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Packaged Rooftop Air-to-Air Heat Pump

By Mike Patterson,2014-05-05 09:10
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Packaged Rooftop Air-to-Air Heat Pump

HVAC Guide Specifications

    Packaged Rooftop Air-to-Air Heat Pump with Electric Heat Option Constant Volume Application

Size Range:

    3 to 10 Tons, Nominal Cooling

Carrier Model Number:

    50TFQ

Part 1 General

    1.01 SYSTEM DESCRIPTION

    Outdoor rooftop- or slab-mounted, electrically controlled air-to-air heat pump utilizing a hermetic

    compressor for heating and cooling duty. Unit shall discharge supply air vertically or horizontally as

    shown on contract drawings.

    1.02 QUALITY ASSURANCE

    A. Unit shall be rated in accordance with ARI Standards 210/240 and 270.

    B. Unit shall be designed to conform to ASHRAE 15, latest revision, and in accordance with UL

    1995.

    C. Unit shall be UL tested and certified in accordance with ANSI Z21.47 Standard and UL listed and

    certified under Canadian Standards as a total package for safety requirements.

    D. Roof curb shall be designed to conform to NRCA Standards.

    E. Insulation and adhesive shall meet NFPA 90A requirements for flame spread and smoke

    generation.

    F. Unit casing shall be capable of withstanding Federal Test Method Standard No. 141 (Method

    6061) 500-hour salt spray test.

    1.03 DELIVERY, STORAGE, AND HANDLING

    Unit(s) shall be stored and handled per manufacturer’s recommendations.

Part 2 Products

    2.01 EQUIPMENT (STANDARD)

    A. General:

    Factory-assembled, single-piece air-to-air heat pump. Contained within the unit enclosure shall

    be all factory wiring, piping, controls, refrigerant charge (R-22), and special features required prior

    to field start-up.

    B. Unit Cabinet:

    1. Unit cabinet shall be constructed of galvanized steel, bonderized and coated with a baked

    enamel finish on all externally exposed surfaces with primer coated internal panels. 12. Indoor fan cabinet interior shall be insulated with a minimum /-in. thick flexible fiberglass 2insulation coated on the air side.

    3. Cabinet panels shall be easily removable for servicing.

    4. Holes shall be provided in the base rails for rigging shackles to facilitate overhead rigging,

    and forklift slots shall be provided to facilitate maneuvering.

    5. Unit shall have a factory-installed, sloped condensate drain pan made of a non-corrosive 3material, providing a minimum /-in. connection with both vertical and horizontal drains and 4shall comply with ASHRAE 62.

    6. Unit shall have factory-installed filter access panel to provide filter access with tool-less

    removal.

    7. Unit shall have standard thru-the-bottom power connection capability.

    C. Fans:

    1. Indoor blower shall be of the direct- or belt-driven, double inlet, forward-curved centrifugal

    type. Belt drive shall include an adjustable-pitch motor pulley.

    2. Indoor blower shall be made from steel with a corrosion-resistant finish and shall be

    dynamically balanced.

    3. Bearings shall be of the sealed, permanently lubricated, ball-bearing type for longer life and

    lower maintenance.

    4. Outdoor fan shall be of the direct-driven propeller type and shall discharge air vertically.

    5. Outdoor fan shall have aluminum blades riveted to corrosion-resistant steel spiders and shall

    be dynamically balanced.

    D. Compressor(s):

    1. Fully hermetic type, internally protected.

    2. Factory rubber shock-mounted and internally spring mounted for vibration isolation.

    E. Coils:

    1. Outdoor and indoor coils shall have aluminum plate fins mechanically bonded to enhanced

    copper tubes with all joints brazed.

    2. Tube sheet openings shall be belled to prevent tube wear.

    3. Indoor coil shall be of the face split design.

    4. Coils:

    a. Copper-fin coils shall be constructed of copper fins mechanically bonded to copper tubes

    and copper tube sheets. Galvanized steel tube sheets shall not be acceptable. A polymer

    strip shall prevent coil assembly from contacting the sheet metal coil pan to minimize

    potential for galvanic corrosion between coil and pan. All copper construction shall

    provide protection in moderate coastal environments.

    b. E-Coated aluminum-fin coils shall have a flexible epoxy polymer coating uniformly

    applied to all coil surface areas without material bridging between fins. Coating process

    shall ensure complete coil encapsulation. Color shall be high gloss black with gloss 60

    deg of 65 to 90% per ASTM D523-89. Uniform dry film thickness from 0.8 to 1.2 mil on all

    surface areas including fin edges. Superior hardness characteristics of 2H per ASTM

    D3363-92A and cross-hatch adhesion of 4B-5B per ASTM D3359-93. Impact resistance

    shall be up to 160 in./lb (ASTM D2794-93). Humidity and water immersion resistance

    shall be up to minimum 1000 and 250 hours respectively (ASTM D2247-92 and ASTM

    D870-92). Corrosion durability shall be confirmed through testing to be no less than 1000

    hours salt spray per ASTM B117-90. Coil construction shall be aluminum fins

    mechanically bonded to copper tubes.

    c. E-Coated copper-fin coils shall have a flexible epoxy polymer coating uniformly applied to

    all coil surface areas without material bridging between fins. Coating process shall ensure

    complete coil encapsulation. Color shall be high gloss black with gloss 60 deg of 65 to

    90% per ASTM D523-89. Uniform dry film thickness from 0.8 to 1.2 mil on all surface

    areas including fin edges. Superior hardness characteristics of 2H per ASTM D3363-92A

    and cross-hatch adhesion of 4B-5B per ASTM D3359-93. Impact resistance shall be up

    to 160 in./lb (ASTM D2794-93). Humidity and water immersion resistance shall be up to

    minimum 1000 and 250 hours respectively (ASTM D2247-92 and ASTM D870-92).

    Corrosion durability shall be confirmed through testing to be no less than 1000 hours salt

    spray per ASTM B117-90. Coil construction shall be copper fins mechanically bonded to

    copper tubes with copper tube sheets. Galvanized steel tube sheets shall not be

    acceptable. A polymer strip shall prevent coil assembly from contacting sheet metal coil

    pan to maintain coating integrity and minimize corrosion potential between coil and pan.

    d. Optional precoated aluminum-fin coils shall have a durable epoxy-phenolic coating to

    provide protection in mildly corrosive coastal environments. Coating shall be applied to

    the aluminum fin stock prior to the fin stamping process to create an inert barrier between

    the aluminum fin and copper tube. Epoxy-phenolic barrier shall minimize galvanic action

    between dissimilar metals.

    F. Refrigerant Components: Refrigerant circuit components shall include:

    1. Acutrol? multiple independent circuit metering system.

    2. Service gage connections on suction, discharge, and liquid line to charge, evacuate, and

    contain refrigerant.

    3. Accumulator.

    4. Reversing valve.

    G. Filter Section:

    1. Standard filter section shall consist of factory-installed low-velocity, throwaway 2-in. thick

    fiberglass filters of commercially available sizes.

    2. Filter face velocity shall not exceed 300 fpm at nominal airflows.

    3. Filter section shall use only one size filter.

    4. Filters shall be accessible through an access panel with ‘‘no-tool’’ removal.

    H. Controls and Safeties:

    1. Unit Controls:

    a. Unit shall be complete with self-contained low-voltage control circuit.

    b. Unit shall incorporate an outdoor coil defrost system to prevent excessive frost

    accumulation during heating duty, and shall be controlled as follows:

    1) Defrost shall be initiated on the basis of time and coil temperature.

    2) A 30/50/90-minute timer shall activate defrost cycle only if coil temperature is low

    enough to indicate a heavy frost condition.

    3) Defrost cycle shall terminate when defrost thermostat is satisfied and shall have a

    positive termination time of 10 minutes.

    c. Unit shall contain high-pressure, loss-of-charge/low-pressure, and freeze protection

    switches. It shall mount on factory-installed Schrader fittings.

    2. Standard Safeties:

    Unit shall incorporate compressor overtemperature and overcurrent safety devices to shut off

    compressor.

    I. Operating Characteristics:

    1. Unit shall be capable of starting and running in cooling at 125 F ambient outdoor temperature,

    meeting maximum load criteria of ARI Standard 210/240 at ?10% voltage. 2. Compressor with standard controls shall be capable of cooling operation down to 25 F

    ambient outdoor temperature.

    3. Compressor shall be capable of operation in heating duty down to 10 F ambient outdoor-air

    temperature.

    4. Unit shall be capable of simultaneous heating duty and defrost cycle operation when using

    electric heaters indicated in Section L, Special Features.

    J. Electrical Requirements:

    All unit power wiring shall enter unit cabinet at a single factory-predrilled location.

    K. Motors:

    1. Compressor motors shall be cooled by refrigerant passing through motor windings and shall

    have line break thermal and current overload protection.

    2. Indoor blower motor shall have permanently lubricated bearings and inherent automatic-reset

    thermal overload protection.

    3. Totally enclosed outdoor-fan motor shall have permanently lubricated bearings, and inherent

    automatic-reset thermal overload protection.

    L. Special Features:

    Certain features are not applicable when the features designated by * are specified. For assistance in amending the specifications, your local Carrier Sales Office should be contacted. * 1. Carrier PremierLink? Controls:

    a. Shall be available as a factory-installed or as a field-installed accessory.

    b. Shall work with CCN and ComfortVIEW? software.

    c. Shall be compatible with ComfortLink? controllers.

    d. Shall be ASHRAE 62-99 compliant.

    e. Shall accept a CO sensor in the conditioned space Demand Control Ventilation 2(DCV) Ready.

    f. Shall have baud communication rate of 38.4K or faster.

    g. Shall be Internet Ready.

    h. Shall include an integrated economizer controller.

     2. Apollo Control:

    a. Shall serve as interface between thermostat, Carrier rooftop unit, and any external

    field-supplied sensors.

    b. Shall be powered by 24 vac/10 va, supplies thermostat with 10 vdc. This power is

    supplied by the Carrier rooftop unit, and is factory wired.

     3. Roof Curbs:

    a. Formed galvanized steel with wood nailer strip and capable of supporting entire unit

    weight.

    b. Allows for installing and securing ductwork to curb prior to mounting unit on the curb. * 4. Integrated Economizers:

    a. Integrated integral-modulating type capable of simultaneous economizer and

    compressor operation.

    b. Includes all hardware and controls to provide cooling with outdoor air.

    c. Equipped with low-leakage dampers not to exceed 3% leakage at 1 in. wg pressure

    differential (Durablade economizer).

    d. Capable of introducing up to 100% outdoor air in both minimum and fully open

    positions.

    e. Equipped with a gravity relief sliding plate damper (Durablade economizer). Damper

    shall close upon unit shutoff.

    f. EconoMi$er shall be equipped with a barometric relief damper with up to 100% of

    return air (004-007) or 90% of return air (008-012) relief. The Durablade economizer is

    equipped with 30% of return-air relief (004-012).

    g. Designed to close damper during loss-of-power situations with emergency power

    supply (Durablade economizer) or spring return built into motor (EconoMi$er).

    h. Dry bulb outdoor-air temperature sensor shall be provided as standard. Enthalpy

    control shall be provided as an option.

    i. Durablade economizer is a guillotine-style damper, and the EconoMi$er is a gear-

    driven, parallel blade design.

    NOTE: EconoMi$er shall also be available with field-installed two-stage power exhaust

    accessory for vertical or horizontal duct applications.

     5. 25% Manual Outdoor-Air Damper:

    Manual damper package shall consist of damper, birdscreen, and rainhood which can be

    preset to admit up to 25% outdoor air for year-round ventilation.

     6. 50% 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.

    * 7. 100% Two-Position Damper:

    a. Two-position damper package shall include single blade damper. Admits up to 100%

    outdoor air.

    b. Damper shall close upon indoor fan shutoff.

    c. Designed to close damper during loss of power situations.

    d. Equipped with barometric relief damper.

    * 8. 25% Two-Position Damper:

    a. Two-position damper package shall include single blade damper and motor. Admits up

    to 25% outdoor air.

    b. Damper shall close upon indoor fan shutoff.

    * 9. Solid-State Enthalpy Control:

    a. For use with Durablade economizer package only.

    b. Capable of sensing outdoor-air enthalpy content (temperature and humidity) and

    controlling economizer cut-in point to have minimum heat content air passing over the

    indoor coil for most efficient system operation.

    * 10. Differential Enthalpy Sensor:

    a. For use with economizer only.

    b. Capable of comparing enthalpy content (temperature and humidity) of outdoor and

    indoor air and controlling economizer cut-in point at the most economical level. * 11. Electric Resistance Heaters:

    a. Open wire nichrome elements with all necessary safety operating controls.

    b. UL listed and indicated on basic unit informative plate.

    c. Available in multiples to match heating requirements.

    d. Single point kits available for each heater when required.

    * 12. Head Pressure Control Packages:

    Consists of solid-state control and outdoor-coil temperature sensor to maintain condensing

    temperature between 90 F and 110 F at outdoor ambient temperatures down to 20 F by

    outdoor fan speed modulation or outdoor fan cycling.

    * 13. Thermostat and Subbase:

    Provides staged cooling and heating automatic (or manual) changeover, fan control, and

    indicator light.

     14. Thru-The-Bottom Service Connections:

    Kit shall provide connectors to permit electrical connections to be brought to the unit

    through the basepan.

    * 15. 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 controls.

     16. Energy$Recycler:

    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:

    a. 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.

    b. A supplementary supply air fan kit to provide increased air movement into the 62AQ

    unit.

    c. A field-installed 460v to 308/230v transformer to provide power when the

    Energy$Recycler is used with a 460V rooftop unit.

     17. EconoMi$er and Power Exhaust:

    Package shall provide control of internal building pressure. The two-stage system shall

    exhaust up to 100% of return air (vertical only).

     18. Two-Stage Power Exhaust Accessory for EconoMi$er:

    Power exhaust shall be used in conjunction with EconoMi$er to provide system exhaust of

    up to 100% of return air. The power exhaust is a field-installed accessory (vertical and

    horizontal applications).

    The individual fans are energized through the end switches located in the actuator, which

    will open as the outdoor-air damper opens. These end switches are factory set for 30 and

    70% of outdoor-air, and can be set to meet specific job requirements.

     19. Outdoor Air Enthalpy Sensor:

    The outdoor air enthalpy sensor shall be used with the EconoMi$er device to provide single

    enthalpy control. When used in conjunction with a return air enthalpy sensor, the

    EconoMi$er device will provide differential enthalpy control. The sensor allows the

    EconoMi$er controller to determine if outside air is suitable for free cooling.

     20. Return Air Enthalpy Sensor:

    The return air enthalpy sensor shall be used with the EconoMi$er device. When used in

    conjunction with an outdoor air enthalpy sensor, the EconoMi$er device will provide

    differential enthalpy control.

     21. Return Air Temperature Sensor:

    The return air temperature sensor shall be used with the EconoMi$er device. When used in

    conjunction with the standard outdoor air temperature sensor, the EconoMi$er device will

    provide differential temperature control.

     22. Indoor Air Quality (CO) Sensor: 2a. Shall have the ability to provide demand ventilation indoor air quality (IAQ) control

    through the economizer with an IAQ sensor.

    b. The IAQ sensor shall be available in duct mount, wall mount, and wall mount with LED

    display. The set point shall have adjustment capability.

     23. Power Exhaust Auxiliary Transformer:

    Field-installed 460v or 575 v to 230 v transformer to provide power to the 230 v power

    exhaust when attached to a 460 v or 575 v rooftop unit.

     24. Outdoor Coil Hail Guard Assembly:

    Hail guard shall protect against damage from hail and flying debris.

     25. Alternate Motors and/or Drives (004-006, 008, 012):

    Alternate motors and drives shall be factory-installed to provide additional performance

    range.

     26. High-Static Motor(s) and Drive(s) (50TFQ004-012):

    High-static motor(s) and drive(s) shall be factory-installed to provide an additional

    performance range.

     27. Outdoor Coil Grille:

    The grille protects the outdoor coil from damage by large objects without increasing unit

    clearances.

     28. Compressor Cycle Delay:

    Unit shall be prevented from restarting for a minimum of 5 min. after shutdown.

     29. Salt Spray Protection Package (008-012):

    Coil guard protects coil from corrosion in coastal areas and in areas with high sulfur

    emissions.

     30. Fan/Filter Status Switch:

    Provides status of evaporator fan (ON/OFF) or filter (CLEAN/DIRTY). Status shall be

    displayed over communication bus when used with direct digital controls or with an

    indicator light at the thermostat.

     31. Unit Mounted Disconnect Switch:

    Shall be factory-installed. Internally mounted, NEC and UL approved non-fused switch

    provides unit power shutoff. Shall be accessible from outside the unit.

     32. Convenience Outlet:

    Shall be factory-installed and internally mounted with easily accessible 115-v female

    receptacle. Shall include 15 amp GFI receptacle with independent fuse protection. Voltage

    required to operate convenience outlet shall be provided by a factory-installed step-down

    transformer. Shall be accessible from outside the unit.

     33. Emergency Heat Package:

    When mechanical heating is locked out, auxiliary heat shall be activated when necessary.

     34. Ultra-Violet Germicidal Lamps:

    Ultra-violet germicidal lamps are designed to eliminate odor causing mold and fungus that

    may develop in the wet area of the evaporator section of the unit. The high output, low

    temperature germicidal lamps are field installed in the evaporator section of the unit, aimed

    at the evaporator coil and condensate pan. The short wave-length ultra-violet light inhibits

    and kills mold, fungus and microbial growth. The lamps have an output rating at 45 F in 400 2fpm airflow of 120 microwatts/cm at 1 meter.

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