HVAC NATE Heat Pump /171 Questions with Correct Answers Assured A+.

HVAC NATE Heat Pump /171 Questions with Correct Answers Assured A+. On an R-22 system, line diameters and lengths are typically specified for a vapor pressure drop that does not exceed what? -Ans 6-7PSI or 6F What is the primary purpose of using flux when soldering copper or brass parts? -Ans Prevent Oxidation The water that results from a defrost cycle of an air to air heat pump(runoff) must? -Ans Drain off and away from the outdoor coil. Why must the runoff be drained off and away from the outdoor coil? -AnsExcessive ice can build up on the bottom of the coil and can reduce capacity. What is the component that reduces sound transmission and prevents water leaks of a package heat pump installed on a roof? -Ans Curb Gasket Why do you need to add a control for a heat pump indoor coil that is installed on a fossil fuel furnace? -AnsSo the heat pump and furnace do not operate at the same time in normal heating. What happens when you energize a hermetic refrigeration compressor and the system is in a deep vacuum? -AnsMotor windings could become damaged. What needs to happen in order to consider an evacuation to be complete? -AnsSystem should be evacuated to a vacuum of 500 Microns or below. A system is supplied from the factory with charge for a 15 foot line set. The data plate shows the required system charge to be 5 pounds 10 ounces. The line set uses a 3/8 inch liquid line and is 25 feet long. The manufacturer's instruction sheet specifies 0.6 ounces of refrigerant to be HVAC NATE Heat Pump /171 Questions with Correct Answers Assured A+. added for each added foot of refrigerant line length. How much refrigerant is needed to completely charge the system? -Ans6lbs Where are drive slips typically installed? -AnsOn the shorter sides of rectangular duct. What is a necessary check to properly set a heat anticipator? -Ans Heating control circuit amperage draw. A heat pump operating in normal ice free conditions maintains a certain temperature difference between the outdoor coil temperature and the surrounding outdoor ambient. What is this temperature referred to as? -AnsCoil TD. What is the smallest refrigerant leak that an electronic leak detector should be capable of sensing? -Ans .o5oz per year. When checking the pressures in an operating system with a manifold gauge set, will refrigerant oil in a hose will have an effect on the gauge? -AnsNo What is the absolute pressure at sea level if a gauge pressure is 35 psig? -Ans49.7psia 100,000 BTUH output furnace. Return air temp is 65F. Supply air is 135F. What is the CFM? -Ans 1323CFM What is the best method of repair when a residential supply diffuser is noisy because of a loose vane? -Ans Replace the diffuser. When performing preventive maintenance on a heat pump what should the technician check and why? -AnsOutdoor fan. To be certain it runs freely with no binding. What is the effect of 170 volts supplied to a 208/230 volt compressor? -Ans Would cause the current to increase and the motor may trip on overload. On a service call for a cooling problem with a heat pump, your inspections find a liquid line that has condensation on it. What is most likely to cause this? -Ans Restriction in the liquid line. What is a reason for cool air complaints when a heat pump is operating in the heating cycle? - AnsExcessive supply air velocities. The following measurements are recorded on an operating heat pump system. The heat pump is operating with the compressor only with no auxiliary heat: • Heat pump only supply air temperature 92°F • Heat pump only return air temperature 70°F • Outdoor temperature 54°F • Supply air temp. /auxiliary heat ON 115°F • Return air temp. /auxiliary heat ON 70°F • CFM 1228 What is the heating capacity in BTUH? -Ans29,177 BTU/H Inadequate heating can be caused by what? -AnsDirty or clogged air filter.