Johnson Controls
5513350-JTG-1018
123
Guide Specifications (Continued)
8.
Diagnostics -
Upon start-up of the unit controller,
it shall run through a self-diagnostic check to verify
proper operation and sequence loading. The rooftop
unit controller shall continually monitor all input and
output points to maintain proper operation. The unit
shall continue to operate in a trouble mode or shut
down as necessary to prevent an unsafe condition
for the building occupants or to prevent damage to
the equipment. In the event of a unit shutdown or
alarm, the operating conditions, date, and time shall
be stored in the shutdown history to facilitate service
and troubleshooting. A minimum of 10 error histories
shall be recorded.
9.
Compressor Capacity Modulation -
Staging of the
multiple fixed [fixed and variable] speed compres
-
sors shall be used to control refrigeration capacity.
Upon entering cooling mode from other modes, the
unit controller shall estimate the cooling requirement
and match it closely to the capacity in order to reduce
the time required to satisfy the cooling requirements.
After the initial calculation, the unit controller shall add
or reduce stage as necessary to establish a balance
between the unit capacity and the space cooling load.
10.
Demand Control Ventilation (DCV) [Optional] -
CO
2
sensors shall be connected to the unit. The unit
controller shall reset the minimum OA damper posi-
tion based on demand. DCV shall remain active as
long as the unit is in occupied mode. The unit control-
ler has built-in sequences for indoor CO
2
and com-
parative CO
2
.
11.
Smoke Detector [Optional] -
The supply [return]
[supply and return] smoke detector[s] shall be pro
-
vided with the unit. A smoke detector ON signal shall
shutdown the unit.
12.
Smoke Control Inputs -
The smoke control se
-
quences shall be available through BAS communica-
tion [and
hard wired
connections using BAS interface
board]. The smoke control sequences shall be used
whenever the smoke control binary inputs are turned
ON to remove, exhaust, or ventilate smoke, fumes, or
other airborne contaminates from the occupied space.
The unit controller shall include purge, pressuriza-
tion, and evacuation sequences of operation. Smoke
control inputs shall be assigned a higher priority over
smoke detector and shall override a smoke detector
shutdown.
13.
Twinning
enables control of multiple rooftop units
sharing a common supply duct. The control algorithm
shall provide independent logic unit control. The in-
dependent logic unit control system shall not require
switchover of primary logic in case of rooftop unit
failure. The unit shall provide quick response time,
shared data for sensors and setpoints, simple config
-
uration, and easy setup. Twinning configuration shall
be available through BACnet
®
. No additional control
or communication wiring shall be required.
14. The control shall be installed and tested at the fac-
tory where the equipment is assembled. The follow
-
ing controls features shall be available based on se-
lected unit options:
a.
The control shall use a wall sensor that has a
means of overriding the unoccupied mode for a
programmable amount of time.
b. The unoccupied override time shall be pro-
grammed in minutes up to 4 hours.
c. The control shall have a SA sensor as standard.
d. The control shall have a RA sensor as standard.
e. The control shall have an outside air temperature
(OAT) sensor as standard.
f. The control shall use the RA sensor in place of
the space sensor if the space sensor fails for any
reason.
g.
The control shall have a 365 day real time clock
(RTC).
h. The control shall have an occupancy schedule that
allows two different occupied schedules per day for
each of the seven days of the week individually.
i. The control shall have 20 holiday schedules,
each capable of 99 days. The control's holiday
schedules shall have a start time associated with
each schedule.
j. The control shall be capable of operating the
economizer using dry bulb, single enthalpy, or
dual enthalpy.
k.
The control shall have the ability to do demand
ventilation control using two CO
2
sensors.
l. The control shall have a programmable maxi-
mum OA
damper position for IAQ operation.