349687-JTG-A-1007
Johnson Controls Unitary Products
39
a.
Primary and auxiliary high-temperature limit switches.
b.
Induced draft motor speed sensor.
c.
Flame roll out switch (automatic reset).
d.
Flame proving controls. Unit shall have two inde-
pendent stages of capacity.
ELECTRIC HEATING (J**DJC/E MODELS)
Nickel chromium electric heating elements shall be provided
as required by the application with 1 or 2 stage control, as
required, from 13.5 KW to 72 KW capacities. The heating
section shall have a primary limit control(s) and automatic
reset to prevent the heating element system from operating
at an excessive temperature. Units with Electric Heating shall
be wired for a single point power supply with branch circuit
fusing (where required).
UNIT OPERATING CHARACTERISTICS
Unit shall be capable of starting and running at 125° F
outdoor temperature, exceeding maximum load criteria of
ARI Standard 340/360. The compressor, with standard
controls, shall be capable of operation down to 25° F outdoor
temperature. Accessory low ambient kit shall be available for
operation to 0° F. Unit shall be provided with fan time delay to
prevent cold air delivery before heat exchanger warms up
(Gas heat only).
ELECTRICAL REQUIREMENTS
All unit power wiring shall enter unit cabinet at a single factory
provided location and be capable of side or bottom entry, to
minimize roof penetrations and avoid unit field modifications.
Separate side and bottom openings shall be provided for the
control wiring.
STANDARD LIMITED WARRANTIES
•
Compressor 5 Years
•
Heat Exchanger 10 Years
•
Electric Heat Element 5 Years
•
Other Parts 1 Year
OPTIONAL OUTDOOR AIR
(Shall be made available by
either/or):
•
ELECTRONIC ENTHALPY AUTOMATIC ECONO-
MIZER
- Outdoor and return air dampers that are inter-
locked and positioned by a fully-modulating, spring-
return damper actuator. The maximum leakage rate for
the outdoor air intake dampers shall not exceed 2%
when dampers are fully closed and operating against a
pressure differential of 0.5 IWG. A unit-mounted potenti-
ometer shall be provided to adjust the outdoor and return
air damper assembly to take in CFM of outdoor air to
meet the minimum ventilation requirement of the condi-
tioned space during normal operation. During econo-
mizer operation, a mixed-air temperature control shall
modulate the outdoor and return air damper assembly to
prevent the supply air temperature from dropping below
55°F. Changeover from compressor to economizer oper-
ation shall be provided by an integral electronic enthalpy
control that feeds input into the basic module. The out-
door intake opening shall be covered with a rain hood
that matches the exterior of the unit. Water eliminator/fil-
ters shall be provided. Simultaneous economizer/com-
pressor operation is also possible. Dampers shall fully
close on power loss.
•
BAS-READY ECONOMIZER
- Outdoor and return air
dampers that are interlocked and positioned by a fully-
modulating, spring return damper actuator. The maxi-
mum leakage rate for the outdoor air intake dampers
shall not exceed 2% when dampers are fully closed and
operating against a pressure differential of 0.5 IWG.
For units with optional VAV control, free-cooling shall be
available while the outdoor dry bulb temperature (OAT)
remains below a programmable set-point of the control-
ler. Field-installed humidity sensors for either outdoor air
or outdoor & return air streams are available to provide
free-cooling based on single-enthalpy or dual-enthalpy
configurations, respectively. If free-cooling is available, a
call for cooling shall modulate the economizer in order to
maintain a supply air temperature (SAT) programmable
set-point. With the use of a field-installed indoor air qual-
ity sensor, the controller shall provide Demand Ventila-
tion by modulating the economizer dampers to allow
more outside airflow upon detection of elevated indoor
CO2 concentrations above a programmable set-point.
With an additional field-installed outdoor air quality sen-
sor, Differential Demand Ventilation shall be provided.
The outdoor intake opening shall be covered with a rain
hood that matches the exterior of the unit. Water elimina-
tor/filters shall be provided.
Simultaneous economizer/compressor operation is also
possible. Dampers shall fully close on power loss.
•
MOTORIZED OUTDOOR AIR DAMPERS
- Outdoor and
return air dampers that are interlocked and positioned by
a 2-position, spring-return damper actuator. The maxi-
mum leakage rate for the outdoor air intake dampers
shall not exceed 2% when dampers are fully closed and
operating against a pressure differential of 0.5 IWG. A
unit-mounted potentiometer shall be provided to adjust
the outdoor and return air damper assembly to take in
the design CFM of outdoor air to meet the ventilation
requirements of the conditioned space during normal
operation. Whenever the indoor fan motor is energized,
the dampers open up to one of two pre-selected posi-
tions - regardless of the outdoor air enthalpy. Dampers
return to the fully closed position when the indoor fan
motor is de-energized. Dampers shall fully close on
power loss.
