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and unoccupied periods. This scheduling function can be accessed
from the Equipment Touch display pad on the Schedules screen
(requires User password).
NOTE: All temperature related events have an additional 10-
second (fixed) delay on make to allow temperatures to settle.
Occupied Mode
•
When the program control source calls for the start of the
Occupied Mode, and the OEM controller has verified that
there are no fault or shutdown conditions, a 30-second
(fixed) delay timer begins.
•
After the delay time expires, the unit goes into Occupied
Mode and the following happens.
OUTDOOR AIR DAMPER (OD)
•
After the unit goes into Occupied Mode, the Outdoor Air
(OA) damper will open. As the OA damper opens, the OA
damper actuator (OADA) auxiliary switches close.
•
The OA damper stays open until the system reaches the
end of the Occupied Mode period. It will remain open until
the supply fan turns off. After the supply fan turns off, the
OA damper will close.
SUPPLY FAN (SF)
•
As the OA damper opens, the OADA auxiliary switch (ad-
justable) will close and the SF will turn on.
•
The SF shall operate continuously while the unit is in Oc-
cupied Mode. When the system reaches the end of the Oc-
cupied Mode period, the SF will continue to run for an ad-
ditional 2 minutes before turning off.
•
SF-VSC (Supply Fan with Variable Speed Control):
The SF-VSC will modulate its speed based on the SF Dif-
ferential Pressure Transmitter (SF-DPT) signal to maintain
the supply duct static pressure set point.
(Optional) For constant air volume (CAV), select "Manual
Override" in the Equipment Touch keypad and input the
required speed (%) as determined in the field by Test and
Balancing.
EXHAUST FAN (EF)
•At the same time the SF turns on, the EF will be enabled
to run.
•The EF shall be enabled to run continuously while the
unit is in Occupied Mode. When the system reaches the
end of the Occupied Mode period, the EF will be enabled
to run for an additional 2 minutes before turning off.
•EF-VSC (Exhaust Fan with Variable Speed Control)
The EF-VSC will modulate its speed based upon the EF-
DPT to maintain the building static pressure set point:
-If the EF-Differential Pressure Transmitter (EF-DPT)
signal is above the building static pressure set point, the
EF-VSC will modulate its speed based upon the EF-
DPT to maintain the set point. If the EF-DPT signal is
below the building static pressure set point, the EF will
modulate down to 0% (adjustable) speed.
-(Optional) For constant air volume (CAV), select "Man-
ual Override" in the Equipment Touch keypad and input
the required speed (%) as determined in the field by Test
and Balancing.
ZAT/SAT SET POINT RESET
•
ZAT/SAT Set Point Reset is selectable using the Equip-
ment Touch display pad or Building Automation System
(BAS) (default is "OFF").
•
As the ZAT goes above the ZAT cooling set point, the SAT
cooling set point will decrease by a ratio (adjustable) in or-
der to lower the ZAT. As the ZAT goes below the ZAT
cooling set point, the SAT cooling set point will increase
by a ratio (adjustable) in order to raise the ZAT. When the
ZAT equals the ZAT cooling set point, the SAT cooling set
point will return to the original value.
•
As the ZAT goes below the ZAT heating set point, the SAT
heating set point will increase by a ratio (adjustable) in or-
der to raise the ZAT. As the ZAT goes above the ZAT heat-
ing set point, the SAT heating set point will decrease by a
ratio (adjustable) in order to lower the ZAT. When the ZAT
equals the ZAT heating set point, the SAT heating set point
will return to the original value.
•
Example: A ZAT:SAT ratio of 1:3 means for every 1°F of
ZAT increase the SAT set point will decrease by 3°F; max-
imum -15°F (ZAT = 73°F, SAT = 69°F; ZAT = 74°F, SAT
= 66°F; ZAT = 75°F, SAT = 63°F; etc.).
ENERGY CONSERVATION WHEEL (ECW)
•
After the OA damper opens and the SF turns on, the ECW
turns on.
•
ECW Standard Operation:
- When the OAT is 3°F (adjustable) above or below the
RAT (return air temperature), the ECW will be on; oth-
erwise it is off.
•
ECW with On/Off Defrost:
- When the OAT is 3°F (adjustable) above or below the
RAT, the ECW will be on. It will be off if the OAT is
less than 3°F (adjustable) above or below the RAT or if
the WExAT is below 25°F (adjustable) to allow for
wheel defrosting. When the WExAT rises above 35°F
(adjustable), the wheel will turn back on.
•
ECW with VFD Controlled Defrost (WM-VFD):
- When the OAT is 3°F (adjustable) above or below the
RAT, the ECW will be on. It will be off if the OAT is
less than 3°F (adjustable) above or below the RAT. It
will decrease speed or stop as the WExAT goes below
25°F (adjustable) to allow for wheel defrosting. It will
start back up and increase speed when the WExAT rises
toward 25°F (adjustable) or more.
COOLING MODE
•
Cooling Mode is available when the Entering Coil Air
Temperature (ECAT) is above the ECAT cooling lower
limit (55°F, adjustable) and there is a demand for cooling.
•
When the Entering Coil Air Temperature (ECAT) is 1°F
(adjustable) or more above the Supply Air Temperature
(SAT) cooling set point (72°F, adjustable), compressor #1
turns on.
•
When the SAT is 2°F (adjustable) or more above the SAT
cooling set point (72°F, adjustable), compressor #2 turns
on — not less than 10 minutes (adjustable) after compres-
sor #1 turned on.
•
When the SAT is 2°F (adjustable) or more below the SAT
cooling set point (72°F, adjustable), compressor #2 turns off.
•
When the ECAT is 1°F (adjustable) or more below the
Supply Air Temperature (SAT) cooling set point (72°F, ad-
justable), compressor #1 turns off.
•
Optional: When enabled, if there is a call for 1st stage
cooling, 2nd stage cooling will be enabled after a 10-minute
(adjustable) delay. Both compressors modulate to maintain
the cooling set point. Default is OFF.
•
Compressor enabling logic includes a 5-minute (fixed)
minimum run-time and a 5-minute (fixed) minimum time-
off delay to prevent compressor short cycling.
•
Digital Compressor:
- The OEM controls the digital compressor through a
Digital Compressor Module (DCM). The DCM will
modulate capacity by rapidly loading and unloading the
digital compressor in 15 second intervals.
- The digital compressor will modulate based upon the
DX Leaving Air Temperature (DX LAT) sensor and set
point (55°F, adjustable).
- If the DX LAT drops to 38°F or less, the DCM will fix
the compressor at 20% (adjustable).
33
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