20+ Senior Hvac Technician Interview Questions and Answers

Superheat is the temperature increase of a vapor above its boiling point at a given pressure.

• Superheat is important in HVAC systems to ensure proper refrigerant flow and system efficiency.

• It is calculated by subtracting the boiling point temperature of the refrigerant at a given pressure from the actual temperature of the refrigerant.

• The ideal superheat value varies depending on the type of refrigerant and the specific system, but typically falls between 5-20 degrees Fahrenhe...read more

To start the unit, the process involves checking the power supply, setting the thermostat, and turning on the unit.

• Check the power supply and ensure it is connected and functioning properly.

• Set the thermostat to the desired temperature.

• Turn on the unit and wait for it to start up.

• Monitor the unit to ensure it is running smoothly and efficiently.

Subcooling is the process of cooling a liquid refrigerant below its saturation temperature.

• Subcooling is achieved by removing heat from the refrigerant after it has been condensed.

• It ensures that the refrigerant is in a liquid state before it enters the expansion valve.

• The expansion valve reduces the pressure of the refrigerant and controls the flow rate into the evaporator.

• This causes the refrigerant to evaporate and absorb heat from the surrounding air or water.

• The expansio...read more

Increased head pressure in HVAC systems can be caused by various factors.

• Dirty condenser coils

• Blocked or restricted airflow

• Refrigerant overcharge

• Malfunctioning expansion valve

• Faulty compressor

• Ambient temperature increase

• Clogged filter drier

• Low refrigerant charge

• Kinked or blocked refrigerant lines

Chilled water circuit diagram includes components like chiller, pump, cooling tower, and air handling unit.

• Chiller: cools the water before circulating it through the system

• Pump: circulates the chilled water through the system

• Cooling tower: removes heat from the water before it returns to the chiller

• Air handling unit: distributes the chilled air throughout the building

Safety in HVAC systems is crucial to prevent accidents and ensure proper functioning.

• Safety features in HVAC systems include pressure relief valves to prevent overpressure, flame sensors to detect flames, and carbon monoxide detectors to monitor air quality.

• Regular maintenance and inspections are essential to ensure safety in HVAC systems.

• Proper training for technicians on handling HVAC equipment safely is important to prevent accidents.

• Following safety protocols and guidelin...read more

I work with various types of AC systems including split, window, central, and ductless.

• Split AC systems

• Window AC units

• Central AC systems

• Ductless mini-split AC systems

Water cooled chillers require proper water treatment and maintenance to ensure efficient operation and prevent corrosion and scale buildup.

• Water quality must be monitored and treated regularly to prevent corrosion and scale buildup

• Proper water flow and pressure must be maintained to ensure efficient heat transfer

• Regular maintenance of the chiller and its components is necessary to prevent breakdowns and ensure optimal performance

• Environmental factors such as temperature and h...read more

Superheat is the temperature of a refrigerant gas above its boiling point at a given pressure.

• Superheat is the amount of heat added to a refrigerant gas after it has fully vaporized.

• It is measured in degrees Fahrenheit or Celsius.

• Superheat is important to ensure proper refrigerant flow and prevent compressor damage.

• Too much superheat can cause poor cooling performance, while too little can cause liquid refrigerant to enter the compressor.

• Superheat can be adjusted by adjusting...read more

The refrigeration cycle is a process that removes heat from a space and transfers it to the external environment.

• The refrigeration cycle consists of four main components: compressor, condenser, expansion valve, and evaporator.

• The compressor is responsible for pressurizing the refrigerant gas, increasing its temperature and pressure.

• The condenser then removes heat from the refrigerant gas, causing it to condense into a liquid.

• The expansion valve regulates the flow of the liqui...read more

HVAC operation refers to the functioning of heating, ventilation, and air conditioning systems in a building.

• HVAC systems are responsible for regulating temperature, humidity, and air quality in a building.

• Heating systems can include boilers, furnaces, and heat pumps.

• Ventilation systems provide fresh air and remove stale air, and can include fans and ductwork.

• Air conditioning systems cool and dehumidify the air, and can include central air conditioning units and window units....read more

There are two main types of compressors: positive displacement compressors and dynamic compressors.

• Positive displacement compressors include reciprocating, rotary screw, and scroll compressors.

• Dynamic compressors include centrifugal and axial compressors.

• Each type of compressor has its own advantages and disadvantages based on the specific application.

• Positive displacement compressors are typically used for lower flow rates and higher pressures, while dynamic compressors are ...read more

The refrigeration cycle is a process in which a refrigerant absorbs heat from a low-temperature area and releases it in a high-temperature area.

• Refrigerant absorbs heat from the evaporator coil and evaporates into a gas

• The compressor then compresses the gas, raising its temperature and pressure

• The hot gas flows through the condenser coil, releasing heat and condensing back into a liquid

• The liquid refrigerant passes through the expansion valve, where it expands and cools down ...read more

Chiller inlet and outlet conditions refer to the temperature and pressure of the fluid entering and leaving the chiller.

• Inlet conditions include temperature, pressure, and flow rate of the fluid entering the chiller.

• Outlet conditions include temperature, pressure, and flow rate of the fluid leaving the chiller.

• Monitoring and adjusting these conditions is crucial for efficient chiller operation.

• Examples of inlet and outlet conditions include: 45°F inlet temperature, 60°F outle...read more

Refrigeration cycle is a process of removing heat from a low-temperature reservoir and transferring it to a high-temperature reservoir.

• The cycle consists of four main components: compressor, condenser, expansion valve, and evaporator.

• The refrigerant enters the compressor as a low-pressure gas and leaves as a high-pressure gas.

• The high-pressure gas then enters the condenser where it is cooled and condensed into a high-pressure liquid.

• The high-pressure liquid then passes throug...read more

AHU blowers conditions refer to the state of the air handling unit's fans.

• The condition of AHU blowers affects the airflow and temperature control of the HVAC system.

• Dirty or damaged blowers can cause reduced efficiency and increased energy consumption.

• Regular maintenance and cleaning of AHU blowers is important to ensure optimal performance.

• AHU blowers should be inspected for wear and tear, and replaced if necessary.

• Proper lubrication of AHU blowers can also improve their pe...read more

R.O plant working conditions refer to the environment and factors affecting the operation of a reverse osmosis plant.

• Temperature and humidity levels should be controlled to prevent damage to equipment

• Water quality should be monitored regularly to ensure optimal performance

• Proper ventilation is necessary to prevent buildup of harmful gases

• Maintenance and cleaning schedules should be followed to prevent contamination

• Safety protocols should be in place to prevent accidents and i...read more

The pH cycle withdrawing involves monitoring and adjusting the pH levels in a system to maintain optimal conditions.

• Monitor pH levels regularly to ensure they are within the desired range

• Adjust pH levels using appropriate chemicals or solutions

• Maintain accurate records of pH measurements and adjustments

• Ensure proper calibration of pH meters and probes

• Consult with water treatment specialists if needed for complex systems

Refrigerant has several advantages such as cooling, dehumidifying, and preserving food.

• Refrigerant is used in air conditioning and refrigeration systems to cool and dehumidify the air.

• It is also used in refrigeration systems to preserve food and other perishable items.

• Refrigerant is non-flammable and non-toxic, making it safe for use in homes and businesses.

• It is also environmentally friendly, as newer refrigerants have lower ozone depletion potential and global warming poten...read more

An open compressor has a motor that drives a piston to compress refrigerant gas, which is then released into the system.

• Open compressors are commonly used in large industrial refrigeration systems.

• They are less efficient than hermetic compressors, but are easier to maintain and repair.

• Open compressors require regular oil changes and inspections to ensure proper functioning.

• Examples of open compressors include reciprocating, screw, and scroll compressors.

EXV and TXV are types of expansion valves used in HVAC systems to regulate the flow of refrigerant.

• EXV stands for Electronic Expansion Valve and is controlled by an electronic signal.

• TXV stands for Thermostatic Expansion Valve and is controlled by temperature and pressure.

• Both valves regulate the flow of refrigerant into the evaporator coil to maintain proper temperature and pressure levels.

• EXV is more precise and efficient compared to TXV.

• Examples of HVAC systems using EXV a...read more

HVAC system work involves installing, maintaining, and repairing heating, ventilation, and air conditioning systems.

• Installing new HVAC systems in residential or commercial buildings

• Performing routine maintenance to ensure optimal performance

• Diagnosing and repairing issues with HVAC systems

• Replacing faulty components such as compressors or thermostats

• Ensuring compliance with safety and environmental regulations

• Providing excellent customer service and communication