20
Table 7 —
Economizer Module - Left Hand Terminal
Blocks
Table 8 —
Economizer Module - Right Hand Terminal
Blocks
Timeout and Screen Saver
When no buttons have been pressed for 10 minutes, the LCD
displays a screen saver, which cycles through the Status items.
Each status item displays in turn and cycles to the next item after
5 seconds.
HH79AH001 Dry Bulb Sensor
Economizers are shipped standard with an HH79AH001 outside
air dry bulb sensor (see Fig. 34). System default setting (high
temp limit) is 63°F, and has a range of 48°F to 80°F. The sensor is
factory installed on the economizer.
NOTE: A second HH79AH001 sensor is provided for mixed
air temperature.
Fig. 34 —
HH79AH001 Dry Bulb and Mixed Air Sensor
NOTE: California high temperature setting requirements by
region are shown below in Table 9.
Table 9 —
California Title 24 Regional High Limit Dry
Bulb Temperature Settings
*
Only the high limit control devices listed are allowed to be used and at the
setpoints listed. Others such as Dew Point, Fixed Enthalpy, Electronic Enthalpy,
and Differential Enthalpy Controls, may not be used in any climate zone for
compliance with Section 140.4(e)1 unless approval for use is provided by the
Energy Commission Executive Director.
†
At altitudes substantially different than sea level, the Fixed Enthalpy limit value
shall be set to the enthalpy value at 75°F and 50% relative humidity. As an
example, at approximately 6,000 foot elevation, the fixed enthalpy limit is approxi-
mately 30.7 Btu/lb.
Enthalpy Settings (Enthalpy Optional)
If installing the optional HH57AC081 enthalpy sensor. The
HH79AH001 dry bulb outside air sensor must first be removed.
Wire enthalpy to S-BUS connections on W7220 controller
through (2) gray wires.
When the OA temperature, enthalpy and dew point are below the
respective setpoints, the outdoor air can be used for economizing.
Figure 35 shows the new single enthalpy boundaries in the
W7220. There are 5 boundaries (setpoints ES1 through ES5),
which are defined by dry bulb temperature, enthalpy and dew
point.
See Table 10 for ENTH CURVE setpoint values.
To use enthalpy the W7220 must have a HH57AC081 enthalpy
control sensor for OA. The W7220 calculates the enthalpy and
dewpoint using the OA temperature and humidity input from the
OA sensor. When the OA temperature, OA humidity and OA dew
point are all below the selected boundary, the economizer sets the
economizing mode to YES, economizing is available.
When all of the OA conditions are above the selected boundary,
the conditions are not good to economize and the mode is set to
NO. If using OA enthalpy sensor option, remove and discard the
dry bulb sensor shipped with the economizer. System default
setting is ES3 enthalpy curve. See Table 9 for California Title 24
high limit dry bulb temperature settings.
Figure 35 shows the 5 current boundaries. There is also a high
limit boundary for differential enthalpy. The high limit boundary
is ES1 when there are no stages of mechanical cooling energized
and HL (high limit) when a compressor stage is energized.
Table 10 provided the values for each boundary limit.
LABEL
TYPE
DESCRIPTION
Top Left Terminal Block
MAT
MAT
20k NTC
and COM
Mixed Air Temperature Sensor (Polarity
Insensitive Connection)
OAT
OAT
20k NTC
and COM
Outdoor Air Temperature Sensor (Polarity
Insensitive Connection)
S-BUS
S-BUS
S-BUS
(Sylk Bus)
Enthalpy Control Sensor
(Polarity Insensitive Connection)
Bottom Left Terminal Block
IAQ 2-10
2-10 vdc
Air Quality Sensor Input (e.g. CO
2
sensor)
IAQ COM
COM
Air Quality Sensor Common
IAQ 24V
24 vac
Air Quality Sensor 24 vac Source
ACT 2-10
2-10 vdc
Damper Actuator Output (2-10 vdc)
ACT COM
COM
Damper Actuator Output Common
ACT 24v
24 vac
Damper Actuator 24 vac Source
LABEL
TYPE
DESCRIPTION
Top Right Terminal Blocks
AUX2 I
24 vac IN
The first terminal is not used.
OCC
24 vac IN
Shut Down (SD) or HEAT (W)
Conventional only
and
Heat Pump Changeover (O-B) in Heat
Pump mode.
E-GND
E-GND
Occupied/Unoccupied Input
EXH1
24 vac OUT Exhaust Fan 1 Output
AUX1 O
24 vac OUT
Programmable:
Exhaust fan 2 output
or
ERV
or
System alarm output
Bottom Right Terminal Blocks
Y2-I
24 vac IN
Y2 in - Cooling Stage 2 Input from space
thermostat
Y2-O
24 vac OUT Y2 out - Cooling Stage 2 Output to stage
2 mechanical cooling
Y1-I
24 vac IN
Y1 in - Cooling Stage 2 Input from space
thermostat
Y1-O
24 vac OUT Y1 out - Cooling Stage 2 Output to stage
2 mechanical cooling
C
COM
24 vac Common
R
24 vac
24 vac Power (hot)
DEVICE TYPE*
CLIMATE
ZONES
REQUIRED HIGH LIMIT
(ECONOMIZER OFF
WHEN):
DESCRIPTION
FIXED DRY BULB
1, 3, 5, 11-16
OAT exceeds 75°F
2, 4, 10
OAT exceeds 73°F
6, 8, 9
OAT exceeds 71°F
7
OAT exceeds 69°F
DIFFERENTIAL DRY
BULB
1, 3, 5, 11-16
OAT exceeds RA Temp.
2, 4, 10
OAT exceeds -2°F
6, 8, 9
OAT exceeds -4°F
7
OAT exceeds -4°F
FIXED ENTHALPY†
+ FIXED DRY BULB
ALL
OAT exceeds 28 Btu/lb of
dry air or OAT exceeds 75°F
Honeywell
HH79AH001
