#HVAC Interview Question:- 11) What is constant volume system?

Constant air volume (CAV) is a type of HVAC system.

In simple CAV system, the supply air flow rate is constant, but the supply air temperature varied to meet the thermal loads of a space. Most CAV systems are small and serve a single thermal zone.

#HVAC Interview Question:- 12) What is Refrigerant?

Refrigerant is a substance or mixture usually a fluid used in heat pump & refrigeration cycle. In most cycle it undergoes phase transitions from a liquid to gas and back again.

It is used for transfer the heat from one place to another place in refrigeration cycle.

#HVAC Interview Question:- 13) What is BTU?

The British thermal unit (BTU) is a tradition unit of Heat.

It is defined as the amount of heat required to raise the temperature of one pound of water by 1 degree Fahrenheit.

1BTU = 1055 joule

#HVAC Interview Question:- 14) What types of Air-Conditioning System?

1. Window AC
2. Split AC (Ducted & Non Ducted Split AC)
3. VRV or VRF
4. CAV
5. Package unit
6. DX System
7. AHU (All Air System)
8. FCU (All Water System)
9. AHU + FCU (Air + Water System)

#HVAC Interview Question:- 15) What is By pass factor & Contactor factor?

By pass factor is the percentage of air that pass through a tube of fins without touching fin coil without cool.

Contact factor is percentage of air that pass through a coil by touching the coil and cool down.

#HVAC Interview Question:- 16) What is AHU?

An Air handling unit is used to recondition and circulate air as part of HVAC system. The basic function of the AHU is to take the outside air and recondition it and supply it as fresh air to a building.

#HVAC Interview Question:- 17) Where FCU used?

FCU (Fan Coil Unit) used in Industrial, Commercial & Residential building.

#HVAC Interview Question:- 18) What types of Condenser?

1. Water cooled condenser
2. Air Cooled condenser
3. Evaporative condenser

Water cooled condenser:– a) Shell – Tube condenser b) Shell & Coil Condenser c) Double tube(pipe) condenser

Air cooled condenser: – a) Natural air cooled condenser b) force or mechanical air cooled condenser.

#HVAC Interview Question:- 19) What is Heat Recovery System?

Heat recovery ventilation (HRV) also known as mechanical ventilation heat recovery(MVHR), is an energy recovery ventilation system using equipment know as heat recovery ventilation.

Heat recovery ventilation, also known as mechanical ventilation heat recovery, is an energy recovery ventilation system which works between two sources at different temperatures. Heat recovery is a method which is increasingly used to reduce the heating and cooling demands of buildings.

#HVAC Interview Question:- 20) What types of fans used in HVAC?

1. Axial fan
2. Centrifugal fan
3. Backward inclined fan
4. Forward curved centrifugal fan
5. Blower

#HVAC Interview Question:- 21) What types of compressor used in HVAC?

1. Reciprocating compressor
2. Rotary Compressor
3. Screw Compressor
4. Scroll Compressor
5. Centrifugal Compressor

Important Unit Conversion Of HVAC System

Temperature

• F =  (9/5 x c) + 32
• C = 5/9 x (F – 32)

TON Of Refrigeration

• 1 TON = 12000 BTU/Hr
• 1 TON = 3.516 KW
• 1 TON = 12 MBH
• 1 TON = 3025.9 Kcal/Min
• 1 TON = 200 BTU/Min
• 1 KW = 3412 BTU/Hr

Flow Of Air

• 1 LPS = 2.119 CFM
• 1 CFM = 1.7 CMH
• 1 CMS = 1000 LPS
• 1 CMS = 2119 CFM

Distance

• 1 M = 1000 MM
• 1 M = 100 CM
• 1 M = 3.28 FT
• 1 M = 39 Inch
• 1 FT = 12 Inch
• 1 Inch = 2.54 CM
• 1 Inch = 25.4 MM
• 1 CM = 10 MM

Top HVAC Conversions For Interviews

• 1 MPM = 3.24 FPM
• 1 CFM = 28.3168 LPM
• 1 CFM = 0.4719 LPS
• 1 FPM = 0.00508 MPH
• 1 CFM = 1.7 CMH
• 1 CMH = 4.4 GPM
• 1 GPM = 3.78 LPM
• 3.1 HP = 0.745 KW
• 1 HP = 9550 Btu/Hr
• 1 HP = 2410 K cal/hr
• 1 HP = 0.8 TR
• 1 TR = 1.25 HP