Chiller Systems: Routine Maintenance
In this module, we will take a look at an introduction to the routine maintenance of chiller systems.
Introduction
Recall that routine maintenance of a system is a regular check-up for a system.
Routine maintenance involves:
looking for common problems,
solving them, and
cleaning the HVAC system.
During maintenance, we need to ensure that:
the system is working correctly,
it is operating safely,
the fuel and electricity bills are efficient and optimal, and
the equipment has prolonged life
While going for any HVAC systems’ routine maintenance, we need to acquire permission to access the equipment. For safety precautions during chiller systems’ routine maintenance, we have to wear
helmet,
safety glasses,
gloves, and
safety boots
Recall that a chiller system is a machine that is used to produce cold water. It takes room temperature water and decreases the temperature. This cold water is used in industrial processes, as well as to cool buildings or industrial equipment.
Routine maintenance prolongs the life of the chiller and minimize the possibility of malfunctions. We carry out the chiller systems routine maintenance on
a time based schedule, or
a usage based schedule.
Time based routine maintenance is performed on chiller systems based on a calendar schedule. It is also called periodic maintenance. It is performed at fixed time intervals, regardless of chiller systems condition.
An example of time based routine maintenance is triggering maintenance on the first day of every month or once in a three-month period. It is scheduled in advance. So it is a planned maintenance. Usage-based preventive maintenance triggers a maintenance action when the usage hits a certain benchmark. This is also a planned maintenance.
An example of usage based routine maintenance is routine maintenance being scheduled on a motor bicycle every 1000km. This maintenance can be difficult to predict when the next future maintenance may be required.
Symptoms of some minor malfunction, which appear to be small or significant in the beginning, can grow into major defects in the course of time. It can result in costly and time consuming repairs. We should be very careful in detecting and taking timely action to prevent such minor defects from developing into major problems.
In chiller systems, the pressures, temperatures, current consumed, etc., can never be constant. These readings vary depending on the surrounding conditions and cooling load.
Chiller readings vary even during the course of a day itself. For example, as most offices follow a 9-5 timing, the cooling load would be high during this time. As employees would come into the building in the morning, the cooling load would suddenly increase due to frequent opening and closing of the doors in the building.
As long as the temperature inside the building is maintained within the desirable limit, we assume that the chiller system is working properly. But this is a wrong assumption because even a slightly inefficient chiller can maintain a desirable temperature if the cooling load is low. So we should be able to inspect and analyze the condition of the chiller system and take necessary action.
Lack of maintenance of chiller systems can reduce equipment capacity and efficiency. This forces the chiller systems to work harder, which results in increased power usage.
Chiller systems are one of the highest power consuming units in any building. Saving power is a big deal in chiller systems. So we have to perform chiller systems routine maintenance very carefully.
Routine maintenance of a system is a regular check-up for a system. Routine maintenance prolongs the life of the chiller and minimize the possibility of malfunctions. We carry out the chiller systems routine maintenance on
a time based schedule, or
a usage based schedule.
Chiller systems are the most power consuming units in any building. If they have any maintenance issues, they can consume even more power. Saving power is a big deal in chiller systems. So we have to perform chiller systems routine maintenance very carefully.
Visual Inspection
In this module, we will take a look at the visual inspection of the chiller systems. Skip to Quiz!
Introduction
Visual inspection is the oldest and most basic method of inspection. We inspect the equipment with our naked eyes. It does not require any special equipment for the inspection. We can detect scratches, dirt, foreign matter, and other appearance defects during visual inspection.
Visual inspection is more cost-effective compared to other methods. It is the easiest and most reliable inspection.
Visual inspection takes place with a technician walking around plants like the chiller system and visually inspecting every single part of it. A well-trained technician can detect most of the problems through visual inspection.
During visual inspection, we check for
Leaks,
Vibration,
Noise,
Tightness, and
Cleanliness.
Note that visual inspection is not limited to the above points only.
Leaks
If we find somewhere in the chiller system with water or oil traces, probably that is the leakage point. Some obvious places to look for leaks in the chiller systems are service valve caps, brazed fittings, and piping joints.
Vibration and Noise
Vibration and noise are usually addressed together because they are closely related. Noise is often a consequence of the vibration. Some technicians only focus on noise and use plenty of soundproofing. This is not the best approach since it does not solve the root cause.
Some vibration and noise are common even in a correctly installed and well-maintained chiller system. This is because the chiller system contains many moving parts. However, excessive vibration and noise can lead to other performance issues.
Recall that vibration is simply a back and forth movement or oscillation of components in motorized equipment. Eliminating vibration completely is not possible, but it can be reduced and isolated to a point where its effects are negligible.
The best way to control vibration is to prevent it with best installation practices. In the existing installations, it can be minimized with adequate routine maintenance. We install damping pads or spring mounts in chiller systems to reduce vibration.
We have to make sure that the vibration levels of the chiller system are maintained at a minimum. Ensuring the minimum vibration levels will improve the durability of the chiller.
In many cases, most of the noise is produced by the chiller components that are affected by propagated vibration. Noise tells how the chiller system is operating. Keeping noise levels to a minimum will help create an environment that is safer for people’s hearing.
Compressors are major source of noise in the chiller systems. They generate moderate to loud levels of noise depending on the
load of the chiller system, and
size and type of compressor used.
Centrifugal type of compressors is least noisy, followed by the reciprocating, scroll, and screw.
Condenser fans are the second major noise-generating component in the air-cooled chiller systems. This is because condenser fans move a lot of air. Water-cooled chillers of the same capacity as air-cooled chillers generate comparatively less noise because of the absence of condenser fans.
Tightness
We have to inspect all the electrical and mechanical connections to ensure they are secure and tight. This inspection includes all the electrical terminations and mechanical fittings. We need to tighten the connections if necessary.
All the bolts, nuts, and screws in the piping fittings should be tight in order to retain refrigerant or water in the chiller systems. We need check all the bolted connections with wrenches for tightness.
Cleanliness
We have to make sure that the chiller systems and the surroundings are clean. It is recommended that chiller systems to be cleaned if they are dirty. Regular cleaning will lower the operating costs and will also prolong the life of all the parts of the chiller systems.
Visual inspection is the oldest and most basic method of inspection. It is the easiest and most reliable inspection. A well trained technician can detect the most of the problems through visual inspection.
Compressor Maintenance
In this module, we will take a look at routine maintenance of the compressor in the chiller system.
Introduction
Recall that a compressor’s main job is to increase the pressure of a refrigerant. Compressors are the most energy consuming component in chiller systems. We will look at the routine maintenance of compressor of chiller systems.
Recall that earthing is the process of transferring unwanted electricity to the earth through a wire. We remain safe as all unwanted electricity is transferred to the earth. We give earthing to electrical systems to protect the system and the user from an electric shock.
We can find green and yellow earth wire that is connected to the metal casing of the compressor. The green and yellow wire is the earthing wire. We inspect the earthing of the system using a digital multimeter.
We have to place one of the leads on the copper tubing and the other on earth wire. If the electric system is connected to the earthing, it will show less resistance, or it will show infinite resistance. A good electric system should show a resistance value less than 0.5 ohms.
We have to check the resistance between each of the three terminals of the compressor, as shown in the video. As a rule of 3-phase motors, the resistance value between each of the three terminals should be the same.
Compressor oil in chiller systems is very clear and transparent. It keeps its color over a period of chiller system operation. Correctly designed and installed chiller system will operate without any problems. Generally, there is no need to replace the compressor oil even after 2 to 3 years of operation.
Compressor oil will become dark in color if it is exposed to
impurities, or
excessive temperatures on the discharge side of the compressor.
The quality of oil can also be degraded by the presence of moisture in the system.
When the compressor oil has changed color or degraded quality, it must be changed. Let us see a video to know how to replace the compressor oil in the chiller systems.
For changing compressor oil, we first turn off the power supply and shut off the exhaust and suction valves. We open the needle valve to release gas inside the compressor. We then open the oil discharge outlet screw to remove compressor oil inside the compressor. After removing all the oil, we tighten the oil discharge outlet screw.
By connecting the vacuum pump to the needle valve, we fill the oil from the oil can into the compressor until the oil mirror fills up. We open the exhaust and suction valves. After turning the power back on, we then check compressor working.
Oil analysis is a routine activity for monitoring oil health, oil contamination, and machine wear. The purpose of the oil analysis is to verify that the compressor is working according to the expectations. When an abnormal condition or parameter is identified through the oil analysis, immediate actions are taken to correct it.
Oil analysis is required on chillers to determine the condition of the compressor oil. We can also have an idea of the condition of the compressor from which the oil sample was taken. Through oil analysis, we can know that if any metal objects have contaminated in the chiller system.
Regularly scheduled analysis of the chiller’s compressor oil is a valuable aid in evaluating the internal compressor condition. Compressor oil holds valuable information about the chiller’s condition since it comes in contact with many important internal components.
Laboratory oil analysis can identify potential chiller problems so they can be resolved before creating issues. It can detect the presence of
harmful acids,
corrosion causing elements, and
abnormal metal wear particles.
The oil sent to compressor parts usually passes through the oil filter. This oil filter helps to trap the contaminants in the oil, which could damage the compressor. A clogged oil filter will prevent oil circulation in the compressor and must be changed. Let us see a video to learn how to replace the filter.
For changing compressor oil, we first turn off the power supply and close the inlet and outlet valves. We then remove the filter housing to remove old filter.
We replace the old filter with new filter and put the housing. We open the inlet and outlet valves. After turning the power back on, we then check compressor working.
As a rule of 3-phase motors, the resistance value between each of the three terminals should be the same. When the compressor oil has changed color or degraded quality, it must be changed. We have to change the clogged oil filter in the compressor.
Air-cooled Condenser Maintenance
In this module, we will take a look at routine maintenance of the condenser in the air-cooled chiller system. Skip to Quiz!
Introduction
Recall that a condenser’s main job is to cool down the refrigerant. Condition of condenser has a significant effect on the overall chiller system efficiency.
Non-maintained condenser may result in:
Compressor cycling on and off frequently,
Reduced cooling tonnage capacity,
Increased electrical power consumption, and
Chiller system has to work harder and run longer for the same set temperatures.
The two types of condensers in air-cooled chiller systems are:
Fin and tube condensers, and
Microchannel condensers.
Recall that fins are made of aluminum, and tubes are made of copper. The cleaning procedure for both the above condensers is the same.
Even a thin layer of dust on the condenser can act as insulation. It creates a barrier for the heat transfer from the condenser to the outdoor air, thereby reducing the efficiency of the condenser. This can result in a higher condenser discharge pressure. So condenser should be inspected periodically and cleaned thoroughly.
Before starting the cleaning, we first turn off the power supply to the chiller. We clean the top of the air-cooled chiller and condenser fans with water hose.
We then clean the condenser coils in the opposite direction to the airflow. We have to make sure that there is no debris on the condenser coils. Lastly, we have to clean the floor and the surroundings of the chiller.
Insufficient air supply over the condenser coils can increase the condenser discharge pressure. Insufficient air supply can be caused by
Damaged condenser fins,
Loose condenser fins, or
Restrictions to the airflow.
We have to straighten the condenser coil fins with a fin comb if they are bent. This process is similar to combing our hair. We should straighten the fins slowly. Else it may damage the coil.
Fins are always tightly attached to the copper tubes. When the fins get loose on the copper tubes, the condenser efficiency decreases substantially. This is because the condenser will not have sufficient surface area to transfer heat from the refrigerant to the outdoor air.
Something on the condenser like leaves and paper would restrict the airflow. This results in inefficiency by not rejecting the heat to the outdoor. Look if anything is blocking airflow through the condenser and remove it.
The two types of condensers in air-cooled chiller systems are:
Fin and tube condensers, and
Microchannel condensers.
Even a thin layer of dust on the condenser can act as insulation. So condenser should be inspected periodically and cleaned thoroughly.
Water-cooled Condenser Maintenance
In this module, we will take a look at routine maintenance of the shell and tube condenser in the water-cooled chiller systems. Skip to Quiz!
Introduction
Recall that a condenser’s main job is to cool down the refrigerant. Condition of condenser has a significant effect on the overall chiller system efficiency.
The type of condenser in water-cooled chiller system is:
Shell and tube condenser
Recall that shell and tube condensers consist of a series of copper tubes inside a larger shell. Water flows in the tubes, and hot refrigerant flows in the shell.
Scales form on the copper tubes due to the impurities in the water. We can see an example of scales in our daily life on our kitchen utensils. The whitish layers that form on any utensils are scales. Similar scales are seen on a chiller's condenser tubes.
Scales act as insulation for heat transfer, thereby reducing condenser efficiency. So we have to clean the condenser water tubes periodically.
For cleaning the water-cooled condenser, we first turn off the power supply and shut off the condenser inlet and outlet valves. Then we have to circulate the descaling chemical through the condenser with the help of a pump. Descaling chemical is a liquid used to remove scales from the metal surfaces.
We have to mix the proper amount of descaling chemicals and water in the chemical tank. More amount of chemical mixing can damage the copper tubes, and a low amount of chemical mixing may not be able to descale it properly. So the amount of descaling chemical mixing with water is a very important factor.
The external water pump circulates the descaling chemical through the condenser by increasing the pressure. The water pump circulates the descaling chemical from the chemical tank to the condenser and returns it back to the chemical tank.
The time of descaling chemical circulation through the condenser depends on the amount of scales. A higher quantity of scales requires a higher amount of descaling chemical circulation.
The more foam forms in the chemical can the more scales can be removed. We have to change the descaling chemical and water mixture if it becomes dirty during circulation.
After the circulation descaling chemical, we have to open the front side and back side covers of the condenser. Then we have to check whether the descaling chemical circulated through condenser tubes properly or not.
Due to descaling chemical circulation, the hardness of the scales reduces. We will clean the condenser with a tube cleaning brush attached to a steel rod. This process helps to clean the inside surface of copper tubes and clear all the blockages, scale, and dust properly.
After the brushing process, we have to flush the water from the condenser. Flushing is a very necessary process. This helps in getting out all the loosened scales.
Cooling Tower
Recall that the chiller’s shell and tube condenser is cooled with water from the cooling tower. For cooling the condenser effectively, the water supplied to the condenser should be kept as low as possible. For this, the cooling tower should be in good condition and of sufficient capacity.
Recall that cooling towers reduce water temperature by the evaporation process. As the evaporation process continues, scale forming minerals deposit in the basin. If the cooling tower is not cleaned, thick scales can form on the heat transfer areas and reduce cooling tower efficiency.
The main problems with the cooling tower are:
Corrosion,
Scaling, and
Microbiological growth, and
Fouling.
All these problems occur due to solids suspended in the air. Let us see a video to understand how these affect the cooling tower.
Corrosion reduces the lifespan of the cooling tower and may result in an unexpected breakdown. Scales reduce heat transfer efficiency. Microbiological growth reduces heat transfer, increases corrosion, and causes health problems.
Chemical dosing means adding chemical substances into the water. These chemicals used in the cooling tower can be used as a disinfectant to destroy the microorganisms and prevent recurring growth. These chemicals also reduce corrosion and scaling in the cooling tower.
Without proper chemical dosing, a cooling may lose its efficiency because of corrosion, scales deposition, and biofilm growth. To keep the cooling tower secure and productive, proper chemical dosing in the cooling tower is essential. Let us see a video to understand more about the chemical dosing process in the cooling towers.
Scales buildup on the fills reduces water flow through them. This causes a reduction in the amount of water evaporation, thereby reducing the cooling tower efficiency. Let us see a video to know how to clean the cooling tower.
Before starting the inspection, we first disconnect the power supply to the cooling tower. We then add cleaning chemicals to water in the basin of the cooling tower and mix them. We have to clean all components of the cooling tower like basin, nozzles, fills, etc.
Scales form on the copper tubes due to the impurities in the water. Descaling chemical is circulated through the condenser to remove scale from the metal surfaces. We will clean the condenser with a tube cleaning brush attached to a steel rod.
As the evaporation process continues in the cooling tower, scale forming minerals deposit in the basin. Chemical dosing means adding chemical substances into the water. To keep the cooling tower secure and productive, proper chemical dosing in the cooling tower is essential.
Evaporator Maintenance
In this module, we will take a look at routine maintenance of the evaporator in the chiller system. Skip to Quiz!
Introduction
Recall that chiller systems usually contain a shell and tube type of evaporator. Shell and tube evaporators consist of a bundle of copper tubes inside a large metal shell.
Chiller efficiency is greatly affected by the cleanliness of the evaporator tubes. Chiller efficiency declines rapidly if the evaporator tubes are not clean. After a period of time, the evaporator tubes become fouled with impurities picked up from the water system.
If evaporator maintenance is without correct methods and chemicals, it may damage the tubes. So, it is of most importance for the maintenance to be carried out by trained technicians.
We follow the same procedure as shell and tube condenser to clean shell and tube evaporator, but the frequency of cleaning is less. This is because some water evaporates in the cooling tower, so scale forming minerals density increases. In the evaporator, the same water circulates for a long time. There will be no loss of water.
Most chiller manufacturers recommend cleaning the condenser tubes annually since they are typically part of an open system. They recommend cleaning evaporators tubes once every three years since they are part of a closed system. Let us see a video to understand how to clean an evaporator with the rodding machine.
For cleaning the shell and tube evaporator, we first turn off the power supply and shut off the evaporator inlet and outlet valves. We have to remove the front and back covers of the evaporator. Then we have to clean the evaporator tubes with the rodding machine.
We also clean the gasket surfaces. We replace the gaskets if they are damaged. Finally, we reassemble the evaporator and check its working.
Chiller efficiency declines rapidly if the evaporator tubes are not clean. If evaporator maintenance is without correct methods and chemicals, it may damage the tubes. They recommend cleaning evaporators tubes once every three years since they are part of a closed system.
Water Distribution Components Maintenance
In this module, we will take a look at routine maintenance of water distribution components in the chiller systems. Skip to Quiz!
Introduction
Water pumps circulate cold water into a building. Centrifugal pumps are the most popular and commonly used for circulating water in chiller systems. Water pumps should be in good condition for the smooth running of chiller systems. Let us see a video about the maintenance of water pumps.
For performing the maintenance of the water pump, we first turn off the power supply. We check the stiffness of the water pump mountings. We have to tighten the nuts of the water pump if they are loose.
We check that all the electrical terminals of the water pump are tight. We have to check the pump and piping for leaks. We need to check for unusual vibration and excessive temperature during water pump maintenance.
When a centrifugal water pump overheats, it not only damages internal components but is also a hazard to technicians. It is important to ensure that pumps do not overheat.
We have to check the temperature of the pump with the hand by touching the outer casing. If it is overheated, we have to stop the pump immediately and let it cool. We need to rectify the problem before switching on the water pump.
Recall that vibration is simply a back and forth movement or oscillation of components in motorized equipment. Vibration in the water pump causes excessive noise. If we neglect vibration, it causes higher energy bills and even damage to the pump.
Major reasons for pump vibration are:
Damaged impeller,
Misalignment of shafts,
Water leakages, and
Weak foundation.
Let us look into how to resolve these problems of water pump vibration.
Recall that impeller is a component that rotates inside the casing of the centrifugal pump. Non-uniform wear or blade breakage of the impeller can increase the vibration in the pump. We have to replace the impeller if it is damaged.
We have to check the alignment of the pump with the motor. Misalignment of shafts is one of the key sources of vibration in centrifugal pumps. Let us see a video to know how to perform shaft alignment.
Water leakages in the centrifugal pump due to deterioration of mechanical seals. Excessive pressure, temperature, or corrosion can loosen the seals, which allows water to leak. A seal is a device that is used to control leakage between a rotating shaft and a water filled vessel.
We have to tighten the fasteners around the joint to fix a leaking pump. If the water leakage from the pump does not fix by tightening the fasteners, we have to replace the seals.
The purpose of the foundation for a centrifugal pump is to help dampen the vibration. The foundation of a centrifugal pump should be capable of absorbing the vibration transmitted to it without shifting the pump’s position. Check the hold-down bolts for tightness and tighten if necessary.
We have to ensure that the pump’s foundation is flat with a spirit level. We have to check the hold-down bolts for tightness and tighten them if necessary.
Recall that lubrication is the action of applying oil or grease to the motor to minimize friction and allow smooth movement. Lubrication is one of the main factors that impact the pump’s operation. By lubricating moving parts such as bearings, we can minimize the friction that causes wear and tear.
We have to clean all the outer parts of the centrifugal pump with a brush and wipe them with a cloth. We also need to clean the surroundings of the water pump.
Strainer
A strainer is a pipe fitting used to filter the water flowing through a pipeline. Strainers have wire mesh inside them that traps dirt from the water. These protect piping equipment from potential damage caused by the dirt.
A clogged strainer creates a barrier for the water flow through it. It also increases the load on the water pump, thereby increasing the energy consumption. So we have to clean the strainer for smooth operation. Let us see a video to know how to clean the strainer.
For cleaning the strainer, first, turn off the water pump and close the inlet and outlet valves. We remove the nuts of the strainer to remove the strainer cap. We then remove the mesh from the strainer and clean it with water. Finally, we have to reassemble the strainer and check for its proper working.
Valve
Recall that valves are a device used to decrease or stop the flow of a fluid. They’re a type of fitting that controls the flow inside the piping.
Some of the valves used in chiller systems are:
Ball valves,
Butterfly valves,
Gate valves,
Globe valves, and
Check valves.
Recall that lubrication is the action of applying oil or grease to the motor to minimize friction and allow smooth movement. Without lubrication, valve components wear out very fast. Lubricants reduce the friction between the moving parts of the valve. Let us see how to lubricate the ball valve with the grease gun.
For lubricating the ball valve, we have to connect the grease gun to the zerk fitting on the top of the ball valve. We then pump the grease by the handle of the grease gun, as shown in the video.
We have to inspect for the water leakage in the valves. If there is any leakage of water, we have to tighten the nuts of the valve. If the leak is because of the failure of valve parts, we have to change the valve.
For performing the maintenance of the water pump, we first turn off the power supply. We remove the mesh from the strainer and clean it with water. A grease gun is used to lubricate the valves. If there is any leakage of water, we have to tighten the nuts of the valve.
Question #1: Which of the following do we need to wear during the chiller systems routine maintenance?
Helmet
Gloves
Safety boots
All the above
Scroll down for the answer...
Answer: All the above
For safety precautions during chiller systems routine maintenance, we have to wear
helmet,
safety glasses,
gloves, and
safety boots.
Question #2: Which of the following maintenance is performed on chiller systems based on a calendar schedule?
Usage based maintenance
Refrigerant based maintenance
Time based maintenance
Brine based maintenance
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Answer: Time based maintenance
Time based routine maintenance is performed on chiller systems based on a calendar schedule.
Question #3: As long as the temperature inside the building is maintained within the desirable limit, we can say that the chiller system is working properly.
True
False
Scroll down for the answer...
Answer: False
It is a wrong assumption. Even a slightly inefficient chiller can maintain a desirable temperature if the cooling load is low.
Question #4: Which of the following would consume the highest power in a common commercial building?
Window ACs
Chiller systems
Automatic doors
Microwave ovens
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Answer: Chiller systems
Chiller systems are one of the highest power consuming units in a common commercial building.
Question #5: If chiller systems have any maintenance issues, they can consume _____ power.
zero
less
more
same
Scroll down for the answer...
Answer: more
If chiller systems have any maintenance issues, they can consume more power. So we have to do routine maintenance carefully.
Question #6: During the visual inspection, we inspect the equipment with ______.
Magnifier
Naked eyes
Multimeter
Thermometer
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Answer: Naked eyes
During the visual inspection, we inspect the equipment with naked eyes.
We are not required to use any special tool for visual inspection.
Question #7: Which of the following are obvious places to look for leaks in the chiller systems?
Piping fittings
Brazed fittings
Service valve caps
All the above
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Answer: All the above
Some obvious places to look for leaks in the chiller systems are service valve caps, brazed fittings, and piping joints.
Question #8: ______ is often a consequence of the _______ in the chiller systems.
Vibration; noise
Noise; vibration
Noise; refrigerant
Vibration; water
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Answer: Noise; vibration
Noise is often a consequence of the vibration in the chiller systems.
Question #9: Which of the following type of compressors is the least noisy comparatively?
Scroll
Reciprocating
Screw
Centrifugal
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Answer: Centrifugal
Centrifugal type of compressors is least noisy, followed by the reciprocating, scroll, and screw.
Question #10: Which of the following is the second major noise generating components in the air-cooled chiller systems?
Condenser fans
Cooling towers
Compressors
Metering device
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Answer: Condenser fans
Condenser fans are the second major noise generating component in the air-cooled chiller systems.
Question #11: Which of the following are used to check the tightness of the bolted connections?
Screwdrivers
Magnehelic gauges
Wrenches
Hammers
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Answer: Wrenches
Wrenches are used to check the tightness of the bolted connections.
Question #12: Regular cleaning will lower the ______ and will also increase the_______ of the chiller systems.
lifespan; operating costs
operating costs; lifespan
refrigerant amount; cooling
cooling; refrigerant amount
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Answer: operating costs; lifespan
Regular cleaning will lower the operating costs and will also increase the lifespan of the chiller systems.
Question #13: Which of the following wire transfers all the unwanted electricity to the earth?
Red
Black
Blue and yellow
Green and yellow
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Answer: Green and yellow
The green and yellow wire is the earthing wire. It transfers all the unwanted electricity to the earth.
Question #14: The resistance value between each terminal of the compressor should be ______.
same
different
infinite
zero
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Answer: same
The resistance value between each terminal of the compressor should be the same.
Question #15: We have to change the compressor oil when it becomes ________ in color.
dark
white
green
blue
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Answer: dark
We have to change the compressor oil when it becomes dark in color.
Question #16: Which of the following is monitored by oil analysis?
Oil condition
Oil contamination
Machine wear
All the above
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Answer: All the above
Oil analysis is a routine activity for monitoring
Oil health,
Oil contamination, and
Machine wear.
Question #17: Where is compressor oil analysis performed?
Hospital
Chiller plant
Data center
Laboratory
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Answer: Laboratory
Compressor oil analysis is performed at the laboratory.
Question #18: Which of the following prevents the circulation of oil in the compressor?
Dirty air filter
Clogged oil filter
Worn out impeller
Electric motor
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Answer: Clogged oil filter
A clogged oil filter prevents the circulation of oil in the compressor.
Question #19: Which of the following are the results of the non-maintained condenser? (Select all that apply)
Frequent compressor on and off
Reduced electricity consumption
Reduced cooling tonnage capacity
Increased cooling tonnage capacity
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Answer: Frequent compressor on and off
Reduced cooling tonnage capacity
Non-maintained condenser may result in:
Compressor cycling on and off frequently,
Reduced cooling tonnage capacity,
Increased electrical power consumption, and
Chiller system has to work harder and run longer for the same set temperatures.
Question #20: A thin layer of dust on the condenser _________ the chiller efficiency.
increases
decreases
does not affect
all the above
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Answer: decreases
A thin layer of dust on the condenser decreases the chiller efficiency.
Question #21: Which of the following might be the reasons for the insufficient air supply over condenser coils?
Damaged condenser fins
Loose condenser fins
Restrictions to the airflow
All of the above
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Answer: All of the above
Insufficient air supply over the condenser coils can be another reason for increased condenser discharge pressure.
It can be caused by
Damaged condenser fins,
Loose condenser fins, or
Restrictions to the airflow.
Question #22: _________ is a liquid used to remove scales from the metal surfaces.
Descaling chemical
Coil cleaner
Refrigerant
Ammonia
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Answer: Descaling chemical
Descaling chemical is a liquid used to remove scales from the metal surfaces.
Question #23: Which of the following reduces the hardness of the scales on the copper tubes in a shell and tube condenser?
Refrigerant
Hot water
Ammonia
Descaling chemical
Scroll down for the answer...
Answer: Descaling chemical
Descaling chemical reduces the hardness of the scales on the copper tubes in a shell and tube condenser.
Question #24: At the end of the descaling process, we have to flush the condenser tubes with _________.
Refrigerant
Water
Coil cleaner
Descaling chemical
Scroll down for the answer...
Answer: Water
At the end of the descaling process, we have to flush the condenser tubes with water.
Question #25: Which of the following components cleaning procedure is the same? (Select all that apply)
Chiller evaporator
Expansion valve
Microchannel condenser
Shell and tube condenser
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Answer: Chiller evaporator
Shell and tube condenser
We follow the same procedure as shell and tube condenser to clean shell and tube evaporator, but the frequency of cleaning is less.
Question #26: Which of the following two require frequent cleaning comparatively?
Shell and tube evaporator
Shell and tube condenser
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Answer: Shell and tube condenser
Shell and tube condenser requires frequent cleaning compared to shell and tube evaporator.
Question #27: A rodding machine is used to clean the ________.
Chiller’s metering device
Chiller’s evaporator tubes
Chiller’s evaporator fins
Chiller’s filter drier
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Answer: Chiller’s evaporator tubes
A rodding machine is used to clean the chiller’s evaporator tubes.
Question #28: Which of the following instrument is used to check the flatness of the ’s foundation?
Spirit level
Multimeter
Magnehelic gauge
Thermometer
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Answer: Spirit level
Spirit level is used to ensure that the flatness of the centrifugal pump’s foundation.
Question #29: Which of the following is the first action before starting the water pump maintenance?
We have to remove the water pump end cap
We have to turn off the power supply to the water pump
We have to check the tightness of the electrical terminals
We have to check the temperature of the water pump touching it
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Answer: We have to turn off the power supply to the water pump
For performing the maintenance of the water pump, we first turn off the power supply.
Question #30: Which of the following need to be done before cleaning the strainer? (Select all that apply)
We have to apply coil cleaner and wait for ten minutes
Water pump connected to the strainer should be switched off
Inlet and outlet valves of the strainer should be in closed condition
Water in the chilled water pipeline should be drained out
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Answer: Water pump connected to the strainer should be switched off
Inlet and outlet valves of the strainer should be in closed condition
For cleaning the strainer, first, turn off the water pump and close the inlet and outlet valves.
Question #31: Which of the following equipment is used to lubricate the valves?
Thermometer
Grease gun
Manifold gauge
Multimeter
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Answer: Grease gun
A grease gun is used to lubricate the valves.
Question #32: Which of the following action can stop the water leakage from the valve?
Applying grease
Tightening the nuts
Lowering chiller water temperature
Insulating the valve
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Answer: Tightening the nuts
We can stop the water leakage from the valve by tightening the valve nuts.