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Questions and Answers
What is a characteristic of closed loop systems?
What is a characteristic of closed loop systems?
In closed loop systems, what can the heat exchange fluids be?
In closed loop systems, what can the heat exchange fluids be?
What is the purpose of a chiller in a closed loop system?
What is the purpose of a chiller in a closed loop system?
Which color represents the extent of the chilled water loop in Figure 1?
Which color represents the extent of the chilled water loop in Figure 1?
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What is the function of the closed loop heating system shown in Figure 2?
What is the function of the closed loop heating system shown in Figure 2?
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What is the common characteristic of closed loop systems regarding make-up water?
What is the common characteristic of closed loop systems regarding make-up water?
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What is the purpose of using freeze stats in chillers?
What is the purpose of using freeze stats in chillers?
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What is commonly used in refrigeration systems to prevent freeze-up?
What is commonly used in refrigeration systems to prevent freeze-up?
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Why are hot water closed-loop systems susceptible to scale formation and corrosion?
Why are hot water closed-loop systems susceptible to scale formation and corrosion?
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What can cause vestibule heaters to freeze up?
What can cause vestibule heaters to freeze up?
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What accelerates corrosion in closed loop systems?
What accelerates corrosion in closed loop systems?
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Why are air handling unit-heating coils susceptible to freezing?
Why are air handling unit-heating coils susceptible to freezing?
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Which inhibitor provides the best corrosion protection for systems of mixed metallurgy?
Which inhibitor provides the best corrosion protection for systems of mixed metallurgy?
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What is commonly used to fill heating systems for additional security against freezing?
What is commonly used to fill heating systems for additional security against freezing?
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What is the form of corrosion called when one particular metal is preferentially attacked in cooling systems?
What is the form of corrosion called when one particular metal is preferentially attacked in cooling systems?
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What risk is magnified in hot water heating systems as compared to chilled water systems?
What risk is magnified in hot water heating systems as compared to chilled water systems?
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How is solids fouling typically avoided in heat exchangers?
How is solids fouling typically avoided in heat exchangers?
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When does scaling become a risk in closed cooling systems?
When does scaling become a risk in closed cooling systems?
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What risk does freezing pose in closed loop systems?
What risk does freezing pose in closed loop systems?
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Study Notes
Closed Loop Systems Characteristics
- A characteristic of closed loop systems is that they recycle the same fluid repeatedly.
Heat Exchange Fluids
- In closed loop systems, the heat exchange fluids can be water, glycol, or brine.
Chiller Purpose
- The purpose of a chiller in a closed loop system is to cool the fluid.
Figure 1: Chilled Water Loop
- The color blue represents the extent of the chilled water loop in Figure 1.
Closed Loop Heating System
- The function of the closed loop heating system shown in Figure 2 is to provide heat.
Make-up Water
- A common characteristic of closed loop systems regarding make-up water is that they require minimal make-up water.
Freeze Stats
- The purpose of using freeze stats in chillers is to prevent freezing.
Refrigeration Systems
- Glycol is commonly used in refrigeration systems to prevent freeze-up.
Hot Water Closed-Loop Systems
- Hot water closed-loop systems are susceptible to scale formation and corrosion due to the high water temperature.
Vestibule Heaters
- Improper installation or inadequate air circulation can cause vestibule heaters to freeze up.
Corrosion
- Oxygen and high water temperature accelerate corrosion in closed loop systems.
Air Handling Unit-Heating Coils
- Air handling unit-heating coils are susceptible to freezing due to inadequate air circulation.
Corrosion Protection
- Molybdate-based inhibitors provide the best corrosion protection for systems of mixed metallurgy.
Freezing Protection
- Propylene glycol is commonly used to fill heating systems for additional security against freezing.
Form of Corrosion
- Selective corrosion is the form of corrosion where one particular metal is preferentially attacked in cooling systems.
Risk in Hot Water Heating Systems
- The risk of scaling is magnified in hot water heating systems as compared to chilled water systems.
Solids Fouling
- Solids fouling is typically avoided in heat exchangers by ensuring proper water treatment and filtration.
Scaling Risk
- Scaling becomes a risk in closed cooling systems when the water temperature is above 50°F (10°C).
Freezing Risk
- Freezing poses the risk of equipment damage and system failure in closed loop systems.
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Description
Learn about closed loop systems commonly used in heating, ventilation, and air conditioning (HVAC) systems. These systems recirculate a working heat transfer fluid, such as water, glycol solutions, or salt brines, and use minimal amounts of make-up water. The quiz covers the applications and characteristics of closed loop systems, including their association with chilled water-cooling systems, hot water heating systems, and internal combustion engine cooling systems.
