NATE CORE STUDY GUIDE QUESTIONS WITH COMPLETE SOLUTIONS

Mineral oils are not to be used with HFC alternate refrigerants: - True Flue gas temperatures at which the high-efficiency furnaces operate typically is: - 100 to 275 degrees Which of the following type of controllers are used in HVAC applications: - PI According to ASME, safety valve of the boiler should be tested for every _____ days: - 30 In Psychrometric ________ indicates which of the following: Dew point temperature line: - Chart curve boundary 1 horsepower = _________ watts: - 746 Dew point temperature is the temperature at which web bulb temperature is _________ the dry bulb temperature: - Equal to The speed of 4 pole motor is about ______ rpm: - 1800 A suction line accumulator is used for which of the following purpose: - Prevent liquid refrigerant from entering compressor Locked Rotor Ampere (LRA) current of a motor will be typically ________ times the normal running current of the motor: - 5 to 7 times Which of the following motor is best suited for speed control applications: - DC Shunt motors Square cut or butt joints are not permitted on corners of ductboard sections: - True A thermostatic expansion valve modulates to maintain suction _____: - Super Heat An amperage is the measurement of which of the following: - Current A ______ is used to control the flow of refrigerant in an air conditioning or refrigeration system: - Solenoid valve Which of the following is not available in heat pump: - low pressure sensing switch Which of the following will never get energized during defrost mode in a heat pump: - Outdoor Fan _______ is the cubic feet of the mixture per pound of dry air: - Specific Volume Which of the following motors are more rugged and can handle more load: - Ball bearing type motors ________ compressors operate most efficiently with a high molecular weight, high specific volume refrigerant: - Centrifugal The minimum Annual Fuel Utilization Efficiency (AFUE) available is set by federal law for most furnace types at _______ : - 78% ______ of a fan is the total pressure diminished by the fan velocity pressure: - Static Pressure Suction pressure at the ________ is governed by the design of the evaporator: - Compressor Which of the following compressors have pulsations: - Reciprocal Compressors When a system is circulating an excessive amount of oil, the oil indicator may become saturated. This results in the indicator to appear in _______ color - Brown The horsepower required for any fan or blower varies directly as the ______ of the speed: - Cube With increase in evaporator load, the liquid refrigerant evaporates at _____ rate: - Faster The purpose of an accumulator is to prevent ______ damage due to slugging of refrigerant and oil: - Compressor Higher the suction pressure, the greater the efficiency of the _______: - Compressor The refrigerant holding capacity of the accumulator is based on an average conditions of ______ percent fill under running conditions: - 65% Fuse is used for which of the following protection: - Short circuit Shaded pole motors are not self starting like capacitor start motors: - False ______ are preferred for high volume and low pressure applications: - Axial fans Remote condensing units are likely to have long horizontal suction lines or vertical risers exceeding ________ in height in the suction lines: - 3 ft The AH compressors are rated in ______: - BTU/H Which of the following device oppose any change in the circuit voltage: - Capacitor Which of the following has least tendency to leak: - R11 - 3/4 HP