HVAC Test 2 (week 7)

"Demand Defrost" is terminated by:

• Temperature

• Time

• Pressure

• Weight of the Ice on the coil

What is used to remove the ice from a heat pump in the winter?

• high temperature refrigerant from the compressor cycling through the indoor coil

• electric heat strips

• low temperature refrigerant from the compressor cycling through the outdoor coil

Defrosting an outdoor coil in the winter time is a normal operation and does not affect the overall efficiency of a heat pump.

• True

• False

The temperature switch for the Defrost cycle will Close at:The temperature switch for the Defrost cycle will Close at:

• 45°F

• 32°F

• 50°F

• 26°F

The Temperature Sensor/Switch for the the Defrost Cycle is _____________ switch.

• Normally Closed (NC)

• Normally Open (NO)

It is common for the outdoor unit to ice-up when the heat pump is operated in the heat mode.

• True

• False

When the heat pump goes into Defrost, the Reversing Valve is switched into the cooling mode by:

• the Transformer

• the Thermostat

• the Defrost Relay/Board

• the Compressor Contactor

The defrost cycle is terminated when

• The unit has operated in defrost for 10 minutes OR the outdoor coil has warmed to 50°F

• The unit has operated in defrost for 10 seconds OR the outdoor coil has warmed to 26°F

• The unit has operated in defrost for 10 seconds OR the outdoor coil has warmed to 40°F

• The unit has operated in defrost for 10 minutes AND the outdoor coil has warmed to 45°F

What prevents cold air from being circulated to the heated space during the defrost cycle?

• The auxiliary heater turns on to "temper" the air

• The indoor fan motor turns of

• The outdoor fan motor turns off

• Both a and b are correct

The Maximum time the unit will operate in the Defrost Cycle is __________.

• 60 minutes

• 30 minutes

• 90 minutes

• 10 minutes