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HVAC BOMA Prep: Questions With Detailed Answers
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HVAC BOMA Prep: Questions With Detailed Answers
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HVAC BOMA Prep: Questions With Detailed Answers In an A/C system where are comes from both a hot duct and a cold duct that issupplied from a mixing terminal is called a dual duct system. Correct Ans - Duel duct system
An A/c system in which the zone control is obtained by mixing hot and cold air at the unit in response to a room thermostat is called a... Correct Ans - Multizone system
What do heating and cooling calculations take into consideration? Correct Ans - Sensible heat and latent heat
Which does not provide sensible heat gain? Correct Ans - Heat from cooking or hot baths (latent heat has to do with moisture)
Which is the way that solar radiation disperses in a building? Correct Ans - Transmitted directly to the interior of the building, absorbs by glass, reflected into the building.
How can outside air get into the air conditioning spaces? Correct Ans - Infiltration through the walls, infiltration through the swinging doors, air induced by replaced exhaust
In commercial buildings heat generated by lights do not seriously affect the control of the heating system. T/F Correct Ans - False
The human body's feeling of well being is dependent on what? Correct Ans - The body's metabolism
Which natural law has the greatest bearing on the science of air conditioning? Correct Ans - Charles Law
Why is a pitch pocket commonly used? Correct Ans - To protect the piping and seal the roof from refrigeration lines passing through it
Which is an evaporative type condenser and what governs its cooling? Correct Ans - A cooling tower governed by the wet bulb temperature On an evaporative condenser what is the purpose of the eliminator? Correct Ans - Its to separate the moisture carryover
What is the amount of heat necessary to raise the temperature of one pound of a substance, one degree Fahrenheit? Correct Ans - Specific heat
What is the amount of heat necessary to change a liquid to a vapor with no change in temperature. Correct Ans - Latent heat
What is the difference between a pump, a fan and a compressor? Correct Ans - Pumps pump liquid, fans and compressors pump air.
Which of the following checks should be made of a blower-drive? Correct Ans - Check the blower belts for cracks and wear, check the motor bearings for wear, check the blower bearings for wear.
Which of the following is a good rule to follow when checking air filter? Correct Ans - Air filters should be of the size and type recommended by the equipment manufacture
When one of the three phases of a motor fails, how will a motor react? Correct Ans - A winding will run hotter, the motor will generally not start, the two phases will draw 1 1/2 times more current.
When megohming a motor winding what is the rule of thumb to find an acceptable rate of resistance to ground? Correct Ans - 1000 ohms/volt
Which of the following may be the cause of improper air distribution? Correct Ans - High pressure drop thru ducts and fittings, dirty filters, incorrect fan speed.
Friction losses of pressure in ducts systems occur in what? Correct Ans - In elbows, along duct walls, with increase in air speed
Which may cause faulty fan operation? Correct Ans - Loose belt drive, restricted air intake, improper fan bearing lubrication
What is the first step in troubleshooting procedures? Correct Ans - Analyze the complaint If the complaint is "too little heat" and the burner is short-cycling the most likely cause is what? Correct Ans - Thermostat is out of adjustment
Excessive combustion noise is most likely cause by what? Correct Ans - Improper burner adjustment
When a complaint is "too much heat" and the burner is running continuously the most likely cause is what? Correct Ans - Faulty wiring
In case of a failure of burner to start, the most likely cause is what? Correct Ans - A blown fuse
What is the most probable cause of a burner to start? Correct Ans - Power failure
When the complaint is "too much heat" and the heat element operates continuously the most likely cause is what? Correct Ans - Faulty control wiring
If the complaint is "too much heat" and the electrical wiring is short-cycling the most likely cause is what? Correct Ans - Thermostat heat anticipator set too low
In case of an electrical heating system not starting, the most likely cause is what? Correct Ans - A blown fuse
A psychometric chart is a graphic representation of what? Correct Ans - Thermodynamic properties
Heat flows in one direction, usually from... Correct Ans - A position of higher temperature to a position of lower temperature.
What are the three main ways heat transfer takes place? Correct Ans - Convection, conduction, and radiation
Which of the following material is the best conductor of heat? Correct Ans - Metal Heat will continue to flow between two bodies until they have become the same... Correct Ans - Temperature
Enthalphy refers to what? Correct Ans - Heat content of a refrigerant (both latent and sensible)
Psychrometric is the science of dealing with the relationship between what? Correct Ans - Humidity and the atmosphere
Which is not one of the four environmental qualities provided by complete air-conditioning systems? Correct Ans - Electrostatic suppression
Translated into degrees Fahrenheit which is the value of absolute zero? Correct Ans - Minus 460 degrees Fahrenheit
When water vapor is considered in a relationship of air, which statement is most nearly correct? Correct Ans - Mixing air on a mechanical basis causes a humid condition
Specific humidity may be defined as... Correct Ans - An actual weight of water mixed with a pound of dry air
The term wet-bulb depression means... Correct Ans - The difference between a dry-bulb and a wet-bulb reading on a sling psychrometer
The active element of a relative humidity meter that's used in a humidistat is...
Correct Ans - Horse hair
Which statement is incorrect? Correct Ans - Evaporative cooling is a variable heat process
What volume of air will move through a duct 24" x 18" with a velocity of 450FPM Correct Ans - 1350 CFM (24 x 18 divided by 144 x 450 equals 1350)
The element which makes up the greatest volume of air is what? Correct Ans - Nitrogen
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