257098-BTG-A-0506
38
Unitary Products Group
brazed. Special Phenolic coating shall be available
as a factory option.
b.
Evaporator and Condenser coils shall be of the
direct expansion, draw-thru, design.
Refrigerant Circuit and Refrigerant Safety Components shall
include:
a.
Independent fixed-orifice expansion devices.
b.
Filter drier/strainer to eliminate any moisture or for-
eign matter.
c.
Accessible service gage connections on both suc-
tion and liquid lines to charge, evacuate, and mea-
sure refrigerant pressure during any necessary
servicing or troubleshooting without losing charge.
d.
The refrigeration system shall provide at least 15°F
of sub-cooling at design conditions.
UNIT CONTROLS
a.
Unit shall be complete with self-contained low-volt-
age control circuit protected by a resetable circuit
breaker on the 24-volt transformer side.
b.
Unit shall incorporate a lockout circuit which pro-
vides reset capability at the space thermostat or
base unit, should any of the following standard
safety devices trip and shut off compressor.
c.
Loss-of-charge/Low-pressure switch.
d.
High-pressure switch.
e.
Freeze-protection thermostat, evaporator coil.
f.
If any of the above safety devices trip, a LED (light-
emitting diode) indicator shall flash a diagnostic
code that indicates which safety switch has tripped.
g.
Unit shall incorporate “AUTO RESET” compressor
over temperature, over current protection.
h.
Unit shall operate with conventional thermostat
designs and have a low voltage terminal strip for
easy hook-up.
i.
Unit control board shall have on-board diagnostics
and fault code display.
j.
Standard controls shall include anti-short cycle and
low voltage protection, and permit cooling operation
down to 0°F.
k.
Control board shall monitor each refrigerant safety
switch independently.
l.
Control board shall retain last 5 fault codes in non
volatile memory, which will not be lost in the event of
a power loss.
ELECTRIC HEATING SECTION
An electric heating section, with nickel chromium elements,
shall be provided in a range of 5 thru 30 KW, offering two
stages of capacity - 16 KW and above on 208/230 volt heat-
ers and 20 KW and above on 460 and 575 volt heaters. The
heating section shall have a primary limit control(s) and auto-
matic reset to prevent the heating element system from oper-
ating at an excessive temperature. The heating section
assembly shall slide out of the unit for easy maintenance and
service. Units with Electric Heating shall be wired for a single
point power supply with branch circuit fusing (where
required).
UNIT OPERATING CHARACTERISTICS
a.
Unit shall be capable of starting and running at
125°F outdoor temperature, exceeding maximum
load criteria of ARI Standard 210/240.
b.
The compressor, with standard controls, shall be
capable of operation down to 0°F outdoor tempera-
ture.
c.
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
•
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-