246695-YTG-C-0708
Johnson Controls Unitary Products
27
Refrigerant Circuit and Refrigerant Safety Components shall
include:
a.
Independent fixed-orifice or thermally operated expan-
sion devices.
b.
Solid core filter drier/strainer to eliminate any moisture or
foreign matter.
c.
Accessible service gage connections on both suction
and discharge lines to charge, evacuate, and measure
refrigerant pressure during any necessary servicing or
troubleshooting, without losing charge.
d.
The unit shall have two independent refrigerant circuits,
equally split in 50% capacity increments.
Unit Controls:
a.
Unit shall be complete with self-contained low-voltage
control circuit protected by a resetable circuit breaker on
the 24-volt transformer side.
b.
Unit shall incorporate a lockout circuit which provides
reset capability at the space thermostat or base unit,
should any of the following standard safety devices trip
and shut off compressor:
(1) loss-of-charge/Low-pressure switch,
(2) high-pressure switch,
(3) freeze-protection thermostat, evaporator coil.
c.
If any of the above safety devices trip, a LED (light-emit-
ting diode) indicator shall flash a diagnostic code that
indicates which safety switch has tripped.
d.
Unit shall incorporate “AUTO RESET” compressor over
temperature, over current protection.
e.
Unit shall operate with conventional thermostat designs
and have a low voltage terminal strip for easy hook-up.
f.
Unit control board shall have on-board diagnostics and
fault code display.
g.
Standard controls shall include anti-short cycle and low
voltage protection, and permit cooling operation down to
0
°
F.
h.
Control board shall monitor each refrigerant safety
switch independently.
i.
Control board shall retain last 5 fault codes in non vola-
tile memory, which will not be lost in the event of a power
loss.
GAS HEATING SECTION (IF EQUIPPED)
Heat exchanger and exhaust system shall be constructed of
aluminized steel or optional stainless steel. Shall be designed
with induced draft combustion with post purge logic, energy
saving direct spark ignition, and redundant main gas valve.
The heat exchanger shall be of the tubular type, constructed
of T1-40 aluminized steel (or optional 304 stainless steel) for
corrosion resistance and allowing minimum mixed air enter-
ing temperature of 40
°
F. Burners shall be of the in-shot type,
constructed of aluminum-coated steel. All gas piping shall
enter the unit cabinet at a single location, through either the
side or bottom, without any field modifications. An integrated
control board shall provide timed control of evaporator fan
functioning and burner ignition. Heating section shall be pro-
vided with the following minimum protection:
a.
Primary and auxiliary high-temperature limit switches.
b.
Induced draft pressure sensor.
c.
Flame roll out switch (manual reset).
d.
Flame proving controls. Unit shall have two independent
stages of capacity (60% 1
st
stage, 100% 2
nd
stage).
ELECTRIC HEATING SECTION (IF EQUIPPED)
An electric heating section, with nickel chromium elements,
shall be provided in a range of 9 thru 54 KW, offering two
stages of capacity all sizes. The heating section shall have a
primary limit control(s) (automatic reset) to prevent the heat-
ing element system from operating at an excessive tempera-
ture. The Heating Section assembly shall slide out of the unit
for easy maintenance and service. Units with Electric Heating
Sections 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 out-
door temperature, exceeding maximum load criteria of ARI
Standard 340/360. The compressor, with standard controls,
shall be capable of operation down to 0
°
F outdoor tempera-
ture. 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, Elect.
Heat Elem. – 5 Years, Parts – 1 Year
FACTORY INSTALLED OPTIONAL OUTDOOR AIR (Shall
be made available by either/or):
1.
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 outdoor air to meet the
minimum ventilation requirement of the conditioned
