Ducane (HVAC) 2HP13 warranty System Operation

10.Remove charge if superheat is low and add charge if superheat is high.

Model	Required Subcooling
		(± I/F)
	HP 13		HP 14
18	14		10
24	9		3
30	13		8
36	9		14
42	11		3
48	8		9
60	12		-

Units with Indoor TXV

Units installed with TXV on indoor side, require charging with the subcooling method.

1.Operate unit a minimum of 10 minutes before checking charge.

2.Measure liquid service valve pressure by attaching an accurate gage to service port. Determine saturation temp. from T/P chart.

3.Measure liquid line temperature by attaching an accurate thermistor type or electronic thermometer to liquid line near outdoor coil.

4.Calculate subcooling (saturation temp.— measured temp.).

5.Find the point where required subcooling temperature intersects measured liquid service valve pressure.

6.Add refrigerant if subcooling is lower than table below. Recover refrigerant if subcooling is high.

Heating Check Chart Procedure

To check system operation during heating cycle, refer to the Heating Check Chart located on back of control box cover. This chart indicates whether a correct relationship exists between system operating pressure and air temperature entering indoor and outdoor units. If pressure and temperature do not match on chart, system refrigerant charge may not be correct. Do not use chart to adjust refrigerant charge.

Charge must be rechecked again during the cooling season.

Cold Weather Application

A cold weather accessory kit may be required for heat pumps operating at ambient conditions below 25/ F. Supplemental heat should be provided for these conditions due to the expected performance degeneration.

SYSTEM OPERATION

The outdoor unit and indoor blower cycle on demand from the room thermostat. When the thermostat blower switch is in the ON position, the indoor blower operates continuously.

Filter Drier

The outdoor unit is equipped with a bi-flow filter drier. If replacement is necessary, order new dryer according to the service parts manual.

Emergency Heat Function (Room Thermostat)

An emergency heat function is designed into some room thermostats. This feature is applicable when isolation of outdoor unit is required or when auxiliary electric heat is staged by outdoor thermostats. When the room thermostat is placed in the emergency heat position, the outdoor unit control circuit is isolated from power and field-provided relays bypass the outdoor thermostats. An amber indicating light simultaneously comes on to remind the homeowner that he is operating in the emergency heat mode.

Emergency heat is usually used during an outdoor unit shutdown, but it should also be used following a power outage. If power has been off for over an hour and the outdoor temperature is below 50/F (10/C). System should be left in the emergency heat mode at least six hours to allow the crankcase heater sufficient time to prevent compressor slugging. This applies only to systems with crank case heaters.

Defrost System

The defrost system includes two (2) components: a defrost thermostat and a defrost control.

Defrost Thermostat

The defrost thermostat is located on the liquid line between the check/expansion valve and the distributor. When defrost thermostat senses 29/F or cooler, the thermostat contacts close and send a signal to the defrost control board to start the defrost timing. It also terminates defrost when the liquid line warms up to 60/F.

Defrost Control

The defrost control board includes the combined functions of a time/temperature defrost control, defrost relay, diagnostic LEDs and terminal strip for field wiring connections.

The control provides automatic switching from normal heating operation to defrost mode and back. During compressor cycle, the control accumulates compressor run times at 30-, 60-, or 90-minute field-adjustable intervals. If the defrost thermostat is closed when the selected compressor run time interval ends (call for

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