Goodman Mfg RT6100004R13 manual S-41AEP* & MBE WITH SINGLE STAGE CON DENSERS, Servicing

SERVICING

4.0 Heating Operation

On heat pump units, when the room thermostat set to the heating mode, the reversing valve is not energized. As long as the thermostat is set for heating, the reversing valve will be in the de-energized position for heating except during a defrost cycle. Some installations may use one or more outdoor thermostats to restrict the amount of electric heat that is available above a preset ambient temperature. Use of optional controls such as these can change the operation of the electric heaters during the heating mode. This sequence of operation does not cover those applications.

4.1On a demand for first stage heat with heat pump units, the room thermostat energizes “G” and “Y” and 24Vac is supplied to “Y” at the heat pump unit and the “G” terminal on the EBTDR board. The heat pump is turned on in the heating mode and the blower motor starts after a 7 second on delay.

4.2If the first stage heat demand cannot be satisfied by the heat pump, the temperature indoors will continue to drop. The room thermostat will then energize terminal “W2’ for second stage heat and 24Vac will be supplied to heat sequencer HR1 on the heater assembly.

4.3HR1 contacts M1 and M2 will close will close within 10 to 20 seconds and turn on heater element #1. At the same time, if the heater assembly contains a second heater element, HR1 will contain a second set of con- tacts, M3 and M4, which will close and turn on heater element #2. The blower motor is already on as a result of terminal “G” on the EBTDR board being energized for the first stage heat demand.

Note: If more than two heater elements are on the heater assembly, it will contain a second heat sequencer, HR2, which will control the 3rd and 4th heater elements if available. If the second stage heat demand, “W2” cannot be satisfied by the heat pump, the temperature indoors will continue to drop. The room thermostat will then energize “W3” and 24Vac will be supplied to HR2 on the heater assembly. When the “W3” demand is satisfied, the room thermostat will remove the 24Vac from HR2. The contacts on HR2 will open between 30 to 70 seconds and heater elements #3 and #4 will be turned off. On most digital/electronic thermostats, “W3” will remain energized until the first stage heat demand “Y” is satisfied and then the “G”, “Y”, “W2” and “W3” demands will be removed.

4.4As the temperature indoors increase, it will reach a point where the second stage heat demand, “W2”, is satisfied. When this happens, the room thermostat will remove the 24Vac from the coil of HR1. The contacts on HR1 will open between 30 to 70 seconds and turn off both heater element(s). The heat pump remains on along with the blower motor because the “Y” demand for first stage heat will still be present.

4.5When the first stage heat demand “Y” is satisfied, the room thermostat will remove the 24Vac from “G” and “Y”. The heat pump is turned off and the blower motor turns off after a 65 second off delay.

5.0 Defrost Operation

On heat pump units, when the room thermostat is set to the heating mode, the reversing valve is not energized. As long as the thermostat is set for heating, the reversing valve will be in the de-energized position for heating except during a defrost cycle.

5.1The heat pump will be on and operating in the heating mode as described the Heating Operation in section 4.

5.2The defrost control in the heat pump unit checks to see if a defrost is needed every 30, 60 or 90 minutes of heat pump operation depending on the selectable setting by monitoring the state of the defrost thermostat attached to the outdoor coil.

5.3If the temperature of the outdoor coil is low enough to cause the defrost thermostat to be closed when the defrost board checks it, the board will initiate a defrost cycle.

5.4When a defrost cycle is initiated, the contacts of the HVDR relay on the defrost board open and turns off the outdoor fan. The contacts of the LVDR relay on the defrost board closes and supplies 24Vac to “O” and “W2”. The reversing valve is energized and the contacts on HR1 close and turns on the electric heater(s). The unit will continue to run in this mode until the defrost cycle is completed.

5.5When the temperature of the outdoor coil rises high enough to causes the defrost thermostat to open, the defrost cycle will be terminated. If at the end of the programmed 10 minute override time the defrost thermo- stat is still closed, the defrost board will automatically terminate the defrost cycle.

5.6When the defrost cycle is terminated, the contacts of the HVDR relay will close to start the outdoor fan and the contacts of the LVDR relay will open and turn off the reversing valve and electric heater(s). The unit will now be back in a normal heating mode with a heat pump demand for heating as described in the Heating Operation in section 4.

S-41 AEP* & MBE WITH SINGLE STAGE CON-

DENSERS

AEP* & MBE ELECTRONIC BLOWER TIME DELAY RELAY

SEQUENCE OF OPERATION

This document covers the basic sequence of operation for a typical application with a mercury bulb thermostat. When a digital/electronic thermostat is used, the on/off staging of the auxiliary heat will vary. Refer to the installation instructions and wiring diagrams provided with the MBE for specific wiring connections, dip switch settings and system configuration.

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