Meeting with Herb

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Meeting with Herb Steve2.20.03

• So guys, weve got a few questions

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Part One How it Works Now

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Major Changes from Original Plans

• Chiller removed
• Water Cooling Tower no longer used
• Rendered unnecessary once building was linked to
  chilled water system
• Deny Valve added to chilled water return
• Increased efficiency and decreased condensation
  at induction units
• Water enters 45 degrees F
• valve keeps water in system until it is 55
  degrees F

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Major Changes from Original Plans

• VFD (Variable Frequency Drives) added to air
  handlers
• Control based on static pressure in ducts
• Steam Humidifiers no longer in use
• General humidity in building neither controlled,
  nor tracked
• Exception the tenth floor
• Control System partially upgraded to DDC

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Part Two Basics and Definitions
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Basics

• AC 1 and AC 2 both two pipe systems
• Means only one set of coils for water
• 1 pipe in 1 pipe out 2 pipe
• Have to manually drain pipes twice a year to
  change over from hot water system to cold water
  system
• AC 1 handles the peripheral system
• Serves all the induction units
• Can release air at two different temperatures,
  one to north side of building, other to south

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Basics

• AC 2 serves core area
• Core defined as all areas not bordering wall of
  building, plus all of floors 1 and 15
• Only one outlet, thus no dual temp release
• Cant run heat and cooling simultaneously
• Can run 2 different release temperatures on AC 1
  and a third temp on AC 2

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Definitions

• Bridge Seasons
• Spring and Fall, when on the verge between full
  heating and full cooling
• Tough because only have two pipe system
• Used to have to manually play with the vents to
  capture night cool for coming day
• Summer Mode
• Program Steve wrote to blow out all air from
  building at night, sub-cool building for next day
• Possible area for improvement
• Economizer Mode
• Program that takes advantage of free cooling by
  using cool outside air when building air is
  hotter than outside air.

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Definitions

• End devices
• When Siemens system was added end devices
  (valves, etc.) remained the same
• PPCL (Powers Process Control Language)
• Language control program is written in
• Apparently a combination of Basic and Fortran

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Part Three Control System
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Control System

• Siemens DDC (Direct Digital Control)
• Three level system
• MLN (Management Level Network)
• Run over a server, 27 consoles on campus
• Herb has console in WJH, Steve has server
• Aside hacked into earlier this year!!
• Graphical interface on each console for ease of
  use
• BLN (Building Level Network)
• Actual network of wires and control panels in
  building
• Interfaces with computer program to actuate
  algorithm
• The main level that well be concerned with

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Control System

• FLC (Floor Level Control)
• Fairly simple control enter needed parameters
  into program and it manipulates a few valves to
  ensure parameters are satisfied
• 10th floor is only one in WJH really using this
  level of control
• ASIDE Steve knows Siemens systems quite well
• Would be willing to give presentation
• Can probably get Siemens mechanic to show us the
  physical connections in the building

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Analog vs. DDC (particularly thermostats)

• Difference in Heating and Cooling controls
• Cooling opens valve, increases water flow, thus
  lowers average temp of water in coils and cools
• Heating closes valve, water stays longer, more
  heat diffuses
• Analog stats cannot differentiate between
  heating and cooling seasons, so each season must
  have a seperate stat.
• Every time switch hot and cold water problems
  with occupants use dial the same way, get
  opposite effect
• DDC stats can be remotely programmed to account
  for seasonal change

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Analog vs. DDC (particularly thermostats)

• Analog Does not support remote control
• DDC stats can operate on programmed algorithms,
  or disabled completely.
• Analog devices do not provide data to the main
  control system
• DDC devices report input and output parameters to
  the main system. The DDC system cannot see
  analog devices
• More precise control is possible with DDC
• Dynamic valve positioning, digital precision

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Control Flow (Basement)
Intake
Filter Room
SF 1
Intake Plenum
To 19 duct (North Side) 28 duct (South Side).
Serves induction units.
Exhaust
Recirculated Plenum
Filter Room
SF 2
To 43 duct through central shaft. Serves core
system diffusers.
Return Air RF 1
Filter Rooms include A/C, Reheat, Humidifiers
Return Air from main shaft.
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Control Flow (Basement)
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Control Flow (Basement)

• Control Points
• Fan Speeds
• Modulate to maintain pressure setpoint as
  measured by sensors in supply and return ducts
• Damper positions
• Statically linked
• Opened or closed to maintain intake temp setpoint
• Uses outside air temp and return air temp as
  inputs
• summer mode and economizer mode turned on and
  off by outside air temp
• Summer mode controls nighttime building purges
• Economizer mode controls free cooling

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Control Flow (Basement)

• Control Points
• Hot water temp
• Linear function of outside air temp
• 0o gt 180o water, 30o gt 160o water
• Water flow to AC1/2
• Modulated to maintain Supply air setpoint
• AC2 supply setpoint
• Linear function of the average core temp measured
  in 1st floor lobby, 6th floor common room , and
  15th floor conference room
• AC1 setpoint is set manually

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Control Flow (Floor Level)

• Control Points
• Water flow to reheat boxes and induction units
• Controlled by local thermostats.
• Induction units provide heating in winter and
  cooling in summer.
• Reheat boxes provide heat in winter and nothing
  in summer.

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Heat Exchange

• Heats water in water circuit via heat exchangers
• AC1 and AC2 on separate loops. (hx1/2)
• HX 1 supports both hot and cold water
• Condenses (if steam)
• Leaves via return line
• Condensate metered (steam)
• Chilled water metered directly
• Never leaves basement as steam

In from steam tunnels
Control Pressure To heat exchangers
15psiltpressurelt25psi
5psiltpressurelt15psi
Pressure ingt25psi
1st Spence Valve
2nd Spence Valve
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Aside Domestic Hot Water

• Domestic refers to sinks, etc.
• Basically everything but heating system
• No longer on steam heat
• Used to be, but less efficient
• Produced by two gas boilers in basement

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Data Gathering/computer control

• DDC system has the ability to log data from all
  compatible devices
• DDC thermostats can log large numbers of
  subdatapoints
• User activity, temp logs, etc.
• Server has database of inputs and outputs
• Analog example temperature gt pressure on valve
• WJH only has DDC devices on 3 setpoint stats,
  10th floor, and some basement devices.
• All DDC devices can be remotely controlled by
  main system
• Disable user control
• Change setpoint functions for winter/summer

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10th Floor

• On completely separate system from rest of
  building
• Four pipe system
• Allows simultaneous heating and cooling
• Where winter cold water goes
• Uses two gas boilers for hot water
• Digital thermostats
• Occupant Adjustable thermostats in human spaces
• Humidity is controlled
• 100 fresh air

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Example 1 Graphical interface
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Example 2 Data Points
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Example 3 The Program
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Diversity in WJH Thermostats of All Flavors
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Other Miscellaneous Facts

• Condensate Return Lines
• Never installed
• To compensate, added deny valve which holds
  chilled water in, raising average release temp to
  55o, meaning less temp differential, less
  condensate
• Chilled water arrives at avg. temp of 45o
• Return Air
• Not ducted all the way to return shaft open
  plenum system
• Works fine unless holes in ceiling mess up flow,
  interior partitions prevent free flow to return
  intakes, etc.

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Metering Questions

• Electricity/Steam
• Accuracy of condensate meter
• Didnt get to this check notes from earlier or
  trip to chilled water plant
• Frequency of meter reading
• Once a month (?) double check
• Metering is done for building as a whole, no more
  specific data is available

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Part Four Usage
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Whos in WJH?

• How is the building being used?
• The following is off the top of Herbs head he
  has a day by day schedule of classes/sections and
  detailed floor plans if we need more info
• Also suggested we contact Bill Santaro at the
  Classrooms office 5-3801, after 1030am
• 14 classrooms 2 big auditoriums, 12 seminar
  rooms
• About four hundred people in offices

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What This Means for Control

• No individual control of rooms based on occupancy
• Heat assuming 100 occupancy
• This is done
• weekdays 7am-9pm
• Saturday 7am-6pm
• Sunday/holidays 7am-4pm
• Lighting
• Full schedule unclear
• Follows same general pattern as heating
• Exceptions lighting in stairs doubles 430-5pm
  (?)
• Guards responsible for turning off manual hallway
  lights

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Questions

• Metering
• How frequent?
• How accurate?
• Maintenance
• How often is system checked against independent
  measurements?
• History of leaks or other mechanical failure?
• Usage
• What exactly does it mean to heat for 100
  occupancy?
• What are the different settings for heat and
  lighting day vs. night?
• What is the exact schedule and means of switching
  lighting between day and night modes?
• When is Economizer Mode used?
• When is the system switched from hot to cold each
  year?

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More Questions

• Access
• We need to start taking data
• Security of data gathering devices
• Swipe Card or key access to basement
• Access to representative sampling of different
  rooms on both core and peripheral system
• Example need to measure heat loss between time
  air leaves handlers in basement and reaches
  different floors (help determine efficiency of
  air ducts in building struts)

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Even More Questions

• Access Continued
• Password access to Siemens system server?
• Other way we can observe system at work?
• Possible survey of WJH occupants

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Sources

• The preceding information was gathered by Keith
  Berkoben and Nathaniel Brooks during an interview
  with Herb Fuller (building manager of WJH) and
  Steve Robichaud conducted from 220-420pm,
  2/20/03.