EMI EMI Corp manual Multi-Zonecondenser Sequence Of Operation, Condenser Operation

MULTI-ZONE CONDENSER SEQUENCE OF OPERATION

EMI America Series multi-zone heat pump condensers are designed to operate with EMI America Series indoor air handlers. Both the condenser (outdoor unit) and evaporator (indoor unit) have a high Volt service connection. Each is to be indepen- dently connected to the electrical service panel. (See the unit name plate for the cor- rect breaker type and size). The outdoor and indoor units are also connected to each other through a low Volt interconnect wiring. A 24V transformer located in the indoor unit provides the low Volt power source.

The S2HA is a limited range heat pump that will provide comfort cooling or heat pump operation operate at an outdoor tem- perature range between 35°F and 115°F for cooling, 35°F and 75°F for (heat pump) heating. The outdoor unit is equipped with a thermostat that will switch off the condenser when temperature falls below 35°F. For heat pump mode the condenser operation will cease and then switch on the indoor electric heat. For cooling mode, condenser operation will cease.

The S2HA limited range heat pump con- densers are designed to operate as a single stage cooling, two stage heating unit. For full operation the unit should be matched with an appropriate EMI indoor unit with electric heat and unit mounted controls or a wall mounted thermostat.

For two stage heating operation the indoor unit must be equipped with an electric strip heater.

See the instruction manual for the indoor unit on the selection of the proper thermo- stat for the system.

Condenser Operation:

The transformer located in the indoor unit provides 24V, low-Volt control power to the condenser (outdoor unit). This can be measured across low-Volt terminals “R” and “C”.

Heat pump condensers utilize a reversing valve to provide reverse cycle operation. Therefore the outdoor unit will act as ei- ther a condenser or an evaporator there- by providing comfort cooling or heating to the indoor space. The reversing valve is energized in cooling. Should the valve fail to actuate, the system will default to the heating mode of operation.

Cooling operation, Multi-zone Heat Pump:

Cooling mode operation requires that the control (either unit mount or remote wall mount thermostat) make a connection be- tween low-Volt terminals “R” and “Y” along with “R” and “O”. When the indoor control is placed in cooling mode, with the set point temperature below the room temperature, the reversing valve will energize (R & O) along with the compressor and outdoor fan (R & Y). When the indoor control is satis- fied and the room temperature falls below the set temperature, the compressor and fan will de-energize. The EMI indoor unit is equipped with an anti-short cycle timer (ASCT) will prevent the compressor from re-starting for three minutes.

When the outdoor temperature falls below 35°F, compressor operation will cease.

Heating operation, Multi-zone Heat Pump:

Heating mode operation requires that the control (either unit mount or remote wall mount thermostat) make a connection between low-Volt terminals “R” and “Y” only. When the indoor control is placed in heating mode, with the set point tem- perature above room temperature, the compressor and outdoor fan (R & Y) will energize. When the indoor control is satis- fied and the room temperature rises above the set temperature, the compressor and fan will de-energize. The EMI indoor unit is equipped with an anti-short cycle timer (ASCT) will prevent the compressor from re-starting for three minutes.

Multi-zone Heat Pump Condensing Units 16 www.enviromaster.com