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Exley Science Center – 265 Church St. – Data Center HVAC Replacement

Replace computer room air conditioning units, replace rooftop condensing units, install new economizer and pump package, install new drop ceiling and lighting, install hot and cold isle containment system. New system will replace a ~40-year-old system that is critical for the campus IT infrastructure.

  • Project Schedule: 5/28/19 – 10/1/2019

Our new data center upgrade summer-fall 2019. New LED lights, new ceiling. Because of virtualization we are reducing our cooling square footage. Using vinyl curtains we'll create a cold aisle (blue). Two new Liebert CRAC units (green) will discharge cold air above floor into this cold aisle. Two rows of 13 racks with servers will pull cold air and discharge into hot aisles (red). CRAC unit intake of hot air is from top. We are abandoning delivering cold air from below floor. (Raised floor only 7 inches high with all kinds of crap in there, cables, pipes, etc). Coolant gas will bypass chillers on roof if outdoor temp is 45 degrees or less generating significant savings (economizers). The rest of the room will be normal room temperature, we call this the L-Room (brown). Automatic control dampers will supply the L-Room with some cold air to maintain network equipment.

The HPCC is in the top row of racks on the left (room for 3 additional racks, light yellow dots, 5 existing racks, dark yellow dots).

Summary Bullets

⦁ Replace computer room air conditioning units (CRAC, Liebert DSE DA085)
⦁ Replace rooftop condensing units
⦁ Install new economizers and pump packages
⦁ Install new drop ceiling and lighting (LED) with dim switch
⦁ R-410A refrigerant, “free cooling” with ambient air 45 degrees or less (about 3,578 hours/yr or ~40% )
⦁ Reduce square footage for rack servers (L-Room normal room temperature), from 28×17 to 22×11 tiles, or ~50%
⦁ Install hot and cold isle containment system (vinyl curtains)
⦁ Abandon sub floor cold air delivery (push cold air above floor)
⦁ Total load of approx 88 Kw (~20% growth, 45 Kw for ITS, 25 Kw for HPCC)
⦁ Save approx 260,000 Kwh/yr of electricity (estimated at $35,000 /yr in savings)
⦁ ROI of 7-8 years

Vertiv Free Cooling Calculator 80 degree return air (conservative) with 70% load rates full free cooling hours are at 44% for Bridgeport and 48% for Hartford. So the expected 40% lsted aboveis low water mark as that percentage goes up if return air gets hotter. At 85 degree it yields between 53-56%.

Tech Summary

You don't get approval for a roughly $250K project without some serious reasons and numbers. To start with an air flow dynamics analysis, and attempted improvements, utterly failed to improve our data center's environment. With the help of FEACE we next embarked measuring our power consumption and cooling needs. The proposed solution is described above. The significant improvements are; abandon subfloor cold air delivery, reduce square footage cooled, free cooling below 45 degree ambient air, and much more energy efficient cooling units.

There are two sources of power and most racks (other than HPCC) are tied into both. Emergency power that comes from the enterprise UPS (with bypass to utility power and backed by gas generator) and plain utility power delivered directly from the power grid. The UPS logs kwh consumed. The utility panels were clamped for a month and consumption logged. The HPCC racks were individually logged using an PDU with amp meter. Since the HPCC is a big variable much effort was spend to assess it's consumption, read the HPC Power page.

Excley Data Center Loads total kW
Emergency power backed racks (x2) 43.5
HPC Racks 22 (Peak)
Storage (rstore) 2
GPU expansion 7
Sub Total 74.5 kW
Expansion Capacity - up to 25% of current load 18
Sub Total 92.5 kW
Lighting load and building envelope losses 2
Total Data Center Cooling Load 94.5 kW
Miscellaneous Load - UPS Lossess 5

The total cooling load for the data center space including load values above, and a potential for a 25% capacity increase is approximately – 94.5 kW. The 5 kW load associated with heat loss from the UPS is not factored into the data center cooing load and is planned to be handled separately.

It is recommended for the purpose of the study to use a total load of approximately 88kw, based on the capacity of the proposed cooling units. That would account for enough capacity to handle today's load and associated equipment losses with room to grow by approximately 18%. The cooling installed would also have the ability to be expandable if additional growth is required beyond the 88 kW design limit. The breakdown of the proposed load is as follows:

Proposed Excley Data Center Loads total kW
Emergency power backed racks (x2) 43.5
HPC Racks 22 (Peak)
Storage (rstore) 2
GPU expansion 7
Sub Total 74.5 kW
Expansion Capacity - up to 18% of current load 13
Sub Total 87.5 kW
Lighting load and building envelope losses 2
Total Data Center Cooling Load 89.5 kW
Miscellaneous Load - UPS Lossess 5

June Meetings


I will be updating you weekly on the progress in the data center. PP and vendors/contractors are meeting weekly (at 7:30am) to discuss past and upcoming week work items. Attached the preliminary schedule. End date Sept 30, hopefully.

Ceiling has been removed. Internal wall demolition to finish by Thu 6/27. ACC2 (roof chiller) removed, internal piping removed, new piping 70% complete for first new unit (we are running on two cooling units, set points lowered to 71 degrees). Very little dust, yea! CRAC2 (cooling tower in DC) to be demolished next.

Discovered non functioning humidifier, mobile wall track and steam/condensate piping end points behind ceiling. First two not expected, will be removed. Latter will be removed but may need a building wide shutdown of steam/condensate (planned for Tue 7/2 if no work around can be found). Will be announced.

Fire suppression system will be shutdown for modifications next week. Temporary fire/smoke system will be put in place. A floor tile vendor was found in case we need new ones.

June Photos

The high quality pictures in this batch are made by Physical Plant!

Before, L-room
Before, entire room
Before, CRAC1
General Contractor
L-Room, network area
5-6' wide cold aisle
New & old CRAC2, wall
CRAC2 chiller removed
Wall demolition
Wall gone, ceiling gone
Ceiling/Lights removed
Porch party lights up
Cool Shirts
KVM station
New CRAC at rigger
View from CRAC1
Cleaned ceiling
L-Room, UPS area

July Meetings


Rest of this week is devoted to removing old non-functioning, moldy, ductwork.
Old ductwork will be capped at door.
Continue refrigerant piping, electrical and insulation for CRAC2 unit.
CRAC units have arrived at rigger.
Next week new ceiling and lights will go up.
Fire suppression reconfiguration today.

Sidebar: Bill N. informs me Two L2 EV charges will be installed in L Lot of Lawn&Church serving 4 parking slots (like Freeman). Three L2 EV charges will be installed serving 6 parking slots this fall at Films Studio when construction fence is moved back.


Random safety inspections, all passed.
Duct demo complete.
Grid is going up (to hold new ceiling tiles)
Crac2 demo this week.
Roof units to arrive 7/31 (Excley loading dock closure, announcement will confirm)


Two ductless AC units installed on wall.
Ceiling grid 95% done.
Asbestos found in mastic on humidifier,
cut around seam and bag.
Rigger confirmed for 7/31 roof top delivery.
Excley parking lot D will be closed 7/31.
Second safety audit. Passed.
Dumpster abuse, different projects are using AZ's dumpster.


Old crac2 removed
New crac2 installed, planned startup Aug 14-16
Ductless AC piping ongoing
July 31st roof delivery, Lot D closure all work day
Consensus on cold air flow discharge (no changes)
Led lights being installed
Aug 12 containment measurements (vinyl curtain)


Crane arrives tomorrow, Thunderstorms expected
Excley lot closed 6am-5pm
Liebert missing components (gages, cables etc), resending
Equipment rails on roof ready
Ceiling work begun
Next week piping work for roof units
Aug 15th CRAC2 startup
Aug 16th modular wall up

July Photos

New plumbing and insulation
Related project, temp building UPS
Ductless wall AC units
Ceiling grid
CRAC2 platform
New floor tiles
Old CRAC2 follows exit sign
New CRAC2 arrival
New CRAC2 placed
New LED lights and ceiling pads
New piping, electric from roof
New piping for ductless AC units
Roof exchanger for ductless AC units
New CRAC2 unit innards
Roof equipment rails
CRAC2 cold air fans, surprise location.
Crane day 7/31, thunderstorms expected
Assembly of roof chiller units
Economizers (box) and chillers on stilts

Aug Meetings


New Liebert components arrived (lost items to be returned if found)
Roof delivery items secured in place
New CRAC1 unit piping started from roof downwards
New CRAC1 unit location moved one foot forward based on floor plan
Utility power interrupt coming (panel across pleone's door inside DC)
Announcement coming (need to make sure we have win/unix/dbs on floor)
New CRAC2 startup 8/16 followed by demo old CRAC1
Floor closure in front of new CRAC2 (relocate fans?)
Open more floor near old CRAC1 to get more cold air from old CRAC3
Room/Racks temp monitor log started anticipating room air flow changes




Meetings moved to Thu afternoon (1pm now vs 7:30am)
New CRAC2 unit on, data center temp dropped 5-7 degrees
Modular wall up
Fire suppressant install next, followed by ceiling
Old CRAC1 demolishing started


Wall AC units on
Dim switch relocated, network area missing led installed
Old CRAC1 removed
Floor tiles slowly reconfigure, monitor temps
Condenser leak in second unit, new item shipped
Deliver new CRACR1 before move in day
Fire suppression wiring and piping today

Aug Photos

Crane rooftop delivery
Drone rooftop side view
Drone rooftop top view
Odd location for dim switch
Novel use subfloor pedestal
Out of service foam fire suppressant
Do Not Operate, my life depends on it…
Transformer, new&old pipes, old mail tubes
Hot gas (left, arrives), cold liquid (right, returns)
Hot gas in, cooled to Liquifier (black)
From Liquifier to Economizer
Charging, R-410A gas only, zeotropic mixture
Seriously. Pink! Official industrial color
New Hall/Atwater-Excley generator (green one ;), 450 Kw, 16,000 lbs
08/16/2019 New CRAC2
08/19/2019, Temp dropped 5-7F
Modular wall up (back side)
Front, wall edges will connect with vinyl curtains)
Cold aisle looking at CRAC2
Old CRAC1 removed, new frame installed

Sept Meetings


New electrician but critical work coming up
Missing one track sensor
CARC1 installed, piping finish and leak test
New CRAC1 power up 9/19 by Liebert with owner training
Duct work and dampers install today



Sept Photos

5-6 feet cold aisle
Tour Guide on back of modular wall
New CRAC1 pressurizing
L-room return damper to hot aisle
1of2 L-Room cold air supply damper
10/19 Startup delayed
Cold aisle floor tile replacements
Old CRAC3 removed, 9/13/2019
Circulation pumps inside Economizer
New wall paint job. Thanks!
Zeocryte cylinder flock
Old and new fans
Vinyl doors and curtains, CRAC1 startup 10/10/2019
Top of racks vinyl curtain
CRAC2 vinyl curtain and door
West hot aisle return to CRAC units
U42 rack is 78 3/4“ tall, door is 79”

The End

Working with PP to see if we can do a floor tile cleaning.

Scroll up for the whole story backwards.

Commissioning happening 12/20/2019. Still to be fixed is the floor and the Ethernet cables knock outs.
Henk 2019/12/13 08:36


cluster/178.txt · Last modified: 2023/09/04 16:46 by hmeij07