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Boma hvac Questions with correct answers | latest update | Complete Solution 2024
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Exam of 25 pages for the course FEMA at FEMA (Boma hvac)
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Boma hvac✅✅
(T/F) A Compressor raises the pressure and lowers the temperature of the
refrigerant - -False
3 laws dealing with hvac -✅✅-Boyles , Charles, and daltons
A btu is the amount of heat required to change - ✅✅-One pound of water
one degree Fahrenheit
A current magnetic relay opens and closes based on - ✅✅-The current in
the run winding
✅✅-High stability
A desirable physical property of refrigerant is -
A direct expansion - type evaporator is also called a - ✅✅-dry-type
evaporator
A direct expansion type evaporator is also called a - ✅✅-Dry type
evaporator
A fluid is anything that - ✅✅-Flows
A least likely cause of head pressure problems is a - ✅✅-An oversized
cooling tower
A psychrometric chart is a graphic representation of - ✅✅-Thermodynamic
properties
A psychrometric chart is a graphic representation of - ✅✅-Thermodynamic
properties
A pump out unit is used to - ✅✅-Transfer refrigerant from the machine to an
external source
A rotary compressor is what type - ✅✅-Positive displacement compressor
A sensing bulb for a txv should not be Installed ? - ✅✅-On a fitting in a trap
or pocket or on the bottom of the line
,a shell and tube transfers heat - ✅✅-Outside of the tubes to the inside
✅✅
A split phase motor can use what to energize and de-energize the start
winding ? - -Potential relay, current relay, and a centrifugal switch
✅✅
A system which application of heat is the secondary process is -
-Terminal reheat
A systematic check of a cooling unit is - ✅✅-Check the evaporator coil,
condensate pan, tubing for signs of oil leaks, and the electrical wiring
A thermometer indicates - ✅✅-Sensible heat
A ton of refrigeration is equal to - ✅✅-288,000 BTU / 24 hours
A typical evaporator operating temperature in an ac system is - ✅✅-40
degrees Fahrenheit
✅✅
A typical super heat for an evaporator operating under normal conditions
would be - -8 to 12 degrees
✅✅
Acceptable range of resistance to ground when megahoming -
-1000/ohms/volt
✅✅
Adding a small amount of refrigerant to an undercharged system will cause -
-Rise in head pressure
✅✅
Air comes from a hot duct and a cold duct that is supplied by mixing terminals
is called - -Dual duct system
Air conditioning is the control of - ✅✅-Temperature, humidity, purity, and
distribution of the air
Air flow through a duct has highest velocity near - ✅✅-The center of the duct
✅✅
An ac system that provides complete sensible heating and cooling and latent
heat utilization is what type of system - -All air system / all air heat pump
An example of an axial flow fan is - ✅✅-A propeller fan
, An oil safety switch is operated by what - ✅✅-The difference between oil
pressure and crankcase pressure
At a constant pressure, the volume of a gas varies as to the absolute
✅✅
temperature and at a constant volume the pressure of the gas varies directly
with the absolute temperature. This is known as - -Charles law
✅✅
At what locations in a refrigeration system does the saturation pressure
correspond to the saturation temperature - -Evaporator and condenser
Atmospheric pressure at sea level is - ✅✅-29.92" hg
✅✅
Calculations involving heat loads of people take into consideration heat due to
- -Latent heat and sensible heat
✅✅
Can the performance of a fan at various speeds and air densities be predicted
?- -Yea through fan curve calculations
✅✅-A VFD
Capacity control on a chiller is by use of -
Centrifugal compressor is what type - ✅✅-Dynamic
Chillers use what type of compressor - ✅✅-Centrifugal compressor with a
turbine type impeller wheel
✅✅-Ratio of absolute suction and discharge pressure
Compression ratio is -
Compressor motor and condenser fan motor are wired - ✅✅-Parallel
✅✅
Condensing units draw the most amperage when the suction pressure is -
-30 psi
Conductance is a term used to denote heat flow through - ✅✅-Non
homogeneous material
Conduction heat is transferred by - ✅✅-Contact
Convection heat is transferred by - ✅✅-Movement of water fluid or air
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