at a minimum, the additional control points listed in Table 3.1.1.

Table 3.1.1 New Control Points

VFD

X

VFD

X

VFD

X

VFD

Virtual (Calculated from % speed)

KEF-1 Start/Stop

X

BAS

VAV Box Controller

VAV Box Controller

VAV Box Controller

X

VAV Box Controller

X

VAV Box Controller

BAS

X

Thermostat

Project 13: Control System Upgrade Scope of Work The existing control system is a Johnson Controls Metasys ARCnet (N1 Communications), this form of communications is difficult to support. The original Building Automation System (BAS) documentation is incomplete. A previous Facility Dynamics Retro-commissioning report identified and corrected controls problems with the HVAC equipment and calibration issues on temperatures and pressures sensors. Systems not included in the Facility Dynamics Retro-commissioning were VAV boxes and associated zones, computer room AC units, exhaust fans and smoke control and fire systems.

The existing fourteen (6) global controllers are Network Control Module (NCM) series, Peripheral Machine Interface (PMI) supervisory interface components that are of an older technology, some of which are experiencing communications problems and require a replacement to the newer Johnson Metasys Enhanced Architecture.

The overall objective of this upgrade is to replace all Metasys Controllers that control air handlers, chillers, cooling towers, boilers, pumps and exhaust fans with new BACnet MS/TP controllers; the new controllers shall be ‘FEC’ family of Metasys controllers and to replace the N1 bus and global controllers.

The Contractor shall implement a controls upgrade that shall include the following:

1. Demolition of Existing Materials and Equipment: All existing hardware that is replaced including computers and controllers shall be packaged and returned to the Government.

Supervisory Controllers: All existing six (6) Johnson Metasys NCM controllers shall be replaced with new Metasys Network Automation Engines (NAE) controllers with web based technology. New Control panels shall be provided to replace existing. The new controllers shall be able to communicate to both the existing N2 field controllers (without the need of additional Gateways) and the new BACnet NAE and FEC controllers.

System Level Controllers: All the existing system level controllers shall be replaced with the new BACnet Field Equipment Controllers (FECs). Existing control panels housing controllers shall be retrofitted to house new controller(s). All wiring (except where noted) and panel materials/devices shall be re-used. The existing system level controllers shall be replaced with new BACnet FECs on the following systems:

7– VAV single duct multiple zone Air handling Units (2 Supply Fans and Return Fan per AHU, actually labeled as AHU-1 thru AHU14 in Section 2 above) 1 – MZ-1 Air Handler and Air Handler AH-15 2 – Centrifugal Carrier Chillers 4 – 60-ton Air cooled chillers Roof, each with a 2-hp constant volume CHW pump 2 – Water tube boilers 4 – Cooling Towers with VFDs on Fans 2 – Constant Volume Primary CHW Pumps 3 – Variable Volume Secondary CHW Pumps 3 – Constant Volume Condenser Water Pumps 2 – Variable Volume Domestic Hot Water Pumps 4 – Variable Volume Heating Hot Water Pumps Zone Level Controllers: All zone level controllers shall remain and communicate/connect to new supervisory controllers (NAEs) using existing MSTP trunk. The new front end shall be able to fully communicate with every VAV box and every existing system or device that is currently on the BAS Network. All Analogue Output (AO), Binary Output (BO), Analogue Input (AI), Binary Input (BI) points for every VAV box, fan coil and other zone level systems shall be programmable from the new front end and the new front end shall be able to see every AO, AI, BO and BI point for every zone level system.

Fire Life Safety System: There is no interface with the Fire Control System.

Operator Workstation(s): A Metasys ADX server shall be supplied including software only; GSA will furnish Server. License shall include up to ten (10) additional workstations. The Metasys ‘Advanced Graphics’ package shall be installed and utilized as part of the ADX server. A new database to support both the existing N2 ‘zone level’ controllers and the new BACnet controllers shall be engineered and loaded into the new NAEs. All point object features and preferences used in the existing system shall be used in developing the new database. All existing Graphical pages shall be updated and converted for use in the new Metasys system extended architecture down to zone level.

Communications and Networking: New Ethernet (TCP/IP) Cat 6 cable shall be installed to support and connect the new NAEs. New MSTP trunk (to support BACnet over MSTP) shall be installed to connect the FECs to the new NAEs.

Sequence Programming: The contractor shall use the ‘Systems Operation Manual’ as a guideline for programming the sequences of operation into the new controllers. As part of the design phase contractor shall submit detailed sequences of operation for review. Contractor shall use optimized and energy efficient sequences of operation wherever possible. Examples include:

Supply Air Static Pressure Reset Based on Zone Level Feedback Supply Air Temperature Reset Based on Zone Level Feedback Condenser Water Temperature Reset Based on Wetbulb Temperature Chilled Water Supply Temperature Reset Based on Air Handler Cooling Coil Valve Position Differential Temperature Airside Economizer Control Optimum Start for Air Handlers.

Commissioning: The contractor shall fully commission the new control system according to the commissioning process outlined in the specifications.

Point to Point Verification: All existing points must be maintained as part of the controls upgrade. The contractor shall conduct a complete point to point verification of the system after the new system has been installed, including all AO, AI, BO and BI points as well as virtual points. The contractor shall use the points list provided as the reference to complete this point to point verification. For all the AI points the contractor shall conduct sensor accuracy verification and include the following in tabular format: the device tested, BAS value, reading from calibrated device, difference between BAS reading and calibrated meter reading, % difference, required % error from specifications and pass/fail result. The contractor shall present a report that includes the complete point to point check and sensor accuracy verification, and identify sensors that need to be replaced.

Points List: A complete points list shall be provided at the end of the job in a format as defined in the specifications.

Training: The contractor shall provide training as outlined in the specifications.

Design and Documentation: The contractor shall provide design documentation, submittals and ‘as built’ project documentation as outlined in the specifications.

Sequence of Work: The contractor shall submit a Construction and Installation Plan addressing all building systems to ensure that all equipment remains fully operational during construction and equipment change out. The Plan shall include details on how the contractor will switch over to the upgraded control system without interruption to HVAC systems during working hours (6.00 AM to 6.00 PM). System shall maintain building temperature, pressure and ventilation requirements during occupied hours (Monday thru Friday 6.00 AM to 6.00 PM) while controls upgrade is being implemented.

Project 14: Energy Meters for All Major HVAC Equipment Scope of Work Contractor shall;

1. Install electrical energy meters on the following equipment:

7 – VAV single duct multiple zone Air handling Units (2 Supply Fans and Return Fan per AHU) 2 – Supply and Return fans on MZ-1 and AH-15 2 – Centrifugal Carrier Chillers 4 – 60-ton Air cooled chillers Roof, each with a 2-hp constant volume CHW pump 4 – Cooling Towers Fans 2 – Primary CHW Pumps 3 – Secondary CHW Pumps 3 – Condenser Water Pumps 2 – Domestic Hot Water Pumps 4 – Heating Hot Water Pumps Install one (1) gas meter on the gas line to the boilers to measure gas use of the heating hot water boilers only:

Install BTU meters on the following equipment:

1. Secondary chilled water loop Condenser water loop to building chillers Hot water loop All energy meters shall interface with the Building Automation System.

All energy meters shall be on the new BACnet field bus.

A dedicated graphics shall be installed on the BAS for the energy meters and for calculated building load.

Virtual points shall be included for tracking the efficiency of the water side and air side systems

1. Actual virtual points shall be determined during the construction phase but contractor should assume a minimum of thirty (30) efficiency tracking virtual points. The specifications provide detailed requirements for the energy meters.

Project 15: Retrofit Chillers with VFDs Scope of Work The central cooling plant for this building consists of two Carrier 19XR water-cooled centrifugal chillers (each with a 600-ton cooling capacity) located in the 1st floor chiller mechanical room. Chilled water distribution consists of constant volume primary loop with two (2) constant speed pumps headered to serve the two chillers and a variable volume secondary loop with three (3) pumps on VFDs headered to serve the building’s cooling load.

The two chillers are constant speed. The inlet vanes of a centrifugal chiller provide capacity control, but the efficiency of such a chiller drops off quickly at the low end of the part-load range. Without speed reduction, the inlet vanes operate in the throttled position, thus reducing efficiency. With speed control, the compressor can slow down to match the head requirement without closing the inlet vanes. The addition of variable frequency drives will greatly improve the part-load efficiency of the chillers. Another benefit of a variable speed drive is soft start. The soft start feature prevents the starting inrush current from exceeding 100% FLA by applying power gradually. The soft start feature will result in increased motor and compressor life.

The contractor shall:

1. Provide, install and configure two Variable Frequency Drives (VFDs), for the two 600-ton Carrier XR chillers Ensure that at least one chiller (600-ton) is available at all times during construction Submit a revised sequence of operation during the design phase for staging the chillers and operating the central plant

1. Outline sequence;

If the lead chiller’s load is 70% (adj.) and rising for more than 15 minutes (adj.), then start-up the lag chiller.

When both lead and lag chillers are operating, operate both chillers at the same speed.

If both the lead and lag chiller are operating, and both VFD speeds are below 35% (adj.) and falling for more than 15 minutes (adj.) then shut-down the lag chiller.

Sequence of operation must take into account minimum flow requirements of the chiller.

Ensure that appropriate lock-out and tag-out be performed per OSHA guidelines during the retrofit process.

Remove existing starters, control panels and peripheral items.

Install Variable Frequency Drives and new chiller control panel per factory installation specifications and guidelines Fabricate and install VFD support mounts as required.

Fabricate and install service platforms as necessary to comply with NEC distance requirements.

Provide and install BACnet gateway between each chiller and the Johnson Metasys BAS; it shall be possible to control chilled water supply setpoint and chiller start/stop from the Johnson Metasys BAS; all chiller alarms shall be communicated to the Johnson BAS; all analogue points including refrigerant temperatures and pressures, oil temperature and pressure, chiller Amps, Volts and kW, chilled water and condenser water temperatures, DP across condenser and evaporator shall be communicated to the Johnson BAS.

Remove old Johnson Metasys controllers and integrate chillers as part of Johnson Metasys BACnet controls upgrade.

Provide all integration and programming of points to Johnson Metasys control system and update BAS chiller graphics. The additional control points that will be required but are not limited to the points list in Table 3.4.1.

Provide training plan and comprehensive onsite training.

Provide a fully functional and operational central chilled water plant. The chillers’ operation shall be comprehensively tested and commissioned; this shall include full functional testing of sequences of operation.

Figure 3.4.1 shows the chiller room plane with the existing chiller starters and proposed location of the new chiller VFDs. Figure 3.4.2 shows the chiller starters and existing Johnson controllers for the chillers.

Figure 3.4.1 Chiller Room Chiller 1 & Chiller 2 Starters to be replaced with new chiller VFDs

Figure 3.4.2 – Chiller Starters and Johnson Controllers

Project 16: CONVERT PRIMARY CHILLED WATER SYSTEM FROM CONSTANT FLOW TO VARIABLE FLOW Scope of Work:

The contractor shall;

1. Provide variable frequency drives for each of the two primary chilled water pumps; CHWP-1 (10-hp), and CHWP-2 (10-hp) Remove the existing pump motor starters from the buckets in the MCC and provide new wiring directly to the new VFDs. Figure 3.5.1 show the existing MCC and primary CHW pump buckets.

Existing disconnects shall be removed and replaced with new VFDs which include disconnects and a manual bypass; provide adequate support for mounting VFDs and disconnects.

The VFDs shall be mounted in the first floor mechanical room in close proximity to the respective pump served. The proposed location of the VFDs are shown in Figure 3.5.2 below.

Provide for each VFD: BACnet cards, by-pass switches and line reactors (see VFD specification); the VFD BACnet cards shall be connected to the Johnson Metasys control system.

Provide an insertion flow meter in the primary chilled water loop; the flow meter shall be installed on a straight length of chilled water return pipe on the primary loop in the sub-basement mechanical room; the flow meter AI point shall be tied into the Johnson Metasys control system.

Program new sequence of operation into the JCI Metasys system; Contractor shall provide a detailed sequence of operation during the design phase.

New primary CHW Differential Pressure sensors shall be installed on two (2) chillers; flow shall be calculated from DP.

The primary pump speed(s) shall modulate to maintain the same flow as the secondary system down to the minimum flow requirement for each of the chillers. A sequence of operation shall be written and programmed such that primary flow is properly balanced between chillers when more than one chiller is running.

A bridge is already in place so that minimum chilled water flow can be maintained through the chillers.

Provide, at a minimum, the additional control points listed in Table 3.5.1 on the Johnson Metasys BAS and update BAS graphics accordingly.

Perform thorough testing and commissioning; this shall include full functional testing of sequences of operation.

Figure 3.5.1 – MCC with Existing CHW Pump Buckets

Figure 3.5.2 – CHW Pump VFD Locations – Plan View Primary CHW Pump VFDs Proposed Location of New Primary CHW Pump VFDs

Table 3.5.1 New Control Points

x

DP Sensor

x

Virtual

x

DP Sensor

x

Virtual

VFD

VFD

x

VFD

x

VFD

x

VFD

x

VFD

x

Flow Meter

x

VFD (not required if Veris meter installed)

x

Veris Meter (not required if Veris meter installed)

Project 17: CONVERT PRIMARY CONDENSER WATER FROM CONSTANT FLOW TO VARIABLE FLOW

The contractor shall;

1. Provide variable frequency drives for the three (3) 40-hp primary condenser water pumps (CWP-1, CWP-2, CWP-3) Remove the existing pump motor starters from the buckets in the MCC and provide new wiring directly to the new VFDs. Figure 3.6.1 shows the existing MCC and primary CW pump buckets.

Existing disconnects shall be removed and replaced with new VFDs which include disconnects and a manual bypass; provide adequate support for mounting VFDs and disconnects.

The VFDs shall be frame mounted outside in NEMA 4 enclosure in close proximity to the respective pumps served. The proposed location of the three CW pump VFDs are shown in Figure 3.6.2 below. This location is not mandatory and shall be finalized during the design phase.

Provide and install for each VFD: BACnet cards, by-pass switches and line reactors (see VFD specification); the VFD BACnet cards shall be connected to the Johnson Metasys control system.

Provide an insertion flow meter in the condenser water loop; the flow meter shall be installed on a straight length of condenser water supply or return pipe in the sub-basement mechanical room; the flow meter AI point shall be tied into the Johnson Metasys control system.

Each condenser water pump speed minimum shall be set to maintain either the minimum flow requirement through the chiller condenser or the minimum flow requirement for the cooling tower (s), whichever is higher. When a chiller is running, and after minimum flow has been achieved, the condenser water pump speed shall modulate to maintain a condenser water Differential Temperature set-point (actual set-point to be determined during design phase) across the chiller condenser barrel.

Program new sequence of operation into the JCI Metasys system; Contractor shall provide a detailed sequence of operation during the design phase.

Provide full and comprehensive functional testing of new variable flow condenser water plant; this shall include full functional testing of sequences of operation.

Provide, at a minimum, the additional control points listed in Table 3.6.1 on the Johnson Metasys BAS and update BAS graphics accordingly.

Table 3.6.1 New Control Points

VFD

VFD

VFD

x

VFD

x

VFD

x

VFD

x

VFD

x

VFD

x

VFD

x

Flow Meter

x

VFD (not required if Veris meter installed)

x

VFD (not required if Veris meter installed)

x

VFD (not required if Veris meter installed)

Figure 3.6.1 – MCC with Existing CW Pump Buckets

Figure 3.6.2: CW Pump VFD Locations – Plan View

Existing P rimary C W Pump s

Proposed Location of New P rimary C W Pump VFDs

Project 18: Install plate and frame heat exchanger to serve computer room Scope of Work The computer room is served by two 30-Ton chilled water Computer Room AC units (CRACs). There are two 60-ton air-cooled chillers that serve the CRAC units; one Duty and one Standby. The CRAC units operate below their 30-ton capacity and the operating chiller is lightly loaded. A plate and frame heat exchanger (water side economizer) will be installed and operate to provide chilled water to the computer room AC units in lieu of the 60-ton air cooled chiller when outside air wet bulb conditions are such that the plate and frame heat exchanger can deliver cold enough chilled water.

The contractor shall:

1. Provide and install stainless steel plate and frame heat exchanger (HX) with LD channel plate arrangement on the existing 24-Hr server room chilled water loop and central plant condenser water loop; Figure 3.7.1 shows the proposed location of the new plate & frame heat exchanger (HX).

2. Size the plate and frame heat exchanger to meet a 30-ton load in the computer server room; Table 3.7.1 shows the minimum required design conditions for the new water side economizer.

3. Design the system so that additional plates can easily be added to the plate and frame heat exchanger should computer room loads increase in the future.

Table 3.7.1 Plate and Frame Heat Exchanger Minimum Design Conditions

4. Provide and install new differential pressure gauges on each of the two (2) inlets and two (2) outlets of the HX; tie points into BAS.

5. Provide and install new temperature sensors (x4, see points list) and tie-in to the BAS

6. Provide and install new inline chilled water pump.

7. Install plate and frame heat exchanger and new chilled water pump on concrete pad (s) in mechanical cooling tower yard as shown in Figure 3.7.1.

8. Provide and install all necessary new chilled water and condenser water piping, insulation, valves, actuators, BAS controls and programming necessary. Figure 3.7.2 shows the proposed single line diagram for the new plate and frame heat exchanger.

9. Seismically restrain all new chilled water and condenser water piping, as required to meet current code.

10. Add Johnson Metasys controllers as needed to monitor CHW valve position of the Liebert CRAC units.

11. A detailed sequence of operation shall be developed during the design phase; the design sequence shall incorporate the following;

a. Operate the plate and frame HE (water-side economizer) as the first stage of cooling when there is no demand for chilled water from other air handlers in the building, i.e at nights and weekends and during low outside air temperature conditions.

b. Operate one of the two (2) 60-ton air-cooled chillers (ACCH-1 or ACCH-2) as the second stage of cooling to serve the CRAC units when there is no call for cooling from other air handlers in the building and during low outside air temperature conditions.

c. When there is a call for cooling from other air handlers and the main central plant (CH-1 and CH-2) is enabled, the CRAC units shall also be served by the main central plant.

d. Vary CW Pump speed as required to maintain a chilled water supply setpoint off the plate and frame heat exchanger to the CRAC units.

e. Condenser water minimum temperature shall be 35 F when chillers CH-1 & CH2 are disabled.

f. Chilled water temperature reset

i. Implement a chilled water temperature reset based on air handler and CRAC unit CHW valve position.

12. Coordinate, with the building management, all work including, but not limited to shut-down, disassembly, reassembly, start-up, and testing.

13. Provide, at a minimum but not limited to, the control points listed in Table 3.7.2 on the Johnson Metasys BAS and include these points on BAS graphics.

14. Connect new pump and new starter to existing electrical distribution system per code. Verifying adequacy of service and connection location is a part of this work and shall not be excluded.

15. Provide comprehensive testing and commissioning of the plate and frame heat exchanger; this shall include full functional testing of sequences of operation.

Table 3.7.2 New Control Points

x

x

x

x

x

x

x

x

Figure 3.7.1 – Proposed 24-Hr Loop Water Side Economizer Location (circled)

Proposed New Water-Side Economizer and new CHWP Location

Figure 3.7.2 – Water-side Economizer Single Line Diagram

Project 19: Demand control ventilation

The contractor shall;

1. Install Carbon Dioxide (CO2) sensors in each conference room and training room, one (1) CO2 sensor per VAV box to be located on a wall at a height of 5 ft.

Provide, install and program demand control ventilation (DCV) system for a total of fifteen (15) rooms (conference rooms & training rooms)

a. The following is a list of rooms for which demand control ventilation shall be installed

i. Cafeteria Conference Room C1001

ii. Cafeteria Conference Room C1002

iii. Cafeteria Conference Room C1003

iv. East Wing Room 1602

v. East Wing Room 1805

vi. East Wing Room 1906

vii. East Wing Room 2904

viii. East Wing Room 2702-A

ix. East Wing Room 2619

x. East Wing Room 2802

xi. West Wing Room 1619

xii. West Wing Room 1620

xiii. West Wing Room 1931

xiv. West Wing Room 2617

xv. West Wing Room 2923 Install outdoor air CO2 sensor for reference.

Insure CO2 control sensors are factory calibrated (proof required) or field-calibrated with an accuracy of no less than 75 ppm.

The contractor shall replace the controllers on the VAV boxes that serve the conference rooms and training rooms where demand controlled ventilation will be implemented. The new controller shall have an additional analogue input for the CO2 sensor.

Program the VAV boxes and air handlers per the sequence of operation outlined below Based on ventilation codes, the ventilation rates must be the greater of either

1. The condition floor area times the applicable minimum ventilation rate (0.15 cfm per sq-ft)

1. For example, the minimum ventilation rate for every 1,000 sq-ft of conference room is 150 cfm using the area base method The maximum occupancy (square feet per person) of the space times the minimum ventilation rate of 15 cfm per person

1. For example, the maximum occupancy of a 1,000 square foot conference room is 67 people based on California Building Code rate of 15 square feet per person.

Using the occupancy based method the minimum ventilation rate is 1,005 cfm for every 1,000 sq-ft. Thus, the ventilation rate using the occupancy based method is 6.7 times higher than the area based method.

Sequence of Operation;

1. The demand control ventilation (DCV) will allow the system to reduce the amount of ventilation in response to measured level of CO2. The ventilation must be maintained to a level 600 ppm above the measured ambient level. As a result, the CO2 set-point the system must maintain shall be 1000 ppm.

The zone CO2 controls shall first increase the airflow rate at the space then increase the outdoor air rate at the air handler as described in the following sequence:

At the zone: during Occupied Mode, a proportional-only control loop shall maintain CO2 concentration at 1,000 ppm. The output of this loop (0 to 100%) shall be mapped as follows: The loop output from 0 to 50% shall reset the minimum airflow set-point to the zone from the design minimum up to the maximum cooling airflow set-point. The loop output from 50% to 100% will be used at the system level to reset outdoor air minimum.

At the air handler: The minimum outdoor air set-point shall be reset based on the highest zone CO2 loop signal from absolute minimum at 50% signal to design minimum at 100% signal. Design minimum is the sum of the code minimums as if there were no CO2 control.

Absolute minimum damper position for zones with CO2 controls is the greater of the following:

1. Title 24 value (e.g., 0.15 cfm/ft2) times the occupied area.

1. Or, 15 CFM per person times the design number of occupants.

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