Chiller Startup Procedures: Chapter 2
Air-cooled Chiller Startup Procedures
After making sure that everything is fine during preliminary checks, a qualified technician begins with startup procedures. In this module, we’ll look at how to startup an air-cooled chiller. By the end of this module, you’ll be able to operate an air-cooled chiller. Skip to quiz!
Introduction
The process to start a petrol car and an electric car is not the same. Likewise, startup procedures for all the chillers are not the same. There can be slight variations in the process.
Different manufacturers may vary the components and design of a chiller. Chiller startup procedures may slightly differ depending on the manufacturer. It also depends on what type of chiller we are operating.
Recall that air-cooled chiller’s condenser is cooled by air. Air-cooled chillers use fans to blow outside air over their condenser. By this process, heat is removed from the refrigerant inside the condenser.
To startup a chiller, we first need to switch on the chilled water pumps. Switching on water pumps makes the water circulate through the chiller.
Chilled Water Pumps
Recall that water pumps circulate cold water into a building. Centrifugal pumps are the most popular and commonly used for circulating water in chiller systems.
Chilled water pumping includes two sets of pumps:
Primary pumps and
Secondary pumps.
The set of pumps that return water from a building to the chiller are called primary pumps. The other set of pumps that supply cold water from the chiller to a building are called secondary pumps.
To switch on water pumps, we need to press the ‘green’ button in the respective pump panel. For some water pumps, we just need to flip the switch to turn on them. Switching on water pumps depends on how they are connected to a power source.
After switching on chilled water pumps, we’ve to ensure that water is flowing through the evaporator. Water pressure in the pipes reveals whether the water flows through them or not.
Chiller Startup Procedure
After making sure that water is flowing through the chiller’s evaporator, an operator needs to turn on the power supply to the chiller. For that, the operator has to locate the chiller’s electrical panel and flip the main circuit breaker to the ON position.
After turning on the power supply to the chiller, the operator has to press the power button in the HMI of the chiller. It takes a few minutes to load the display of HMI.
An operator has to set the temperature and turn the chiller on in HMI. Operation procedures of mobile may vary depending on the operating systems like Android, iOS, Windows, etc. In the same way, operation procedures for chiller HMI may vary depending on the manufacturer.
Log Sheet
A chiller takes over half an hour time to stabilize all the parameters like temperatures, pressures, current, and others. So a technician should not take the readings immediately after switching on the chiller.
Taking readings in the log sheet allows the operator to analyze chiller performance by comparing it with previous readings.
Shutdown Procedure
If a technician switches off a chiller before switching off water pumps, water in the evaporator can freeze out. This happens when there is no running water through the chiller. Frozen water can even damage the chiller. So an operator has to follow the correct shutdown procedure.
For shutting down a chiller, an operator has to follow the reverse order of the chiller startup procedure. An operator has to first turn off the chiller at HMI and shut off the power supply at the electrical panel. After a few minutes, he has to switch off the chilled water pumps connected to the chiller.
After preliminary checks, an operator begins with chiller startup procedures. There can be a slight variation in the startup procedures for different chillers. A technician has to start chilled water pumps and then switch on a chiller.
Water-cooled Chiller Startup Procedures
You know how to start an air-cooled chiller. The startup procedure for a water-cooled chiller is very similar to an air-cooled chiller. As a water-cooled chiller consists of condenser pumps and a cooling tower, you need to focus on them as well. By the end of this module, you should be able to operate a water-cooled chiller. Skip to quiz!
Introduction
Recall that the water-cooled chiller’s condenser is cooled by water. The chiller’s shell and tube condenser is cooled with water. Cooling towers and condenser water pumps are used to supply water to cool the refrigerant inside the condenser.
Condenser Water Cycle
After preliminary checks, we’ve to start the condenser water cycle. Recall that the condenser water cycle consists of
Condenser water pumps, and
Cooling towers.
Recall that condenser water pumps are used to circulate from the cooling tower to the chiller’s condenser.
To start condenser water pumps, a chiller technician has to make sure that the suction and discharge valves are open. Then he has to press the ON button on the electrical panel of the water pumps.
The device used to cool hot water from the condenser is a cooling tower. Cooling towers are large boxes designed to remove heat from water by spraying it down through the tower.
To start cooling tower fans, a chiller technician has to press the ON in its electrical panel. He has to make sure that the cooling tower fans are rotating. Cooling tower fans do not rotate if the temperature of water in the basin is within specified limits.
The cooling tower fans only run when the temperature of water in the basin is more than the set point. So the fans cycle ON and OFF to maintain a water temperature of about 85°F.
Chilled Water Pumps
The chilled water cycle is the same for both air-cooled and water-cooled chillers. Water pumps are used to circulate water in this cycle. Chilled water pumping includes two sets of pumps:
Primary pumps and
Secondary pumps.
To switch on water pumps, we need to press the ‘green’ button in the respective pump panel. For some water pumps, we just need to flip the switch to turn on them. Switching on water pumps depends on how they are connected to a power source.
Chiller Startup Procedure
After making sure that water is flowing through the chiller’s evaporator and condenser, an operator needs to turn on the supply to the chiller and start it.
Chiller Shutdown Procedure
For shutting down the chiller, a chiller technician has to follow ‘Last in first out.’ He has to follow the reverse order of the startup procedure.
For shutting down the water-cooled chiller, a technician has to press the power button in the HMI and disconnect the power supply to the chiller. Then he has to turn off cooling tower fans and chilled water, and condenser water pumps.
BMS
In some plants, all the chiller components are connected with BMS. BMS stands for ‘Building Management Systems.’ BMS are computer-based control systems that monitor and control connected chiller components.
An operator can control all the chiller operations through BMS.
For a water-cooled chiller startup, a technician has to start
chilled water pumps,
condenser water pumps, and
cooling towers.
Next, he has to start the chiller by pressing the power button in HMI.
Question #1: Startup procedures for all the chillers are the same.
TRUE
FALSE
Scroll down for the answer...
Answer: FALSE
Startup procedures for chillers may vary from one chiller to other.
Question #2: Which of the following is the procedure to switch on chilled water pumps?
Pressing 'Green' button in electrical panel
Flipping the switch in the electrical panel
Turning on through BMS system
Depends on how water pumps are connected to a power source
Scroll down for the answer...
Answer: Depends on how water pumps are connected to a power source
Switching on water pumps depends on how they are connected to a power source. All the chilled water pumps do not follow the same procedure.
Question #3: In air-cooled chillers, an operator has to switch on condenser water pumps before switching on evaporator water pumps.
True
False
Scroll down for the answer...
Answer: False
This is false. Air-cooled chillers do not contain condenser water pumps.
Question #4: Arrange the following steps in a sequence to turn off a water-cooled chiller?
Switch off the cooling tower fans
Switch off the chilled water pumps
Shutdown the chiller
Switch off the condenser water pumps
Scroll down for the answer...
Sequence: 3, 2, 1, 4
1. Shutdown the chiller
2. Switch off the cooling tower fans
3. Switch off the condenser water pumps
4. Switch off the chilled water pumps
Question #5: A technician can control the operation of a chiller through a Building Management System.
True
False
Scroll down for the answer...
Answer: True
This is true. A technician can control the operation of a chiller through a Building Management System.