HVAC NATE Heat Pump Questions with 100% Correct Solutions, A+

A resistance reading of infinity across the "R" terminal and "S" terminal of a compressor motor indicates a(n) _________. - Correct Solution open motor winding An acceptable capacitance reading for a run capacitor is _____ the microfarad rating printed on the capacitor. - Correct Solution plus or minus 10% of. How may CFM per ton of cooling? - Correct Solution 400CFM per ton How many BTUh per ton of cooling? - Correct Solution 12,000BTUH per ton What is measured to determine the total resistance to airflow in a ductwork system? - Correct Solution External static pressure at the air handler or furnace What is the output of a residential electric furnace when the voltage impressed is equal to 235 V and its current draw is 40 A? - Correct Solution 32,080 Btuh Btuh = W x 3.413 W = V x A What is the total CFM: Voltage: 240V Amps: 40A Return air: 70 Supply air: 105 - Correct Solution 867 cfm cfm = (voltage x current x 3.413) / (temperature rise x 1.08) What is the recommended face velocity for air leaving a supply register? - Correct Solution 700 ft/min Temperature readings taken 6 in. from the compressor discharge line should never exceed ___________ F. - Correct Solution 225°F A system should operate at least _____ before heat measurements are taken - Correct Solution 20 minutes What gas should be purged through a refrigerant circuit to prevent the formation of oxides whenever brazing is being done? - Correct Solution Dry Nitrogen What certification is required before a technician is permitted to work on air conditioning and heat pump systems? - Correct Solution EPA Section 608 certification What is a reason for cool air complaints when a heat pump is operating in the heating cycle? - Correct Solution Excessive 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? - Correct Solution 29,177 BTU/H Inadequate heating can be caused by what? - Correct Solution Dirty or clogged air filter. To minimize noise problems in residential duct systems, what is the range (recommended to maximum) of design air velocity in the rectangular main supply trunk? - Correct Solution 700 to 900 fpm conditions while checking a packaged heat pump in cooling. • The unit has a piston type metering device on both the indoor and outdoor coils. • Outdoor temperature 75°F • Superheat 55°F What is wrong with the system? - Correct Solution Undercharged. What will you get when a capillary tube is overcharged? - Correct Solution low superheat and high sub cooling What is the effect of a low charge on the switchover operations of a reversing valve? - Correct Solution Reversing valves are less likely to transfer if charge is low.