WorksheetsUnit - 14 HVAC
Total questions: 18
Worksheet time: 9mins
Which refrigerant change in the condenser causes the refrigerant temperature to drop until it reaches the saturation temperature?
Condensing
Superheating
Subcooling
Desuperheating
Which change to the refrigerant in the condenser results in the largest rejection of heat?
Superheating
Desuperheating
Subcooling
Condensing
How does the airflow across a forced-draft condenser differ from the flow across an induced-draft condenser?
Airflow is pushed across the forced-draft condenser and is moved by convection across an induced-draft condenser
Airflow is pushed across the forced-draft condenser and pulled across an induced-draft condenser
Airflow is pulled across a forced-draft condenser and pushed across an induced-draft condenser
Airflow is moved by convection across a forced-draft condenser and is pulled across an induced-draft condenser
Where would you expect a remote air-cooled condenser to be located?
In the lower part of the cabinet that houses the refrigeration unit
In a location separate from all of the other refrigeration components
In a unit with the evaporator that is separate from the compressor
In a unit with the compressor that is separate from the blower coil
Why is low ambient control needed for buildings with excessive indoor heat loads and air-cooled condensers when outdoor temperatures are low?
To decrease the indoor heat load of the building to the point of the outdoor temperature
To increase the temperature of the ambient air surrounding the condenser
To maintain a minimum head pressure and ensure proper feeding of refrigerant to the evaporator
To adjust fixed-restriction-type metering devices to account for weather conditions
How are fan-cycling, fan speed, and damper low ambient control methods similar to one another?
They all reduce or restrict the amount of airflow over the condenser coil
They all cause a reduction in amp draw by blocking discharge from the fans
They all reduce the amount of current delivered to the fan motor
They all use a liquid receiver to back liquid refrigerant up into the condenser tubes
Which tools are most appropriate for removing light surface accumulation of dirt from a condenser?
Coil cleaning chemicals and personal safety gear
Stiff bristle brush and vacuum cleaner
Fin comb
Water and scrub brush
Nice work!
When would a fin comb be used to service an air-cooled condenser?
When the condenser is coated in a light accumulation of dirt
When more than 20% of the fins have been damaged
When the condenser is coated in heavy, greasy dirt
When 20% or less of the fins have been damaged
Which of the following describes the typical construction of a tube-in-tube water-cooled condenser?
A small tube that carries water is enclosed in a larger tube that carries refrigerant
Finned copper coil that carries refrigerant is enclosed in a welded steel compartment that contains water
A small tube that carries refrigerant is enclosed in a larger tube that carries water
Finned copper coil that carries water is enclosed in a welded steel compartment that contains refrigerant
Why is counterflow used in tube-in-tube condensers?
Why is counterflow used in tube-in-tube condensers?
To separate cooling tower water from condenser water
To prevent cross-contamination between refrigerant and water
To improve the corrosion resistance of the tubes
Which of the following BEST describes the relationship of biological growth to pH and scaling in a water-cooled condenser?
Biological growth raises the water pH, which leads to scaling
Biological growth lowers the water pH, which leads to scaling
Biological growth lowers the water pH, which helps prevent scaling
Biological growth raises the water pH, which helps prevent scaling
What is the purpose of blowdown in a cooling tower system?
To prevent the pH of the water from becoming alkaline
To reduce the temperature of the water
To prevent biological fouling of the water
To reduce the mineral concentration in the water
Which of the following will occur if the water sprays in an evaporative condenser are shut off?
The condenser will function as an air-cooled condenser
The condenser will overheat and be damaged
The condenser will automatically turn the water sprays back on
The condenser will shut off completely to prevent damage
What happens in an evaporative condenser when water is sprayed on the coil?
Heat from the refrigerant is transferred to the spray water, causing the refrigerant to evaporate
Heat from the spray water is transferred to the refrigerant, causing the refrigerant to condense
Heat from the spray water is transferred to the refrigerant, causing the refrigerant to evaporate
Heat from the refrigerant is transferred to the spray water, causing the refrigerant to condense
Which of the following would you see in a water-cooled condenser with low water flow?
Increased head pressure and decreased temperature difference across the condenser
Decreased head pressure and increased temperature difference across the condenser
Decreased head pressure and decreased temperature difference across the condenser
Increased head pressure and increased temperature difference across the condenser
What is the FIRST step in servicing a water-cooled condenser?
Draining the water mechanically
Circulating a chemical cleaning agent
Checking the water flow
Looking up the manufacturer’s specifications
How do you calculate the heat of rejection for an air-cooled condenser?
Multiply temperature change by gallons per minute by a factor of 1.08
Multiply temperature change by gallons per minute by a factor of 500
Multiply temperature change by airflow by a factor of 1.08
Multiply temperature change by airflow by a factor of 500
What is the purpose of a desuperheating coil added to the hot gas line of an air conditioner?
To power electric lights
To heat water
Maintain a miniumum head pressure
To run large refrigeration units
