HVAC pre-test questions and answers graded A+

HVAC pre-test questions and answers graded A+ Two basic categories of chillers are Compression cycle and absorption The 5 requirements for comfort are temperature, humidity, filtration, ventilation and _______ Circulation The primary function of an expansion device is to: Reduce pressure on liquid refrig, regulate flow, lower the boiling point below the temp of the load All of the above The wet-bulb depression is The difference between the dry-bulb and wet-bulb temperatures The dew-point temp is Temperature when the moisture begins to condense out of the air How many BTU's are required to change 1 lb of ice at 20 degrees to steam at 220 degrees 1304 btu/h If an r-12 refrigeration system is operating with a 25.4 psig suction pressure what is the evap superheat 9 degrees Faranheit On an r-11 or R-123 system the refrigerant removal process normally starts with the removal of Liquid refrigerant The condenser in a refrigerant system: desuperheats, condenses the vapor from compressor, subcools All of the above The human body gives off heat by? Convection, Radiation, Conduction All of the above If the temp remains constant and the volume that a gas occupies increases the pressure will... Decrease Transformers are rated using Volt-amperes Measuring velocity pressure in a duct indicates the speed at which the air is moving A solid material exerts a pressure or force downward only Pure water boils at 212 deg at which of the following standard conditions? 12.967 psi, 13.967 psi, 14.967 psi, or 15.967psi 14.967 psi Which of the following would allow a system to operate more efficiently? Condesner that had refrigerant leaving with 10 degree of subcooling, 15 degree of subcooling as 100% vapor 10 degree superheat Leaving with 10 degree of Superheat One watt of electrical energy is equal to 3.413 Btu Rotary compressors are used primarily in Domestic Refrigerators The water circuit in shell and coil and coil-type tube in a tube condensers must be cleaned chemically When a water regulating valve is used to control the head pressure of a water cooled system, the valves spring is acting against which pressure to modulate the water flow Head pressure of the system The standard atmospheric pressure at sea level