Demand Defrost Control, Jumper, Minimum Time

Demand Defrost Control

The demand defrost board controls the defrost cycle in response to ambient temperature, outdoor coil temperature and accumulated compressor run time.The heat pump is allowed to operate in the heating mode until the combination of outdoor ambient and outdoor coil temperatures indicate that defrosting is necessary, based on the programmed defrost curve. There are four preprogrammed defrost curves on the board. A jumper pin is used to switch between the different curves. The factory default setting is program two. This is the recommended setting for most standard applications. For differences between the defrost curves, see Table 1.

The standard defrost cycle will terminate after 13 minutes and 39 seconds or when the coil temperature reaches its terminate temperature, whichever comes ﬁ rst.

The defrost board is equipped with a 5 minute Anti-Short Cycle Delay (ASCD).The compressor will not turn on until the minimum 5 minute off time is reached.

The control contains a forced - defrost feature, which puts the system into defrost mode every 6 hours and 4 minutes, unless the coil temperature is above the selected terminate temperature.

The system can be manually forced into defrost mode at any time by shorting the TEST terminals on the demand defrost board together for more than 9 seconds. The coil temperature sensor does not need to be cold when the unit is forced into defrost.After the TEST input is removed, the defrost mode will terminate in 13.7 minutes or when the coil temperature is above the terminate set-point or when the Y input is removed, whichever occurs ﬁ rst.

NOTE:If a demand curve is selected which has a 30 second compressor time delay in defrost, the delayis reduced to 10 seconds in TEST mode.

Jumper	Minimum Time	Terminate
Jumper	Between Defrosts	Terminate
Position	Between Defrosts	Temp(° F)
	(min)

1	20	40
2	20	40

3	20	32

4	20	75

Table 1. Demand Defrost Curve Proﬁles

Electric Heat Package (optional)

This heat pump is shipped without an auxiliary electric heat kit installed.If electric heat is desired, an accessory Heater Kit must be ﬁ eld installed. See Speciﬁcations Sheet for available kits and their application.

•Select the correct size heat package for the installation.

•Follow installation instructions provided with each heater kit.

•Installation is most easily accomplished before making duct or electrical connections.

•Refer to Table 4 (page 20) for blower speeds.

Thermostat Connections

•The Q5RF heat pump is a two stage cooling and heating appliance that requires a 2-stage Cooling/Heating thermostat. The heat-cool thermostat prevents simultaneous operation of the heating and cooling units and is equipped with an ON-AUTO fan mode that allows the home owner to operate the indoor blower when only air circulation is desired.

•The control circuit wiring must comply with the current provisions of the NEC (ANSI/NFPA 70) and with applicable local codes having jurisdiction. Thermostat connections should be made in accordance with the instructions supplied with the thermostat and the indoor equipment.

•The low voltage wires must be properly connected to the units low voltage terminal block.

1. Route 24V control wires through the sealing grommet (Figure 8, page 8) near the power entrance.

2. Connect the control wires to the defrost board and blower relay wire (Figure 10, page 11).

•Several thermostat options are available depending on the accessories installed with the unit. Select a thermostat that operates in conjunction with the installed accessories.

•The thermostat should be mounted about 5 feet above the ﬂ oor on an inside wall. DO NOT install the thermostat on an outside wall or any other location where its operation may be adversely affected by radiant heat from ﬁ replaces, sunlight, or lighting ﬁ xtures, and convective heat from warm air registers or electrical appliances. Refer to the thermostat manufacturer’s instruction sheet for detailed mounting information.