REF UNIT 43

Question 1

(43.1) What is responsible for the heat pump’s ability to reverse the direction of refrigerant flow?

Answer 1

the four-way reversing valve

Question 2

(43.2) what does a water-to-air heat pump mean?

Answer 2

it uses water to heat air.

Question 3

(43.3) what does it mean when a heat pump “fails in heating?”

Answer 3

when the solenoid is de-energized, the refrigerant will flow from the compressor into the indoor unit.

Question 4

(43.3) what is a direct-acting four-way reversing valve and where are they used?

Answer 4

a reversing valve that moves by direct force from the solenoid. They’re found in small heat pumps.

Question 5

(43.3) where are pilot-operated reversing valves found?

Answer 5

in larger heat pumps.

Question 6

(43.5) what are the names of the 2 lines in a heat pump?

Answer 6

gas line and liquid line

Question 7

(43.6) in a heat pump, two metering devices are used. what stops the refrigerant for going through the unintended metering device?

Answer 7

a check valve

Question 8

(43.6) what kind of TXVs are used in heat pumps?

Answer 8

vapor charged TXVs

Question 9

(43.6) what are the TXV’s with built in check valves called?

Answer 9

bidirectional thermostatic expansion valves

Question 10

(43.6) T or F: in old cap tube heat pumps, two cap tubes are used, one for heating and one for cooling.

Answer 10

true

Question 11

(43.6) T or F: heat pumps that use an EEV only need one

Answer 11

true

Question 12

(T or F) heat pumps that use a piston metering device only need one.

Answer 12

false

Question 13

(43.6) why would a heat pump system use a cap tube in the indoor coil and a TXV in the outdoor?

Answer 13

the cap tube is used in summer as the conditions are somewhat constant, and the TXV is used in winter where the conditions vary.

Question 14

(43.8) what are the three possible sources of auxiliary heat that a heat pump could have?

Answer 14

electric, gas, or oil.

Question 15

(43.8) define balance point in heatpumps

Answer 15

the lowest ambient temperature that a heat pump will pump the exact same amount of heat that the structure is leaking.

Question 16

(43.9) why is COP so high in heat pumps?

Answer 16

because the total effect isn’t the NRE, but the THOR, which is more that NRE.

Question 17

(43.10) in a furnace with a coil, why Is the coil placed before the auxiliary heating in the airstream?

Answer 17

so that the auxiliary heat doesn’t heat the coil too much and cause damage.

Question 18

(43.10) what is a cold wall?

Answer 18

the wall close to outside. So when a ducted system is heating, the wall it’s closest too will be warm, and the walls closest away will feel cold as a result.

Question 19

(43.12) what are heat anticipators?

Answer 19

devices used in space thermostats to reduce temperature swing.

Question 20

(43.12) T or F: there are two anticipators in a space thermostat with 2nd stage heating, and only one in single stage heating.

Answer 20

true

Question 21

(43.13) define time and temperature initiated defrost?

Answer 21

exactly what it sounds like. it uses a temperature sensor or air pressure switch on the coil

Question 22

(43.13) what is the normal defrost termination temperature on a heat pump?

Answer 22

50°F

Question 23

(44.2) define open-loop and closed-loop geothermal heat pumps.

Answer 23

open-loops are water source, closed-loop are earth-coupled.