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A series of multiple-choice questions and answers related to heating, cooling, and air conditioning (hvac) systems. It covers various aspects of hvac operation, including thermostat function, demand factors, heat transfer principles, and electrical safety regulations. Suitable for students studying hvac or electrical engineering, as it provides practical examples and reinforces key concepts.
Typology: Exams
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The correct operation of a properly functioning domestic gas furnace would be: A - the gas valve closes, B - the room is warm and the thermostat contacts open, C - the fan stops D - the heat exchanger and the air in the plenum cools.
Choose from the list above to correctly perform this operation.
B,A,D,C A,B,C,D C,D,A,B D,C,A,B - โ โ B,A,D,C
Temp tells system to shut off first Fan stops last to allow plenum to cool properly
What is the calculated demand factor for an electric thermal storage heating system rated at 20kW in a single dwelling?
15,000 Watts 25,000 Watts 20,000 Watts 17,500 Watts - โ โ 20,000W
Which term best describes the following. The heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit.
Joule Watt Calorie British Thermal Unit - โ โ BTU
Calorie = metric A high limit control in a hot water heating system is:
3 m 5 m - โ โ 3m
Equipment that contains a hermetically sealed motor compressor comes with a marking from the manufacturer that is different from most other pieces of electrical equipment. What is that marking?
a) minimum overcurrent device B) rated-load current C) horsepower rated D) full-load amps - โ โ B) rated-load current When a residential air conditioning load is used in the residential service calculation, what will it be added in at? 100% 125% 40% 75% - โ โ 100%
If two or more heating fixtures, such as baseboard heaters, are connected on a single heating branch circuit, what must the overcurrent device not exceed? 20A 30A 25A 35A - โ โ 30A
Where must the automatic thermostatic control be when baseboard heaters are used to heat a dwelling unit?
on each branch circuit in each room on each unit in each overcurrent device - โ โ Each room
D) The furnace must be reached before the panelboard. - โ โ A) No person needs to walk by the furnace to operate the circuit breaker What does a thermocouple consist of? 4 dissimilar metals 2 dissimilar metals 3 dissimilar metals 5 dissimilar metals - โ โ 2 dissimilar metals Under what conditions can Class 1 circuit conductors be run in the same raceway as power conductors?
A) Conductors must have the same voltage applied as the power conductors B) Class 1 conductors cannot be in the same raceway as power conductors. C) It can be done when the raceway also has class 2 conductors pulled in. D) Conductors must be insulated for the maximum voltage rating. - โ โ D) Conductors must be insulated for the maximum voltage rating.
When a fireplace uses a self-generating system, what is the small amount of energy required by the gas valve is supplied by?
LVT cable a thermopile a thermocouple an RTD - โ โ Thermophile What does each region of the country have a different number of, which affects the heat requirements to maintain a comfortable living temperature?
temperature ranges degree days sunny days rainy days - โ โ Degree days A heat pump can also be used to cool the building when the outside air temperature is warm. How is this achieved?
The direction of rotation of the motor is reversed.
A) The grounding conductor only B) Both ungrounded conductors C) All circuit conductors D) The grounded conductor only - โ โ B) both ungrounded conductors What is one of the major differences between Class 1 and Class 2 circuits?
A) Any failure in Class 2 circuit wiring would introduce a direct fire or life hazard; Class 1 would not B) Any failure in Class 1 circuit wiring is unlikely because the circuit has redundant wiring C) Any failure in Class 1 circuit wiring would introduce a direct fire or life hazard; Class 2 would not D) Any failure in Class 2 circuit wiring is unlikely because the circuit has redundant wiring - โ โ C) Any failure in Class 1 circuit wiring would introduce a direct fire or life hazard; Class 2 would not
What is the maximum voltage drop that the CE Code allows on a heating branch circuit?
Where to place thermostat? - โ โ Inside wall, away from direct sunlight and not in a dead-air space What is the maximum temperature adjacent materials may be subject to when installing heating units? Question options:
a) 60 degrees C b) 90 degrees C c) 105 degrees C
d) 75 degrees C - โ โ b) 90 degrees C
What is the simple heat-loss of exterior wall formula? - โ โ Heatloss = HTF(w/m^2) x Area(m^2) x DTD (Celcius) What is the minimum breaker size for overcurrent protection on a circuit supplying a 20 kW, 240 V, single phase boiler? (equipment is marked for continuous operation at 100%) Question options:
a) 90 amp b) 70 amp c) 125 amp
d) 100 amp - โ โ 90A
Rated for 100% continuous T.13(83.33) = 90A breaker Calculate the LRC of a 1.5 hp three-phase induction motor rated for 208 volts
6.6Ax6 = 39. When #18 AWG conductors of a Class 1 circuit are run between pieces of equipment, they must be protected by overcurrent devices that are rated or set at not more than what strength?
16-104 (1b)
A heating cable is to be used in a Wet Location. What must be marked on the cable for this usage?
In a water-to-air heat pump system, the water is the _____.
heat sink heat dissipater cooling medium heat source - โ โ Heat source If the FLA of a 1/2 hp three-phase motor is 4.4 amps, what voltage is it connected to?
575 Volts
200 Volts 208 Volts
115 Volts - โ โ 115V
In most instances, what is the RLC of a hermetic refrigerant motor-compressor?
96.1% of the MCC 64.1% of the MCC 32.1% of the MCC 16.1% of the MCC - โ โ 64.1% of the MCC For individual motor-compressor equipment, what is the minimum ampacity of the branch-circuit conductors
not less than 80% not less than 140% not less than 125% not less than 100% - โ โ 125%
Heating fixtures shall be installed to avoid which of the following from occurring?
A) Heat transfer is not obstructed B) To conflict with the building design C) To prevent the unnecessary heating of additional spce D) Heating fixtures can be installed as determined by the installer - โ โ A) Heat transfer is not obstructed
What is the minimum size overcurrent protection required for a 12.5 kw, 240 volt single phase furnace? 60 amp 70 amp 80 amp 90 amp - โ โ 12500/240=52A 52x1.25=65A T.13= 70A What is a schematic diagram used for?
The location of components The relative size of components The logical operation of the components The electrical ratings of the components - โ โ The logical operation of the components If you wanted to find out the relative position of components in a heating system and the wiring between them which one of the following would you look at?
A wiring diagram An elevation drawing A schematic diagram A specification sheet - โ โ Wiring Diagram How much power is required to heat a 40 gallon water heater 92degress in one hour? - โ โ 8995W
40gallon x 8.34lbs/gallom = 333.6lbs 333.6lbs x 92deg = 30691.2 BTU
