 ## Thursday, September 13, 2018

### 100+ Most Repeatedly Asked HVAC Interview Questions With Answers (Free PDF)

1) What is the Unit of Heat?
Ans) Units: BTU (British Thermal Units) 1BTU: It is the amount of energy required to raise 1 Degree Fahrenheit temperature of 1 Pound of water (OR) It is the amount of heat when added to 1 Pound of water increases the temperature of water to 1 Degree Fahrenheit1 Lb = 0.45 Kgs (or) 1kg = 2.2 Lbs. Types of Heat:-
Sensible Heat: It can be sensed or measured by an ordinary dry bulb thermometer. Eg: Human body temperature can be measured using thermometer.
Latent Heat: It can’t be sensed or measured by an ordinary dry bulb thermometer. It is a hidden heat. Latent heat is absorbed or released when ever there is a change in phase. Eg: When the water becomes vapor and vice versa.

2) What is TON & 1 TON =?
ANS) TON or Ton of refrigeration: It is the amount of energy required to Freeze 1 pound of water in 24 hours (or)It is the amount of energy required to Melt 1 Ton of Ice in 24 Hours

3) Volume of Air is measured in?
ANS) Volume of air is measured in terms of: CFM = Cubic Feet per Minute CMH = Cubic Meter per
HourM3/Sec = Cubic Meter per Second L/Sec = Liters per second CMH = 1.7 x CFMCFM = 2118 x m3/sec CFM = 2.119 x l/sec

4) What is ASHRAE?
Answer- ASHRAE: American Society of Heating Refrigeration and Airconditioning Engineers.

5) What is the Room Temperature that you maintain in any room?(1M)
Answer- 24 Degree Celsius or 76 Degree Fahrenheit

6) CFM = Velocity(usually 1500) * Area in Sqft {(d/2)^2*3.1416/144}

7) 1 ton = 12000 BTU/hr = 3.516 KW.

8) Heat Transfer Coefficient (U):
1 (Btu/hr. sqft. *f) = 5.6782 (watt/m^2 . Calvin) Thermal Conductivity (K): 1 (Btu/hr.ft.*f) = 1.73 (watt/m. Calvin).

9) What is CFM
Answer - Cubic feet minute, it is the unit of air flow.

10) What is Aspect Ratio?
Ans: - it is the ratio between ht n length of the duct generally we take 1:2 can vary with space and size up till 1:4.

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