HVAC interview questions


1.What is HVAC system?

Heating, Ventilation and Air Conditioning (HVAC) system work to maintain a controlled environment in a building.

2. What is VAV & CAV?

VAV: Variable Air Volume & CAV: Constant Air Volume.

3. What are the things we have in Indoor unit & Outdoor Unit

Indoor Unit: Evaporator Coils and Blower Fan

4. Which units consume power?

Compressor, Axial fan & Blower fan.

5. What is the local comfort cooling system/split air conditioning?

The local comforting cooling system has its evaporator is housed in a room unit and the condenser is housed in a separate outdoor unit. Both units are connected with the refrigerant flow and return pipes.

6. Difference between Axial and Centrifugal Fans

Axial Fan: Has the Parallel Movement of Air. Centrifugal Fan: Has the Perpendicular Movement of Air.

7. Name the different types of material used for duct fabrication.

GI Duct, Aluminium Sheet Metal, Fibre Glass Duct, Thick Black Mild Steel, Galvanized Steel Sheet & PUF.

8. What is cladding?

The cladding is a material used to coat structure interior, cladding be or cannot be waterproof, but it often controls how elements hit or fall on a surface.

9. What are the types of condensers?

There are three types of condensers:

  • Air-cooled: condenses refrigerant vapor by rejecting heat to ambient air blown over the finned condenser coil with the aid of a fan.

  • Water-cooled: condense refrigerant in the shell and on the outside of tubes through which water passes.

  • Evaporative: cooling tower, with the condenser tubes washed by the water spray.

10. How does vapour compression cycle work?

The Vapor-Compression Refrigeration Cycle is comprised of four steps.

Compression: The refrigerant enters the compressor as a low-pressure gas with low temperature. Then, the refrigerant is compressed adiabatically, so that the fluid leaves the compressor at high pressure and with a high temperature.

Condensation: High-pressure, high-temperature gas releases thermal energy and condenses within the “condenser” portion of the system. The condenser is in contact with the hot tank of the cooling system.

Throttling: The liquid refrigerant is pushed through a throttling valve, which causes it to expand. As a result, the refrigerant now has low pressure and lower temperature, while still in the liquid phase.

Evaporation: The low pressure, low temperature refrigerant enters the evaporator. The liquid absorbs heat from the cold reservoir and evaporates. The refrigerant leaves the evaporator as a gas at low temperature and low pressure, and re-enters the compressor, at the beginning of the cycle.