Carrier 50PQ - Manual (Page 16)

Guide specifications
(cont)
Each of these devices shall be wired thru the Signal-LOC^'^
circuit to prevent compressor restart until reset at the
thermostat The standard room thermostat shall contain a
"compressor malfunction light" designed to illuminate if any
of the beforementioned safety controls trip out the compres­
sor thru the lockout circuit Two-compressor units shall have
separate and independent refrigeration and control systems
designed to allow for standby operation of either compressor
if one is locked out Two-compressor units shall have 2-stage
compressor heat and cool with built-in electric strip heat lock
out to prevent resistance heat operation above 40 F ambient
Defrost control — An outdoor coil defrost control system
(Chronotemp®) shall be incorporated into the base unit to
prevent frost accumulation during heating cycle The defrost
cycle shall function on the basis of time and coil temperature
A 90-minute timer shall actuate a defrost mode only if coil
temperature is low enough to indicate a heavy frost condition.
Defrost shall have a positive termination time of a maximum
of 10 minutes or when the defrost thermostat is satisfied to
prevent prolonged operation on a defrost cycle Electric
resistance heaters shall be operational automatically during the
defrost cycle
Unit electrical connections — Unit with factory-installed
electric heat shall have single point power connection to a
terminal block. Cabinet shall contain suitable openings for
routing of all utility connections The base unit shall contain a
terminal strip in the control compartment to allow for
terminal-to-terminal connection of room thermostat and field-
installed accessories
Maximum dimensions — Width----------------- in., depth------------ in,
height-------- inches.
Accessories and options
The following factory-installed options, (FlOP) or field-
installed accessories (accessory) shall be provided.
Roof curb shall be of the same manufacture as unit and shall
include an insulated panel under compressor section to prevent
condensation forming on the bottom Dimensions shall be
provided to allow for easy duct location and connection to
roof curb prior to unit placement Roof curb shall be a
minimum of 12 in high to allow for proper defrost meltage
run-off Curb design shall comply with National Roofing
Contractors Association requirements (accessory)
Economizer control shall include R.A. and O.A dampers,
outdoor air filter and hood, and fully modulating electric
control system with O.A. thermostat and adjustable mixed air
stat. Economizer control shall be capable of introducing up to
100% outdoor air The control changeover from mechanical
cooling to economizer operation shall be fully automatic thru
an adjustable outdoor air changeover thermostat. PQ units
(accessory or FlOP) RQ units with accessory plenum
(accessory).
Alternate motor and drive assembly to provide added cfm and
static pressure capability (FlOP)
Downturn plenum for use on RQ units designed to easily field
attach to the base unit to direct airflow downward thru the
roof. Plenum to provide for a weatherproof opening for
ductwork assembly (accessory only on RQ units)
Electric resistance heaters shall be available in 4 selections
(low, 75 1, 1 1 , 1 5 1 heat-to-cool ratio) and shall have open
wire nichrome elements with all necessary safety and operating
controls. Heaters shall be U.L. listed and approved for use
when factory installed. Units with factory-installed heat shall
have single power entry by terminal blocks suitable for copper
or aluminum wires (200-v, 3-phase unit with 39 Kw factory-
installed heat, copper only)
Thermostat assembly shall provide staged heating and cooling,
manual or automatic changeover and fan control Standard
subbase shall include "compressor malfunction light" (LK-
OUT) designed to illuminate if compressor lockout is activated
(accessory)
Emergency heat control shall consist of emergency heal
control box containing emergency heat relays and outdoor
thermostat(s), and an emergency heal thermostat subbase
(with warning light) Control shall allow for manual bypass of
compressor and outdoor thermostats if compressor becomes
inoperative, or for service Subbase light shall illuminate if
compressor lock-out is activated. Outdoor thermostats shall
provide for staging of electric resistance heal according to
outdoor temperature Thermostats shall be wired into the
electric heater contactors and shall have an adjustable set point
to provide economical resistance heat staging (accessory).
Remote control panel to provide central unit control of
heating, cooling, indoor fan and outdoor air damper Panel
shall contain indicator lights for up lo 6 unit functions
(accessory)
Time Guard® circuit to prevent compressor short cycling as a
result of a rapid change in thermostat setting. Also, auto­
matically prevents compressor restart at least 5 minutes after
shutdown (accessory).
Head pressure control — A solid state outdoor fan speed
control (32LT) to maintain head pressure control down to
—20 F QAT on cooling cycle (accessory). (Inoperative during
heating cycle )
Number One
Air Conditioning
G
Division oi Carrier Corporation
Carrier Parkway • Syracuse NY 13221
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Tab 12 Form 50RQ-3P Supersedes 50RQ-2P Primed in U S A 10-77 PC 111 Catalog No 525—044
Book 1 4
Tab 5a 5a