Building HVAC (Equipment w/Factory Installed Controls)
48HJ Series Rooftops with PremierLINK
High Efficiency 48 Series Rooftop w/ Elec. Cool & Gas Heat - Sequence of Operation
Packaged Rooftop Electric Cooling Unit with Gas Heat — Constant Volume Application
Size Range: 3 to 121/2 Tons, Nominal (Cooling)
60,000 to 250,000 Btuh, Nominal (Input Heating)
Carrier Model Numbers: 48HJD/L/G, 48HJE/M/H, 48HJF/N/K
Note: The following is a sample of a typical Sequence of Operation that may be adapted for a particular project. This is provided as a suggestion on how to write a Sequence of Operation for a specific project. The Rooftop Controller includes the ability for the operator to select some different sequences. Consult your Carrier representative if the sample sequence requires alterations.
4.2.8 Rooftop w/ Elec. Cool & Gas Heat , Constant Volume, Communicating, Product Integrated
Control (PIC), Sequence of Operation
188.8.131.52 Sequence of Operation Description
Outdoor rooftop mounted, Microprocessor controlled, heating and cooling unit utilizing a hermetic compressor(s) for cooling duty and gas combustion for heating duty. Unit shall discharge supply air vertically or horizontally as shown on contract drawings. Rooftop communicates with and sends alarms to, the building automation network and alarm printer.
184.108.40.206 Controls and Safeties
A. Unit Controls:
Unit shall be complete with self-contained low voltage control circuit protected by a fuse on the 24 V
transformer side (008-014 units have a re-settable circuit breaker).
1. Unit shall incorporate a solid-state compressor protector which provides anti-cycle reset capability at
the space thermostat, should any of the following standard safety devices trip and shut off
A. Compressor over temperature, over-current
B. Loss-of-charge/low-pressure switch
C. Freeze-protection thermostat, evaporator coil
D. High-pressure switch
E. Automatic reset motor thermal overload protector.
The lockout protection shall be easily disconnected at the control board, if necessary.
2. Heating section shall be provided with the following minimum protections:
A. High-temperature limit switches
B. Induced draft motor speed sensor
C. Flame rollout switch
D. Flame proving controls.
NOTE: Certain features are not applicable when the features designated * are specified. For assistance in amending the specifications, contact your local Carrier Sales Office.
C. *Carrier PremierLink? Controls:
1. Shall be available as a factory-installed or as a field-installed accessory. 2. Shall work with CCN and ComfortVIEW? software.
3. Shall be compatible with ComfortLink? controllers.
4. Shall be ASHRAE 62-99 compliant.
5. Shall accept a CO2 sensor in the conditioned space - Demand Control Ventilation (DCV) ready. 6. Shall have baud communication rate of 38.4K or faster.
7. Shall be Internet ready.
8. Shall include an integrated economizer controller.
9. If an economizer is specified, the ―EconoMi$er2 with 4–20 mA actuator and no microprocessor
control‖ is required.
D. *Integrated Economizers:
1. Integrated integral modulating type capable of simultaneous economizer and compressor operation.
During economizer operation, only compressor no. 1 on sizes 008-014 will operate. 2. Available as a factory-installed option in vertical supply/return configuration only. (Available as a
field-installed accessory for horizontal and/or vertical supply return configurations.) 3. Includes all hardware and controls to provide cooling with outdoor air.
4. Equipped with low-leakage dampers, not to exceed 2% leakage at 1 in. wg. pressure differential. 5. Capable of introducing up to 100% outdoor air.
6. EconoMi$er2 shall be equipped with a barometric relief damper.
7. Designed to close damper(s) during loss of power situations with emergency power supply
(Durablade economizer) or spring return built into motor (EconoMi$er2).
8. Dry bulb outdoor air temperature sensor shall be provided as standard. Outdoor air sensor opens at
67?F, closes at 52?F and is non-adjustable. Enthalpy, differential temperature (adjustable), and
differential enthalpy control shall be provided as field installed accessories. 9. Durablade economizer is a guillotine-style damper, and the EconoMi$er2 is gear-driven parallel
10. EconoMi$er2 microprocessor control shall provide control of internalbuilding pressure through its
accessory power exhaust function. Factory set at 100%, with a range of 0% to 100%. 11. EconoMi$er2 shall be capable of control from a 4–20 mA signal through optional 4–20 mA design
without microprocessor control (required for PremierLink? or 3rd party control interface).
12. EconoMi$er2 Microprocessor Minimum Damper Position Setting — potentiometer maintains the
minimum airflow into the building during occupied period (damper position during heating). 13. EconoMi$er2 Microprocessor Maximum Damper Position Setting — potentiometer allows installer
to limit the amount of outdoor airflow into the building, when CO2 overrides the mixed air sensor.
Setting the maximum position of the damper prevents the introduction of large amounts of hot or
cold air into the space.
14. EconoMi$er2 Microprocessor IAQ control — modulates the outdoor-air damper to provide
ventilation based on the optional 2-10 VDC CO2 sensor input.
15. EconoMi$er2 Microprocessor Purge or Shutdown modes: require optional Honeywell S963B1128
potentiometer (135 ohm).
16. Compressor lockout sensor (opens at 35?F, closes at 50?F).
E. Manual Outdoor Air Damper:
Manual damper package shall consist of damper, birdscreen and rainhood which can be preset
to admit up to 50% outdoor air for year round ventilation.
F. *100% Two-Position Damper:
1. Two-position damper package shall include single blade damper and motor. Admits up to 100%
2. Damper shall close upon indoor (evaporator) fan shutoff.
3. Designed to close damper during loss of power situations.
4. Equipped with 15% barometric relief damper.
G. *25% Two-Position Damper:
1. Two-position damper package shall include single blade damper and motor. Admits up to 25%
2. Damper shall close upon indoor (evaporator) fan shutoff.
H. *Head Pressure Control Package:
Consists of solid-state control and condenser coil temperature sensor to maintain condensing
temperature between 90?F and 110?F at outdoor ambient temperatures down to -20?F by
condenser-fan speed modulation or condenser fan cycling and wind baffles.
I. *Electronic Programmable Thermostat:
Capable of using deluxe full-featured electronic thermostat. Shall use built-in compressor cycle
delay control for both heating and cooling duty. Capable of working with Carrier direct digital
J. Fan/Filter Status Switch:
Provides status of indoor (evaporator) fan (ON/OFF) or filter (CLEAN/DIRTY). Status shall be
displayed over communications bus when used with direct digital controls or with an indicator
light at the thermostat.
The package shall be an outdoor rooftop or surface mounted, electronically controlled, air-to-air heat
pump unit utilizing a hermetic compressor for cooling and heating duty. The Energy$Recycler shall
recover energy from building exhaust air and pre-condition ventilation air to allow higher ventilation
requirements and minimizing energy cost.
This option shall be available with the following:
1. A mounting kit for the Energy$Recycler for cantilever mounting off of the rooftop unit with
out the use of a slab or a roof curb.
2. A supplementary supply air fan kit to provide increased air movement into the 62AQ unit.
3. A field installed 460 V to 208/230 V transformer to provide power when the 208-230/1/60
62AQ060 or 100 size Energy$Recycler is used with a 460 V rooftop unit.
L. EconoMi$er2 and Power Exhaust
Package shall provide control of internal building pressure. The power exhaust system shall
exhaust up to 100% of return air (vertical only).
M. Power Exhaust Accessory for EconoMi$er2
Power exhaust shall be used in conjunction with EconoMi$er2 to provide system exhaust of up to
100% of return air (vertical only). The power exhaust is a field-installed accessory (separate vertical
and horizontal design).
Note: Horizontal power exhaust is intended to mount in return ductwork. As the outdoor-air damper
opens and closes, both propeller fans are energized and de-energized through the end switch
(potentiometer) located on the EconoMi$er2 controller. The end switch is factory set at 100% of
outdoor air, and is adjustable 0-100% to meet specific job requirements. Available in 208/230-1-60 V
or 460-3-60 V. An LED light on the controller indicates when the power exhaust is operating.
N. Outdoor Air Enthalpy Sensor:
The outdoor air enthalpy sensor shall be used with the EconoMi$er2 device to provide single enthalpy
control. When used in conjunction with a return air enthalpy sensor, the EconoMi$er2 device will
provide differential enthalpy control. The sensor allows the EconoMi$er2 controller to determine if
outside air is suitable for free cooling.
O. Return Air Enthalpy Sensor:
The return air enthalpy sensor shall be used with the EconoMi$er2 device. When used in conjunction
with an outdoor air enthalpy sensor, the EconoMi$er2 device will provide differential enthalpy control.
P. Return Air Temperature Sensor:
The return air temperature sensor shall be used with the EconoMi$er2 device. When used in conjunction with the standard outdoor air temperature sensor, the EconoMi$er2 device will provide differential temperature control.
Q. Outdoor Air/Return Air Temperature Sensor (Adjustable):
Optional sensor uses (4) ranges on EconoMi$er2 microprocessor to control outdoor-air damper and compressor operation.
R. Indoor Air Quality (CO2) Sensor:
1. Shall have the ability to provide demand ventilation indoor air quality (IAQ) control through the
EconoMi$er2 with an IAQ sensor.
2. The IAQ sensor shall be available in duct mount, wall mount, and wall mount with LED display. The
setpoint shall have adjustment capability.
3. Require EconoMi$er2, PremierLink?, or Apollo control options.
S. MoistureMi$er? Dehumidification Package:
The dehumidication package is a factory installed option that provides increased dehumidification by further subcooling the hot liquid refrigerant leaving the condenser coil. The package consists of a subcooling coil located on the leaving airside of the evaporator coil. The location of this coil in the indoor air stream greatly enhances the latent capacity of the units.
The package shall be equipped with crankcase heater(s), low pressure switch(es) and thermostatic expansion valve(s) (TXV). Low pressure switch(es) prevents evaporator coil freeze-up and TXVs assure a positive superheat condition.
If the operation of the subcooling coil is controlled by a field-installed, wall-mounted humidistat, the dehumidification circuit will then operate only when needed. Optional field connections for the humidistat are made in the low voltage compartment of the unit control box.
Field-installed, wall-mounted humidistat is used to control activation of the dehumidification package. The humidistat can be set for humidity levels between 20% and 80% relative humidity.