Tetra Straw Factory Thermostat Report
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Transcript of Tetra Straw Factory Thermostat Report
Straw Factory P340-2220 Commercial Programmable Thermostat Report
Introduction
Complaints have been received recently from our employees working in the Straw
Factory at Tetra Pak Jeddah, stating the comfort cooling of the factory as
insufficient and the room temperature to be uncomfortable. However, a probe
into the Straw Factory later found out that everything from the Air Handling Units
to the chillers installed at the factory seemed to be working in order, instead two
of the thermostats installed in the room were not properly programed according
to needs.
Description of Equipment
There are a total of five P340-2220 Commercial Programmable Thermostats
installed inside the factory of which two were programed incorrectly. They
possess the following features:
A large, clear display with backlighting displays the following on its home
screen:
1. Current Temperature
2. Set Temperature
3. Time
4. Date
5. Period of use (Occupied/Unoccupied)
6. Fan Status
7. Cool Load / Heat Load
Menu Driven Programming
Ability to select multiple days
Precise temperature control
Multiple Override options
Outdoor Temperature Indications
Heating and Cooling Schedule
The thermostat installed in the Straw Factory is capable of controlling up to four
different schedules per day. Between each schedule there is a 15-minute interval
before the next schedule can be started. The four schedules are divided as
follows:
1. Occupied 1 – Denotes the time when workers arrive.
2. Unoccupied 1 – Denotes the time when workers leave.
3. Occupied 2 – Second occupied time.
4. Unoccupied 2 – Second unoccupied time.
Temperature Overrides
1. Hold Temperature
2. Override
3. Holiday
Status of our Equipment
After investigation we found two out of the total five thermostats to be faulty.
Their set temperatures were set at high values and schedule set as unoccupied.
Even the time, day of the week and the year had to be reconfigured, due to which
the system, which was operating on auto settings, had turned off the fan of that
area.
To rectify the issue new schedule periods and temperature set points were
devised such that the system would run continuously 24/7, except for the 15-
minute intervals between each schedule, and provides comfortable working
temperatures for the workers as well as the processes.
The following illustrations displays data from all the thermostats installed in the
factory:
The above illustration displays the data of thermostat 1 and 2
before and after it was reconfigured. The data confirms that
both of the thermostats were configured incorrectly.
The illustrations shows the data from thermostat 3,4 and 5
before and after it was reconfigured.
Note: The settings were edited for the days Saturday to Thursday.
Friday was selected as a holiday.
Settings Explained
Thermostat 1 and 2
Set Temperature: The set temperature of these thermostats was set as 85 F
previously, but the room temperature was already lower, due to which the
system had turned off.
Current Day: We conducted our investigation on Monday, but the current day on
these thermostats was set as Sunday.
System Status:
Heat – Thermostat controls the heating system
Off – Both heating and cooling systems are off
Cool – Thermostat controls the cooling system
Auto – Thermostat controls both the heating and cooling systems based on
temperature
Em Heat – Thermostat controls the auxiliary heat.
Fan Status:
ON – Fan runs continuously. Use this setting for improved air circulation or
for more efficiency central air cleaning.
AUTO – Fan is controlled by the system.
Note: When the thermostat is running the fan, the fan blade symbol appears next
to FAN to indicate the thermostat has the fan on.
Heating and Cooling Schedules:
1. Occupied 1 – Work arrival time.
This is set to start from 5:45am in the morning.
Cool Set Temperature: 72 F (Beyond this the system starts cooling)
Heat Set Temperature: 40 F (Below this the system starts heating)
2. Unoccupied 1 – Work exit time.
This is set to start from 6:45pm in the evening and last for only 15 minutes
before the next schedule initiates.
Cool Temperature: 77F
Heat Temperature: 40 F
3. Occupied 2 – Second occupied time.
This is set to start just after 15 minutes of occupied 1 period to
make sure to maintain a comfortable room temperature throughout the day.
Cool Temperature: 75F
Heat Temperature: 40F
4. Unoccupied 2 – Second unoccupied time.
This, like the first unoccupied time is set just for 15 minutes before next
schedule, occupied 1, starts again.
Cool Temperature: 77F
Heat Temperature: 40F
Temperature Overrides
Hold Temperature Until: Holds the temperature until the time set by the user, or
the next scheduled period time.
Override: Changes temperature setting until the next period starts.
Holiday: Changes the temperature setting for a designated number of days.
In this case Friday was selected to be a holiday.
The illustration shows the settings and data that is reconfigured for
the day Friday.
Fan Coil Units (FCUs)
Operation
The Fan Coil Units are used for cooling or heating the air in the room, depending
upon the operator’s requirement. They can be found in Offices, Hotel Rooms or
Shopping Centers, and their operation involves much similarity to the Air Handling
Units or AHUs which are installed in the cooling systems of large industries or
factories, however, unlike the AHUs that require extensive ductwork to deliver
cool air to the air condition space, chilled water is piped directly to the cooling
coils of the FCUs, eliminating the need for ductwork. Room air is drawn into the
FCU, where it is first passed through filters located at the out stream of the fan.
The filters are responsible for providing clean air and they do this by removing any
airborne contaminants that may have been present in the room’s air. The filtered
air is then transferred through the fan to the cooling coil, which basically cools the
air by transferring its heat to the chilled water, piped directly to the coil.
When there is a change in the room temperature, the room’s thermostat sends a
signal to the Automatic Control Valve attached to the pipe carrying chilled water,
the valve then regulates the amount of chilled water entering by opening or
closing according to the settings on the thermostat, to provide an adequate
amount of cooling to the circulating air of the room. Traditionally FCU contain
their own internal thermostat or can be wired to an external thermostat which
provides flexibility to the occupant to alter the Fan Speed, Set temperature,
Cooling mode to either cool or heat the room depending upon the season and it
even allows the occupant to feed in it different schedules according to his/her
routine.
Design
A fan coil unit may be concealed or exposed within the room or area that it
serves.
An exposed FCU may be wall-mounted or ceiling-mounted and includes a proper
enclosure to conceal the fan itself. It consists of a return air grille and a supply air
diffuser that is also set into that enclosure to distribute air.
Grille
Grille is an opening of several
slits side by side in a wall, usually
to allow the air to enter.
A concealed FCU may be installed within a ceiling void. The return air grille and
supply air diffuser, will be ducted to and from the fan coil unit and thus allows a
great degree of flexibility for locating the grilles to suit the ceiling layout.
Incorporation of a Building Management System to control FCUs
In most common modern buildings the control of the Fan Coil Unit is done
through a Building Management System (BMS). A BMS is a computer-based
system that is installed in the building for controlling, monitoring and optimizing
the building’s mechanical as well as electrical equipment such as HVAC systems,
lighting, security system, etc. Building Management Systems are critical
components to managing energy demand. Improperly installed BMS can cost up
to 20% of energy usage.
Diffuser
Diffusers are very common in
HVAC systems and they are used
in both all-air or air-water HVAC
systems. They are able to
distribute conditioning and
ventilation air evenly in all
directions while maintaining
minimum amount of noise.
At Tetra Pak Jeddah Building Management System is currently installed in and
controlling the Printer Zone, Laminator Zone, Slitter and Palletizing Zone, Straw
Chillers and Factory and Chiller Systems from 3 to 7 as depicted in the illustration
above.
This illustration shows how the Building Management System is monitoring the
Straw Factory area.
AHU1-DA1: Sensor controlling the damper that draws in fresh outside air.
AHU1-CV1: Sensor controlling the automatic valve that regulates the flow
of chilled water to enter the AHU.
AHU1: Sensor that controls the AHU’s fan speed.
AHU1-ST2: Sensor that shows the temperature of air that is being supplied.
AHU1-ST1: Sensor that shows the room temperature of the factory.
AHU1-SH1: Sensor that shows the humidity that is being drawn out from
the room.
AHU1-ST3: Sensor that shows the temperature of the air that is being
drawn out of the room.
AHU1-DA2: Sensor controlling the 2nd damper that allows the exhaust air to
circulate by mixing with the supply air.
Out-ST10: Sensor that shows outside temperature.
Out-SH10: Sensor that shows outside humidity.
This illustration shows how the Building Management System is installed in and
controlling the chiller system from 3 to 7.
Chiller Tank: Acts as a reservoir of water for the chiller to draw and release water.
CT-ST2: Sensor that shows the temperature of the hot water from where the chiller
draws in water.
CT-ST1: Sensor that shows the temperature of the cold water where the chiller
releases its chilled water.
CH7-P1A / CH7-P1B / CH-20(A – D): These sensors are installed on the pumps that
pump water from the tank towards the chiller.
CH (3 – 7)-ST1: Sensor that shows entering water temperature to the chiller.
CH-ST2 / CH7-ST2: Sensor that shows the leaving water temperature, once it has
been chilled, towards the tank.
AHU-SP1: Sensor that shows the pressure of water that is being pumped towards the
AHUs from the chiller tank.
AHU-ST1: Sensor that shows the temperature of water being pumped towards the
AHUs from the chiller tank.
AHU-ST2: Sensor that shows the temperature of water returned back to the chiller
tank’s hot area from the AHUs.
The incorporation of a Building Management System with the Fan Coil Units
could benefit the factory in a number of ways:
The Fan Coil Unit can become a local digital controller that will be
controlled and adjusted from a central point.
The BMS will eliminate the need for an external wired thermostat to be
installed which could get prone to unwanted alterations from occupants in
the room and take control of the internal thermostats in the FCUs.
Only the person in charge of the BMS will be able to control it as it would
require the user to log in before making any alterations to the system.
The BMS will display temperature readings of all the fan coil units:
a. Temperature reading of the supply from chiller
b. Temperature reading of the room
c. Temperature set point
d. Temperature reading of the return to the chiller
With all the temperature readings being displayed on a single central
location, anomalies in the system can easily be detected, unlike with
thermostats where each one needs to be configured separately by visiting
and observing them one by one.
The BMS will display the percentage of humidity:
a. Percentage of humidity in the air being supplied from the FCUs
b. Percentage of humidity in the air being drawn back to the FCUs from
the room.
With all the humidity readings being displayed on a single central location,
anomalies in the system can easily be detected.
Scheduling of all the thermostats will be done from central location
controlled by the Building Management System, instead of visiting each and
every thermostat in the factory to do the scheduling.
The BMS will be able to shut down and turn back the entire system on
again from a central location.