EMI T2HA, S2HA Multi-Zonecondenser Sequence Of Operation, Cooling operation, Multi-zoneHeat, Pump

MULTI-ZONE CONDENSER SEQUENCE OF OPERATION

EMI America Series multi-zone heat pump	Heat pump condensers utilize a reversing
condensers are designed to operate with	valve to provide reverse cycle operation.
EMI America Series indoor air handlers.	Therefore the outdoor unit will act as ei-
Both the condenser (outdoor unit) and	ther a condenser or an evaporator there-
evaporator (indoor unit) have a high Volt	by providing comfort cooling or heating to
service connection. Each is to be indepen-	the indoor space. The reversing valve is
dently connected to the electrical service	energized in cooling. Should the valve fail
panel. (See the unit name plate for the cor-	to actuate, the system will default to the
rect breaker type and size). The outdoor	heating mode of operation.
and indoor units are also connected to each
other through a low Volt interconnect wiring.	Cooling operation, Multi-zone Heat
A 24V transformer located in the indoor unit	Pump:
provides the low Volt power source.	Cooling mode operation requires that the
The S & T series (S2HA, T2HA, T3HA &	control (either unit mount or remote wall
	mount thermostat) make a connection be-
T4HA) is a limited range heat pumps that
	tween low-Volt terminals “R” and “Y” along
will provide comfort cooling or heat pump
	with “R” and “O”. When the indoor control
operation operate at an outdoor tempera-
	is placed in cooling mode, with the set point
ture range between 35°F and 115°F for
	temperature below the room temperature,
cooling, 35°F and 75°F for (heat pump)
	the reversing valve will energize (R & O)
heating. The outdoor unit is equipped
	along with the compressor and outdoor fan
with a thermostat that will switch off the
	(R & Y). When the indoor control is satis-
condenser when temperature falls below
	fied and the room temperature falls below
35°F. For heat pump mode the condenser
	the set temperature, the compressor and
operation will cease and then switch on
	fan will de-energize. The EMI indoor unit
the indoor electric heat. For cooling mode,
	is equipped with an anti-short cycle timer
condenser operation will cease.
	(ASCT) will prevent the compressor from
The S & T series (S2HA, T2HA, T3HA &	re-starting for three minutes.
T4HA) limited range heat pump condens-	When the outdoor temperature falls below
ers are designed to operate as a single
	35°F, compressor operation will cease.
stage cooling, two stage heating unit. For
full operation the unit should be matched	Heating operation, Multi-zone Heat
with an appropriate EMI indoor unit with
	Pump:
electric heat and unit mounted controls or
	Heating mode operation requires that the
a wall mounted thermostat.
	control (either unit mount or remote wall
For two stage heating operation the indoor	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-
	perature above room temperature, the
unit on the selection of the proper thermo-	compressor and outdoor fan (R & Y) will
stat for the system.	energize. When the indoor control is satis-
Condenser Operation:	fied and the room temperature rises above
	the set temperature, the compressor and
The transformer located in the indoor unit	fan will de-energize. The EMI indoor unit
provides 24V, low-Volt control power to the	is equipped with an anti-short cycle timer
condenser (outdoor unit). This can be mea-	(ASCT) will prevent the compressor from
sured across low-Volt terminals “R” and “C”.	re-starting for three minutes.

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