AAON HB-005 - Manual (Page 17)

17
2 Step Compressor Cooling Models
− The HB models with a 2 step cooling compressor
may use a 2 step cooling thermostat with the R, G,
Y1, Y2 & W terminals connected to the similarly
labeled terminals on the Control Board in the HB
unit.
− These HB models can also be connected to a
single step cooling thermostat with the Y terminal
on the thermostat connected to the Y2 terminal on
the Control Board in the HB unit. A built-in time
delay in the Control Board will cycle the 2 stages
of cooling as required.
Multiple Stage Heating
− HB models with 2 or 3 stage heating should have
the W1, W2 and W3 terminals on the thermostat
connected to the similarly labeled terminals on the
Control Board in the HB unit.
− These models can also be connected to a single
step heating thermostat with the W terminal on the
thermostat connected to the W2 terminal on the
Control Board in the HB unit for 2 step heating or
the W3 terminal for 3 step heating. A built-in time
delay in the Control Board will cycle the stages of
heating as required.
Programmable Thermostats
If a programmable thermostat be used, then the C
terminal on the thermostat should be connected to the
C or GND terminal on the Control Board.
Economizer Option
The economizer option is used to provide cooling at
lower outdoor air temperatures and to provide a
quantity of ventilation air to the occupied space. The
economizer option can be selected with either a
sensible outdoor air temperature sensor or an enthalpy
sensor that measures the heat content in the outdoor
air. The economizer controller can be field installed or
factory installed by AAON as selected by the
customer.
Supply Air Temperature Sensor
A supply air temperature sensor is factory wired and
provided within the equipment at the end of a coil of
wire. This sensor must be installed in the downstream
supply air ductwork at a sufficient distance from the
equipment to provide a correctly mixed supply air
temperature back to the unit control board.
Factory Installed
When factory installed the control board will use the
outdoor air sensor and the cooling signal from the
thermostat to provide a first stage of cooling using the
outside air when possible before starting the
compressor and mechanical cooling cycle. The
thermostat wiring to the control board with single or
multi-stages should be wired as listed previously.
Field Installed
When the control is field installed the 2 to 10 VDC
signal for the economizer damper motor must be wired
to the Control Circuit Board in the HB unit. See Figure
18a. Note that the jumper must be moved to the
“external” position and the signal wired to the ECONO
POS and GND terminals on the control board.
Return Air Bypass Option
The Return Air Bypass option is used to provide
additional moisture removal capacity to the HB unit.
For this application a humidistat must also be installed
in the conditioned space to provide a signal to initiate
the dehumidification. The humidistat may be
purchased from AAON or from others.
A return air bypass control system by others may be
field installed as selected by the customer instead of
factory installed by AAON.
Factory Installed
The control board in the HB unit must be wired to the
humidistat in the occupied space at the R and RH
terminals. The thermostat wiring to the control board
with single or multi-stages should be installed as listed
previously.
When the Humidistat is calling for moisture removal
from the occupied space, the compressor will operate
with the return air bypass damper in the open position
and the supply fan running in the low speed mode. If
the Thermostat calls for cooling, the bypass damper
will close and the fan will operate at high speed until
the thermostat is satisfied.
Field Installed
When the control is field installed, the 0 to 10 VDC
signal for the return air bypass damper motor must be
wired to the Control Circuit Board in the HB unit. See
Figure 16a. Note that the jumper must be moved to
the “external” position and the signal wired to the RAB
and GND terminals on the control board.