Von Braun Center

Chilled Water System

Enhancements

AEE HUNTSVILLE CHAPTER MEETING JULY10, 2018

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Facility Facts

Original construction was completed in 1975.

The existing complex now totals approximately 483,000 ft2 and plans are underway for two more additions totaling approximately 150,000 ft2. This will bring the total under roof square footage to around 633,000 ft2.

HVAC systems currently includes four centrifugal chillers, two cooling towers, two(500HP), steam boilers and two (200HP) hot-water boilers supplying fifty-four various sized air handlers. Ice Rink operation is a separate 375 ton system.

The chilled water system contains approximately 36,000 gallons of treated water and is distributed throughout the complex by a secondary pump and various sized zone pumps.

There has been a total of four major renovation/additions in the facility’s history which has contributed unfavorably to the performance of all mechanical systems.

The VBC’s current annual utility budget: $1,365,000.

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Project Objectives

Determine system inefficiencies: This includes flow control, water supply temperature, supply and return delta temperatures (ΔT),

capacity losses or the inability to deliver available capacity to all

zones throughout the entire chilled water system.

Provide recommendations for inefficiencies: These

recommendations were based on enhancing overall system

performance, increased energy efficiency, simple payback ROI; as

well as consequences of cost for the organization if the

recommendations were not executed.

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Existing Chilled Water

System Operation

Chilled water is produced from two separate locations: South Hall

(built in1996) produces1,350 tons and North Hall (built in1986),

supplies 400 tons. Combined total capacity is1,750 tons.

Zone distribution pumps are located in the Arena boiler plant(built

in1975), South Hall chiller plant (built in1996), and North Hall chiller

plant (built in1986).

Chilled water is distributed to the complex’s various sized air handlers (Total of 54) from three separate areas at a constant

volume.

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Site Observations and Inefficiencies

Majority of the air handlers tested recorded low return water

temperatures.

Several cooling coil’s balancing devices are inoperative, thus

chilled water flow to the coils can not be adjusted and therefore;

overall system balance is unachieved.

A section of chilled water piping (Arena South Concourse)was

found to be installed incorrectly causing warm return water to be

introduced to the supply water.

South Hall decoupler and piping arrangements were allowing

massive bypass of return chilled water back to the supply chilled water.

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Site Observations and Inefficiencies

Distribution zone pumps are constant volume and all are piped in

series back to the chillers in the South Hall plant.

All pumps are delivering maximum flow causing unnecessary pumping

power and chilled water generation that exceeds what would be

required to meet actual load.

Lack of circuit setters or functioning 3-way control valves at older

handlers

This results in maximum chilled water flow regardless of demand needed

at the air handler which exacerbates the system’s already low ΔT

syndrome.

The entire chilled water system was completely out of balance.

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Recommendations

1. Chiller/Pump Replacement. Cooling Tower Refurbishment

2. South Hall Decoupler Removal/Piping Modification

3. Replace Air Handler 3-Way Control Valves and Zone Distribution Pumps and Controls

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Recommendation #1

Chiller/Pump Replacement

Simplify overall operation and centralize chilled water production to the South Hall chiller plant.

Replacement of existing South Hall chillers CH-5, CH-6, and remove North Hall chiller CH-3.

Decommission and remove two of the three existing chillers in the South Hall a 300 ton and 450 ton machine along with corresponding primary pumps.

Decommission and remove the existing 400 ton North Hall chiller along with its corresponding primary pump and the North Hall transfer pump.

This removes a total of 1,150 tons of existing chiller capacity.

Existing equipment to remain will be one 600 ton chiller located in the South Hall and the existing North Hall plate and frame water-side economizer heat exchanger.

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Recommendation #1

Chiller/Pump Replacement

Install two 600 ton water cooled centrifugal chillers with VFDs and

free cooling water-side economizers along with new primary pumps.

Install new condenser water pumps and VFDs to serve each new

chiller.

Install new redundant secondary chilled water transfer pump and

VFD in parallel with the existing pump.

With a total of 1,200 tons of chiller capacity added back to the

plant; the chiller plant is now capable of providing 1,800 tons of

chilled water to the complex.

Refurbish the existing 2,944 ton cooling tower.

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Recommendation #1

Chiller/Pump Replacement

All new equipment will incorporate VFDs and electronic controls to

sequence chillers to obtain maximize efficiency while reducing

electrical peak demand.

Staging of the three chillers will be automated; based on chilled

water demand instead of manual operation.

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Recommendation #2

South Hall Decoupler/Piping Modification

Remove the existing decoupler, pipe, and associated valves.

Re-configure the chilled water supply and return piping serving all

three chillers to tie-in downstream of the new return loop; prior to the

air separator and the first distribution pump branch take-off.

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Recommendation #3

Replace Air Handlers Control Valves, Zone

Distribution Pumps, and Controls

Removal of existing air handlers chilled water 3-way control valves

and replace with 2-way pressure independent control valves.

Install new zone supply pipe temperature sensors and flow meters.

Replacement of each zone distribution pump with variable speed

drive pumps with remote differential pressure control.

Installation of a new 10” chilled water supply header associated

with zone pumps A,B,C, and D&E to create a common supply in the event of a loss of any of the connected zone pumps.

Replace the Arena to North Hall secondary transfer pump with a

new variable speed drive pump.

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Project Cost Summary

Recommendations 1-3: Estimated Installed Cost-$2,885,283

Estimated Yearly Savings: $303,075

Simple Payback ROI: 9.52 years

Total Life Cycle Savings: $3,176,216

Note: Total savings are achieved only when all recommendations

are combined together in a comprehensive chilled water

optimization project. The individual projects are not inclusive of

each other.

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Project Phasing Plan

Year 1: South Hall Chiller Removal/Replacement along with Decoupler/Piping modifications. Install new transfer pump with VFD. Refurbish the South Hall cooling tower. COMPLETED 3/18

Year 2: Arena “D&E” pump/VFD, main header installed, control valves replaced with re-balance. Concert Hall “B” pump/VFD, control valves replaced and re-balance. CURRENTLY IN DESIGN PHASE

Year 3: East Hall “C” pump/VFD, control valves replaced with re-balance. East Hall 3 “C-2” pump/VFD, control valves replaced, and re-balance.

Year 4: North Hall Chiller removal with new zone pump/VFD and transfer pump/VFD install, control valves replaced, controls, and re-balance.

Year 5: Admin/Playhouse “A” pump/VFD, control valves replaced, controls with re-balance. South Hall Valves replaced, controls, and re-balance.

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Summary Three target areas of improvements required in order for the chilled

water system to operate correctly and efficiently. Projects were prioritized and phased to minimize interruptions.

A large portion of the first-cost expenditures (82%) was identified in

the Von Braun Center’s existing five year CAPEX plan,

Considerable benefit will be realized when all phases are completed

i.e. energy savings, reduced labor associated with

repairing/maintaining the cooling systems; hence, the ability to

reallocate labor within the facility, and better control of space

environmental conditions. Also, many end-of-life components will be

replaced as a part of this project.

TVA energy rebates were available for the first phase of the overall

project. The VBC received $35,728.00 from TVA for phase I.

The existing two chillers that were removed was sold for salvage for

the amount of $11,700.00.

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Thank you Trane Building Services for

partnering with the Von Braun

Center to make the first phase

a complete success.

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Questions

and

Comments?

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