EMI T4HB, T3HB Multi-zoneCondenser Sequence of Operation, Cooling operation, Multi-zoneHeat, Pump

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Multi-zone Condenser Sequence of Operation

EMI America Series multi-zone heat	by providing comfort cooling or heating to
pump condensers are designed to operate	the indoor space. The reversing valve is
with EMI America Series indoor air han-	energized in cooling. Should the valve fail
dlers. Both the condenser (outdoor unit)	to actuate, the system will default to the
and evaporator (indoor unit) have a high	heating mode of operation.
Volt service connection. Each is to be inde-
pendently connected to the electrical ser-	Cooling operation, Multi-zone Heat
vice panel. (See the unit name plate for the	Pump:
correct breaker type and size). The outdoor	Cooling mode operation requires that the
and indoor units are also connected to each	control (either unit mount or remote wall
other through a low Volt interconnect wiring.	mount thermostat) make a connection be-
A 24v transformer located in the indoor unit	tween low-Volt terminals “R” and “Y” along
provides the low Volt power source.	with “R” and “O”. When the indoor control
The S & T series (S2HB, T2HB, T3HB &	is placed in cooling mode, with the set point
	temperature below the room temperature,
T4HB) heat pumps will provide comfort	the reversing valve will energize (R & O)
cooling or heat pump operation operate	along with the compressor and outdoor fan
at an outdoor temperature range between	(R & Y). When the indoor control is satis-
35°F and 115°F for cooling, 0°F and 75°F	fied and the room temperature falls below
for (heat pump) heating.	the set temperature, the compressor and
The S & T series (S2HB, T2HB, T3HB	fan will de-energize. The EMI indoor unit
& T4HB) heat pump condensers are de-	is equipped with an anti-short cycle timer
signed to operate as a single stage cool-	(ASCT) will prevent the compressor from
ing, two stage heating unit. For full opera-	re-starting for three minutes.
tion the unit should be matched with an
appropriate EMI indoor unit with electric	Heating operation, Multi-zone Heat
heat and unit mounted controls or a wall	Pump:
mounted thermostat.	Heating mode operation requires that the
For two stage heating operation the indoor	control (either unit mount or remote wall
	mount thermostat) make a	connection
unit must be equipped with an electric strip
	between low-Volt terminals	“R” and “Y”
heater.
	only. When the indoor control is placed
See the instruction manual for the indoor	in heating mode, with the set point tem-
unit on the selection of the proper thermo-	perature above room temperature, the
stat for the system.	compressor and outdoor fan (R & Y) will
	energize. When the indoor control is satis-
Condenser Operation:	fied and the room temperature rises above
The transformer located in the indoor unit	the set temperature, the compressor and
provides 24V, low-Volt control power to the	fan will de-energize. The EMI indoor unit
condenser (outdoor unit). This can be mea-	is equipped with an anti-short cycle timer
sured across low-Volt terminals “R” and “C”.	(ASCT) will prevent the compressor from
	re-starting for three minutes.
Heat pump condensers utilize a reversing	Note: For full operation the indoor unit
valve to provide reverse cycle operation.
Therefore the outdoor unit will act as ei-	must have an electric heater.

ther a condenser or an evaporator there-

Multi-zone Heat Pump Condensing Units 20