Architect and Engineering Manual

6
FEATURES & BENEFITS
HEAT PUMP OPERATION
Heat pumps save money compared to electric
resistance heat, but if the unit cannot provide room
occupant comfort, the savings may be of questionable
benefit. GE Appliances has years of experience with
designing Zoneline® heat pumps to solve the problem
of guest complaints.
The heat pump unit uses a two-stage heat/one-stage
cooling thermostat. Stage one, heat pump operation,
will operate as specified by the remote thermostat being
used as long as outdoor conditions will allow. If the
remote thermostat asks for heat pump heating outside
of unit heat pump operating conditions, the heating
request will be met by utilizing back-up resistance heat.
The Z oneline Vertical chassis will operate in efficient heat
pump mode down to a 25°F outdoor temperature.
At temperatures below this, the unit will automatically
switch to electric heat.
The resistance heater and the heat pump do not operate
simultaneously.
HEAT PUMP LOGIC
The chart below indicates the standard heating source
of the AZ95 series heat pump models under various
outdoor conditions. The unit is designed to provide
heat pump savings without sacrificing room comfort.
QUICK HEAT RECOVERY
Unit software will provide electric resistance heating
as the first heat cycle following the unit having been
set to either off or cool on the remote thermostat. This
ensures occupant comfort by quickly reaching the desired
setpoint temperature. All subsequent heating cycles will
follow heat staging as dictated by the remote thermostat
if required outdoor temperature conditions are met. Quick
heat recovery is not influenced by heat pump logic.
HEAT PUMP DEFROST
Zoneline heat pumps utilize a reverse-cycle, demand-
defrost system to extend heat pump operation and
increase savings from extended operation. The
microprocessor determines the need for defrosting from
criteria based on continuous compressor running time,
outdoor air temperature and outdoor coil temperature.
When defrosting is required, the unit reverses the flow
of refrigerant to direct the hot gas into the outdoor coil
to melt the frost buildup.
Before and after the reverse-cycle defrost, the unit shuts
off the compressor to allow the refrigerant pressures to
equalize through the system. During these periods of
pressure equalization, the full resistance heat capacity
of the unit is activated to help ensure room comfort
conditions during the defrost cycle. The unit remains in
the defrost cycle for a minimum of three minutes and
up to a maximum of nine minutes. The defrost cycle
terminates when the outdoor coil reaches a temperature
of 68
o
F or the maximum time has been reached.
BOOST HEAT
The AZ95 series offers a Boost Heat option feature that
utilizes partial supplemental resistance heat at the same
time as the heat pump operation. The Boost Heat feature
changes stage one heating (heat pump) to be heat pump
with partial resistance heat. Stage two heating stays as full
resistance heat.
NOTE: Heat Pump and full resistance heat shall never be
on at the same time.
ELECTRONIC CONTROL DIAGNOSTICS/
SERVICE MODE
The Zoneline Vertical system continuously monitors
the unit operation and in some cases the unit may take
action and shut down until conditions are corrected.
The electronic control will store/provide Error Codes
to aid in diagnosis and correction to get the unit up
and running quickly.
In addition to Error Codes, the unit is equipped with
Service Modes that allow for independent testing of unit
functionality. This allows for fan, heat, cool operations
among other checks to be “forced" without signals from
the remote thermostat or unit temperature sensors. This
is a valuable tool that helps pinpoint operational problems
and also helps distinguish unit malfunction from problems
caused by remote thermostat.
See the product Use & Care/Mini-Manual for specifics on
Error Codes, Service Modes, and how to use the system.
Heat Setting Configuration
All-Electric
Heat Mode
(Aux Mode 8)
He
at Boost
Mode
(Aux Mode 9)
Full Resistance
Heat
Full Resistance
Heat
Full Resistance
Heat
Full Resistance
Heat
Full Resistance
Heat
Full Resistance
Heat
Full Resistance
Heat
Between 85
o
F
and 25
o
F
Heat Pump
Above 85
o
F
OFF
OFF
ON
OFF
ON
OFF/ON
Below 25
o
F
Heat Pump +
Supplemental
Heater*
Outdoor Temperature
Preliminary specifications. Subject to change.
*Simultaneous supplemental heat (Boost Heat): 1.0kW @ 230V & 265V;
0.8kW @ 208V
Conditions are representative of unit response but not intended for
minimum rated ambient conditions