HVAC Interview Questions and Answers
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Top HVAC Interview Questions and Answers
- Q) Mention some Pumps supply fittings?
- A) Shutoff valve, Pressure gauge, Union flexible Connector, strainer, Drain cock, eccentric reducer, test point and thermometer.
- Q) Mention some pumps return fittings?
- A) Flexible connector, check valve, temp sensors, strainer, check valve, Eccentric reducer, temp sensors, gate valve.
- Q) How many kinds of motorized damper?
- A) Smoke damper, Motorized fire and volume damper.
- Q) Define VFD?
- A) Variable frequency drive helps to handles the motor speed by handling the frequency which is applied to it. We can use VFD with AHU and chillers, so that, it helps to controls the pumps RPM.
- Q) What is meant by VAV and how it works?
- A) Before VAV and working procedure, Initially, we need to talk about Pressure dependent and pressure independent.
Pressure Dependent: On the basis of static pressure, the air volume is carried by the terminal unit in the primary air duct.
Pressure independent: By limiting the flow rate through box with the help of flow sensing devices. They can control minimum and maximum cfm which can carries and varies independent of the static pressure in primary air duct.
Basically, every HVAC system installed at initial point having VAV terminals independent. The pressure independent systems can be handled and also corrects the airflow from every terminal point.
- Q) How can we handle and measure the noise level in A/C system?
- A) By DB level, Noise level can be calculated. Noise level will be controlled by giving acoustic to panels, we should switch to sound attenuates when the sound crosses the set noise.
- Q) Generally, In HVAC systems, how many types of duct shapes we used?
- A) Oval shape, Spiral shape, round and rectangular shapes are used frequently.
- Q) Where can we use fire damper, splitter and non return damper?
- A) Fire Dampers: Fire dampers helps to stop the fire wherever duct passes through the fire walls.
Splitter damper: For balancing the air proportionally, these dampers are used to split the main duct.
Non Return Dampers: Only in ventilation system, Non return dampers are used. It is also used to stop the air flow back in the duct area.
- Q) How many types of exhaust fans are used to extract the air?
- A) There are four types of fans we used frequently such as Axial type propeller fan, twin fan, direct driven, and centrifugal fan.
- Q) What you use to control the vibration of chillers and AHU?
- A) By using flexible bellows, Kinetic chain, Spring vibration isolators and rubbers pads we can control the vibration.
- Q) What are the main things you consider while planning the layout of plant room?
- A) Initially, space, site orientation, Location of the plant room, tailor or readymade A/C unit.
- Q) How many types of Louvers are used? What are them?
- A) Total seven louvers are used they are Sand trap, fresh air louvers, door, acoustic lovers, return air, back draft and supply air louvers.
- Q) How many types of chillers we used?
- A) Water and air cooled chillers, scroll chillers, screw, reciprocating and centrifugal chillers.
- Q) Mention some of the security checks in chillers?
- A) Anti-freeze, flow switch, pump interlocking, chiller, oil pressure, high pressure cut out, high suction superheat.
- Q) What are the ducts internal installation procedure?
- A) 25MM inside and 50MM outside are the thickness insulation of the ducts of both in and outer side and the ducts travels through unconditional spaces.
- Q) How can we find velocity of the FPM?
- A) We should know about Friction and GPM. Now we need to coincide them in a graph to get the velocity. We need to count each year cycles data, to find the FPM, in annexure we need to search. Now the FPM we get will refer as roof, Now take 20 percent of roof for FPM in risers and 20 percent of risers to get runners.
- Q) Explain Fan Coil Unit (FCU)?
- A) Fan Coil Unit is an friendly device which helps to heat or cool the heat exchange. FCU device is a part of HVAC system which is found in residential, industrial buildings, and commercial.
- Q) Explain Air Handling Unit (AHU)?
- A) Air Handling Unit is a device which helps to circulate air to heat, ventilation and also air conditioning system. The main key role of AHU of is take an outer air, again recondition it now supply it fresh air.
- Q) What is the role of HAVC engineer?
- A) HVAC engineer handles designing, maintenance, heat repair, air conditioning, refrigeration system, cooling, installation and ventilation.
- Q) Define HVAC system?
- A) Commonly we use HVAC in industries like heating and cooling. To avoid the usage of acronyms, energy center uses. The combination of three functions like air conditioning, ventilation and heating into one system for buildings.
- Q) In refrigeration system compressor is used for which purpose?
- A) To increase the refrigerant temperature and pressure.
Q) In the following which is referred as heart of vapour compression system?
- A) Compressor
- Q) What is the main functioning of condenser in refrigeration system?
- A) The condenser works to reduce the refrigerant heat in refrigerant system.
- Q) In which of the following compressors, piston is used in?
- Centrifugal Compressor
- Reciprocating Compressor
iii. Rotary Compressor
- A) Reciprocating Compressor
- Q) Which valve can handle the refrigerant flow to evaporator?
- A) The expansion valve will handle it.
- Q) How many types of condensers are them?
- A) There are three types of condensers.
- Q) In Refrigerator and water cooler, which tube is used for expansion device?
- A) Capillary tube is works as an expansion device.
- Q) What do you know about Variable air volume and dual duct system?
- A) Variable air volume is considered as air conditioning system, heating and ventilating. Not similar to CAV systems, at variable tempt VAV provides constant airflow, at particular tempt Variable air volume system varies.
- Q) Define Centralized air system?
- A) The split system is also referred as cooling central system, it contains condenser coil and condenser which is an outside cabinet, the indoor coil was installed with furnace and the compressor pumps a chemical is known as system refrigerant.