HEAT PUMP ESCO QUESTIONS WITH SOLUTIONS ALL CORRECT 2024 LATEST UPDATED GRADED A+., Exams of Heat and Mass Transfer

Download HEAT PUMP ESCO QUESTIONS WITH SOLUTIONS ALL CORRECT 2024 LATEST UPDATED GRADED A+. and more Exams Heat and Mass Transfer in PDF only on Docsity! H EAT PUMP ESCO QUESTIONS WITH SOLUTIONS ALL CORRECT 2024 LATEST UPDATED GRADED A+. An air-to-air heat pump has many of the same components as an air conditioning system. The major difference is that a heat pump also has an - Solution Reversing valve What is the difference between "demand defrost" and "timed defrost"? - Solution Demand defrost happens only when needed and timed defrost is based on time/temperature. The thermostat that controls the auxiliary electric heat according to the outdoor temperature is called the; - Solution Outdoor ambient thermostat The outdoor temperature at which the heat pump provides the same amount of heat as the heat loss of the conditioned space without an auxiliary heat is known as the; - Solution Initial balance point At what temperature is an outdoor ambient thermostat normally set? - Solution Slightly above the initial balance point. The outdoor coil is frozen solid on a "no heat" service call. The most likely reason is; - Solution The outdoor fan is inoperative. In order to determine a heat pumps' balance point, you must first calculate; - Solution The building's heat load. When a heat pump is used for heating and cooling, the system is sized by the; - Solution Cooling load. A high efficiency heat pump system designed to function from high to low ambient conditions below 10*F, may have? - Solution Two outdoor coils with each one incorporating a dual stage compressor. Room thermostats for heat pumps should be installed; - Solution As near to the main return air grill as possible. When the heat pump compressor has malfunctioned, the customer has the option to switch the system into; - Solution Emergency heat mode. Start up with a night set back digital thermostat requires the technician to always; - Solution Teach the customer how to program the thermostat. The heat pump defrost board can be manipulated by the technician to; - Solution Simulate the defrost cycle. The air-to-air heat pump outdoor unit is most efficient if located; - Solution In a moderate climate zone. Which of the following are innovations that may be found on new high efficiency units? - Solution ECM fan motors. How may a lockout (impedance) relay be reset? - Solution Simply disconnect power to the unit momentarily. The temperature difference between the 1st and 2nd bulbs for heating on a heat pump thermostat is; - Solution Approximately 2*F SEER is calculated by; - Solution Dividing the Btu's removed by the watts consumed during the cooling season. If the indoor fan is operated at an excessive speed in the cooling mode; - Solution The system will not properly remove the humidity from the conditioned space. The most preferred method of charging any system in the field is; - Solution By weight. What is the industry standard for deep vacuum? - Solution Maintain 500 microns for 15 minutes. Good service practice for installation of a reversing valve includes; - Solution Use heat paste and wet rags while brazing in the new valve. When a heat pump is operating in the heat mode, the suction line at the compressor; - Solution Cold and sweaty The use of a scroll type compressor on a heat pump can eliminate the need for a; - Solution Suction line accumulator. A heat pump operates satisfactorily in the cooling mode, but not in the heat mode. This could be caused by; - Solution A stuck check valve or clogged TXV screen. It is not always a good idea to immediately connect a standard gauge manifold set and hoses to a heat pump when a problem is suspected because; - Solution The charge is critical, sometimes to 1/2 oz. refrigerant. Which component is responsible for changing the direction of the flow of refrigerant? - Solution Reversing valve. Some heat pump systems use a ______________ as a metering device. - Solution Fixed orifice. The slide valve and piston in the reversing valve is actuated by pressure directed through the; - Solution Solenoid and pilot valve. During the heating cycle, the outdoor coil is use as; - Solution The evaporator. During the cooling cycle, the indoor coil becomes; - Solution The evaporator. During the defrost cycle, the outdoor fan is usually; - Solution Turned off. Heat pump systems which use a thermostatic expansion valve at each coil will also have; - Solution A by-pass lines with check valves. Refrigerant flow through the compressor; - Solution is always the same regardless of operating mode. Because of the possibility of liquid flood-back, a heat pump that uses a reciprocating compressor should be equipped with a; - Solution Suction Accumulator. A scroll type compressor; - Solution is less susceptible to damage from liquid flood-back. On a split system heat pump. A "no heat/no cooling" service call, you turn the thermostat to the fan on/ cont position and the indoor fan operates. This action verifies that; - Solution The transformer is functioning. On most air-to-air heat pumps; - Solution The indoor and outdoor coils are the same size and physical capacity. A heat pump system, operating at 45°F ambient, may be _______ efficient than electric resistance heat - Solution 3 to 4 times more. Since electric resistance heat produces 1 watt of usable heat for each watt of energy purchased, electric resistance heat has a COP of; - Solution 1:1 As outdoor ambient air temperature decreases, a heat pump's COP; - Solution Decreases. During the defrost cycle, the system switches to the ___________ Mode. - Solution Cooling. During the heating mode, the refrigerant in the indoor coil is under; - Solution High pressure. What three things happen in most air-to-air heat pump during defrost? - Solution The reversing valve must switch to cooling mode, the outdoor fan shuts off and auxiliary heat is energized. High suction pressure and low discharge pressure on a heat pump system operating in either the heating or cooling mode can be an indication of; - Solution Compressor inefficiency. The preferred method to preform adjustments to the refirgerant charge in a heat pump system is in the ________ more. - Solution Cooling. You answer a service call for insufficient heat. You find the suction pressure is higher and discharge pressure is lower than normal. Using a digital thermometer, you measure the line entering the reversing valve from the compressor discharge and find 215°F. You then measure the line leaving the reversing valve that connects to the indoor coil and find 185°F. These readings are an indication of; - Solution A faulty reversing valve. The customer complaint is not enough heat. You install service gauges and find the low side pressure is higher than normal and the high side pressure is lower than normal. You switch to the cooling mode and find the pressures are normal. The most likely cause of the problem is; - Solution A stuck open check valve at the outdoor coil. A customer complains that their heat pump systems blows cool air periodically during the heat mode. This could be caused by; - Solution A faulty defrost relay (does not energized the aux. heat during the defrost mode.) When a heat pump is in the heating mode, which can cause frost accumulation on the outdoor coil when the ambient temperature is 45*F? - Solution The outdoor coil is colder than the ambient air. The indoor fan on a heat pump system operates; - Solution At the same speed for heating or cooling; The defrost cycle can be initiated by; - Solution Time and temperature. The defrost cycle can be terminated by; - Solution Time/temperature Movement of the piston in the reversing valve is accomplished by; - Solution Bleeding pressure from one side of the piston to the suction side of the compressor. Some close coupled (package unit) heat pumps use an electronic expansion valve is; - Solution Electronic expansion valves can meter refrigerant in either direction. Liquid line filter-driers that are used on heat pump system; - Solution Must be a bi-flow design if used without check valves. When installing the heat pump outdoor unit, care should be taken to provide for drainage during the ________ cycle. - Solution Defrost.