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A fuse is used in an electrical circuit to correct answers Protect the circuit wires from an overcurrent condition How are fuses rated correct answers In amps with a maximum voltage rating What will an ohmmeter measure when testing an open fuse correct answers Infinite resistance What type of sensing element is commonly found in fan and limit controls correct answers Bimetal What is used to sense space temperature in electronic temperature controls correct answers Thermistors ...

What makes a contract legal? correct answers Any verbal or written agreement. Why should hacksaws and power saws not be used when cutting tubing or refrigerant lines? correct answers The small shavings created by the teeth of the saw can enter the tubing and do damage to the components of the system. Why should tube cutters be used? correct answers They produce a square, clean cut and leave no shavings to contaminate the system. What can be used to cut capillary tubing? correct answ...

What kind of heat transfer does not include solids, or fluids correct answers Radiation Capillary tubing should be only cut to length using correct answers Triangular or knife edge file Before beginning any electrical check out procedure, what step should be taken after equipment is disconnected, or breaker is off correct answers Check for voltage When making a flare. The height of tubing above flare is critical correct answers Will not fit into nut Dew point correct answers Tem...

Which component of a residential heating and cooling system heats or cools the home by moving heat? A) Gas furnace B) Air handler C) Heat pump D) Thermostat Answer: C) Heat pump correct answers Answer: C) Heat pump Explanation: The heat pump heats or cools the home by moving heat. It brings heat from outdoor air inside during the winter and takes heat from inside the home and releases it outdoors in the summer. What is the purpose of the evaporator coil in a residential heating and co...

Which of the following measurements would be needed to determine oil furnace combustion efficiency? a. net stack temperature and CO2 concentration b. net stack temperature and CO concentration c. stack temperature and indoor temperature d. stack temperature and fuel pressure correct answers a. net stack temperature and CO2 concentration When combustion is being tested on an oil furnace, high level of smoke and can be corrected by: a. Adjusting the barometric damper. b. Opening the ...

A good evacuation of a refrigerant circuit to remove non-condensables will help insure: A.) higher condensing temperatures B.) higher suction pressures C.) low suction line pressure drop D.) higher efficiency and capacity correct answers D.) higher efficiency and capacity A condensing unit should be mounted on a slab that is level to: A.) allow an accumulated water to evenly run out of the cabinet B.) increase airflow through the fin area C.) prevent the unit from tipping over D.) ma...

a (Centrifugal) correct answers Which of the following compressors are considered a dynamic compressor? a. Centrifugal b. Reciprocating d. Rotary c. Scroll b (Superheated vapor / sub cooled liquid) correct answers What is the condition of the refrigerant as it enters and leaves the condensing coil of a typical light commercial HVAC system? a. Vapor / liquid b. Superheated vapor / sub cooled liquid c. Saturated vapor / saturated liquid d. Hot gas / cool liquid b (Thermal expan...

Generally, vibration eliminators in piping should be installed: A: At a 45 degree angle B: At a 90 degree angle C: Perpendicular to the compressor crankshaft D: Parallel to the compressor crankshaft correct answers D: Parallel to the compressor crankshaft If you purchased ten filter-driers for $100.00, what was the price of each filter-drier? A: $100.00 B: $10.00 C: $1.00 D: $1.10 correct answers B: $10.00 Which of the following jobs requires safety glas...

A high pressure control is usually located on the: A: Condensing unit B: Evaporator C: Cabinet D: Blower correct answers A: Condensing unit A high pressure safety control is: A: Direct acting B: Reverse acting C: Dual acting D: None of the above correct answers B: Reverse acting A low pressure control is usually located on the: A: Condensing unit B: Evaporator C: Cabinet D: Blower correct answers A: Condensing unit A low voltage control...

A suction line accumulator should be used in a residential heating pump only when recommended by the manufacturer if: a. Long refrigerant lines increase system charge over recommended maximum charge b. added oil dilution is required to maintain proper lubrication c. the system has low vapor line pressure drop and accumulator is added to improve efficiency d. the system does not include a high pressure switch or time delay correct answers A. Long refrigerant lines increase system c...

With the condensing pressure and compressor speed remaining constant, a decrease in suction pressure will cause a(n): a. Decrease in compressor capacity and decrease in current. b. Increase in compressor capacity and decrease in current. c. Increase in compressor capacity and increase in current. d. Decrease in compressor capacity and increase in current. correct answers D An indication of non-condensable gas in a refrigeration system is significantly: a. Lower-than-normal suction p...

What electro-mechanical control would you use on a cap tube or automatic expansion valve system to maintain the space temperature? correct answers C: A thermostatic control Open motors are designed to operate at a given temperature rise as indicated on the motor nameplate. What does this mean? correct answers A: indicates the temp. rise over the surrounding air of a motor when the motor is operating at full-load conditions A voltmeter is connected into a circuit in which of the following...

Since 1992, the United States Department of Energy has required that all furnaces sold and installed from that date on must have an AFUE of no less than: A: 70% B: 75% C: 78% D: 80% correct answers C: 78% Many pre-1992 furnaces have efficiencies around _______. A: 10% B: 40% C: 60% D: 80% correct answers C: 60% Today, furnaces with AFUE ratings greater than _____ are available. A: 85% B: 90% C: 100% D: 110% correct answers B: 90% A ther...

Calculate the air volume based upon these conditions: 90,000 BTUH output Return air temperature: 70F Supply air temperature: 110F a. 1,158 CFM b. 1,500 CFM c. 1,800 CFM d. 2,083 CFM correct answers d (2,083 CFM) When measuring CFM using temperature rise method, the furnace blower motor speed should be in: a. Continuous fan speed b. Cool mode speed c. Heat mode speed correct answers b (Cool mode speed) If a single phase electric heat section is supplied with 225 volts and ...

An air conditioning technician is working in the basement of a large B37public building. The technician notices several unsafe and dangerous conditions. Of the following conditions that are noticed, which is the most dangerous and should be reported immediately? A: Gas leaking from a cracked pipe B: An open sewer drain connection C: The basement is unlighted D: None of these are the technician's business correct answers A: Gas leaking from a cracked pipe A service tech...

The Fahrenheit scale is based on boiling water at sea level at what temperature? A: 459 degrees B: 212 degrees C: 180 degrees D: 100 degrees correct answers B: 212 degrees Zero pounds gauge corresponds on the absolute scale to: A: 144 B: 212 C: 14.7 D: zero correct answers C: 14.7 Hidden heat in refrigeration work is referred to as: A: Intensity of heat B: Latent heat C: Heat a thermometer can "sense" D: Cold correct answ...

Charging a heat pump with refrigerant is best accomplished in the _______ mode. A: Heating mode B: Cooling mode C: Defrost mode D: Emergency heating mode correct answers B: Cooling mode Heat pumps can provide both heating in the winter and cooling in the summer. In which mode is the heat pump more efficient? A: Heating mode B: Cooling mode C: Defrost mode D: Emergency heating mode correct answers A: Heating mode Which of the following components is exclusi...

what type of meter is most appropriate when a tech must determine voltage? correct answers voltmeter temp at which moisture begins to condense on objects? correct answers dew point btu's equivalent to 1 watt hour A. 3.418 B. 3.413 C. 3.213 D. 4.314 correct answers 3.413 btu electrical test meter that test volts, ohms and current A. multimeter B. ohmeter C. monometer D. trimeter correct answers multimeter when climbing down a ladder workers must correct answers use 2 h...

What are the five basic components to any schematic? correct answers 1. A power supply 2. A path for the power 3. A load or component that operates from the power. 4. A switch or component that interrupts the power to the load. 5. A legend or key that explains what the various symbols and abbreviations used in the schematic mean. What are the three basic types of wiring diagrams used in the HVACR trade? correct answers 1. The ladder diagram 2. The pictorial diagram 3. The installation...

Which of the following factors affects a customer's level of comfort? a. Air movement b. Humidity c. Temperature d. All of the above correct answers d (All of the above: air movement, humidity, temperature) A cooling load calculation estimates the sensible heat gain of a structure. The maximum sensible capacity of a cooling-only system should be within ____% of this calculated value. a. ±10% b. +10% c. +15% d. +30% correct answers c (+15%) The maximum sensible cooling cap...