Condensing Unit Specs.pdf

Guide Specifications - Condensing Units

- Condensers/Condensing Units

Part 1 - General

Related Documents

General Description

A. This section includes the design, controls and installation requirements for air-cooled condensers / condensing units.

Quality Assurance

A. Unit shall be certified in accordance with UL Standard 1995/CSA C22.2 No. 236, Safety Standard for Heating and Cooling Equipment.

B. Unit and refrigeration system shall comply with ASHRAE 15, Safety Standard for

Mechanical Refrigeration.

C. Energy Efficiency Ratio (EER) shall be equal to or greater than prescribed by

ASHRAE 90.1, Energy Efficient Design of New Buildings except Low-Rise

Residential Buildings.

D. Unit shall be safety certified by ETL and be ETL US and ETL Canada listed. Unit nameplate shall include the ETL label.

Submittals

A. Product Data: Literature shall be provided that indicates dimensions, operating and shipping weights, capacities, ratings, factory supplied accessories, electrical characteristics, and connection requirements. Installation, Operation and

Maintenance manual with startup requirements shall be provided.

B. Shop Drawings: Unit drawings shall be provided that indicate assembly, unit dimensions, clearances, and connection details. Wiring diagram shall be provided with details for both power and control systems and differentiate between factory installed and field installed wiring.

Delivery, Storage, and Handling

A. Unit shall be shipped with doors bolted shut to prevent damage during transport and thereafter while in storage awaiting installation.

B. Unit shall be plastic shrink-wrapped prior to shipment to prevent damage during transport and thereafter while in storage awaiting installation.

C. Follow Installation, Operation and Maintenance manual instructions for rigging, moving, and unloading the unit at its final location.

D. Unit shall be stored in a clean, dry place protected from construction traffic in accordance with the Installation, Operation and Maintenance manual.

Warranty

A. Manufacturer shall provide a limited “parts only” warranty for a period of 12 months from the date of equipment startup or 18 months from the date of original equipment shipment from the factory, whichever is less. Warranty shall cover material and workmanship that prove defective, within the specified warranty period, provided manufacturer’s written instructions for installation, operation and maintenance have been followed. Warranty excludes parts associated with routine maintenance and refrigerant.

Part 2 - Products

Manufacturer

A. Products shall be provided by the following manufacturers:

1. AAON, Carrier or approved substitute.

2. Substitute equipment may be considered for approval that includes at a minimum:

a. R-410A refrigerant

b. Hinged access doors with lockable handles

c. Variable capacity compressor with 10-100% capacity

d. 2,500 hour salt spray tested exterior corrosion protection

e. Designed, engineered, and manufactured in the United States of America

f. All other provisions of the specifications must be satisfactorily addressed

Condensing Units

A. General Description

1. Air-Source heat pump condensing unit shall include compressors, air-cooled condenser coils, condenser fans, suction and liquid connection valves, accumulator, receiver, reversing valve, filter driers with check valves, and thermal expansion valves.

2. Unit shall be factory assembled and tested including leak testing of the coil and run testing of the completed unit. Run test report shall be supplied with the unit in the control compartment.

3. Unit shall have decals and tags to indicate lifting and rigging, service areas and caution areas for safety and to assist service personnel.

4. Unit components shall be labeled, including pipe stub outs, refrigeration system components and electrical and controls components.

5. Installation, Operation and Maintenance manual shall be supplied within the unit.

6. Laminated color-coded wiring diagram shall match factory installed wiring and shall be affixed to the interior of the control compartment’s access door.

7. Unit nameplate shall be provided in two locations on the unit, affixed to the exterior of the unit and affixed to the interior of the control compartment’s access door.

B. Construction

1. Unit shall be completely factory assembled, piped, and wired and shipped in one section.

2. All cabinet walls, access doors, and roof shall be fabricated of G90 galvanized steel panels.

3. Unit shall be specifically designed for outdoor application.

4. Access to compressors and control components shall be through hinged access doors with quarter turn, lockable handles.

5. Access to condenser coils and fans is through removable access panels.

6. Exterior paint finish shall be capable of withstanding at least 2,500 hours, with no visible corrosive effects, when tested in a salt spray and fog atmosphere in accordance with ASTM B 117-95 test procedure.

7. Unit shall include lifting lugs.

C. Electrical

1. Unit shall be provided with standard power block for connecting power to the unit.

2. Control circuit transformer and wiring shall provide 24 VAC control voltage from the line voltage provided to the unit.

3. Unit shall have a 5kAIC SCCR.

4. Air-source heat pump shall include a defrost cycle to prevent frost accumulation on the outdoor coil during heat pump heating operation. Defrost cycle shall begin when outdoor coil temperature is below a fixed setpoint and have a fixed

10 minute run time, or end when the outdoor coil temperature is above a fixed setpoint. Defrost timer, with 30/60/90 minute selectable defrost cycle interval time, shall be factory installed in the controls compartment. During defrost cycle all compressors shall energize, reversing valve shall energize, and auxiliary heat shall energize.

5. Unit shall be provided with factory installed and factory wired, non-fused disconnect switch.

6. Unit shall be provided with phase and brown out protection which shuts down all motors in the unit if the electrical phases are more than 10% out of balance on voltage, the voltage is more than 10% under design voltage, or on phase reversal.

D. Refrigeration System

1. Unit shall be provided with four independently circuited R-410A variable capacity scroll compressors with thermal overload protection. Variable capacity scroll compressors shall be capable of modulation from 10-100% of its capacity.

2. Each compressor shall be furnished with a crankcase heater.

3. Compressors shall be mounted in an isolated service compartment which can be accessed without affecting unit operation. Lockable hinged access doors shall provide access to the compressors.

4. Compressors shall be isolated from the base pan with the compressor manufacturer’s recommended rubber vibration isolators and mounted on an elevated compressor deck, to reduce any transmission of noise from the compressors into the building area.

5. Each refrigeration circuit shall be equipped with automatic reset low pressure and manual reset high pressure refrigerant safety controls, Schrader type service fittings on both the high pressure and low pressure sides, and service valves for liquid and suction connections. Liquid line filter driers shall be factory provided and installed. Field installed refrigerant circuits shall include the low side cooling components, refrigerant, thermal expansion valve, liquid line, insulated hot gas reheat line, and insulated suction line.

6. Unit shall include a factory holding charge of R-410A refrigerant and oil.

Adjusting the charge of the system will be required during installation.

7. Lead refrigeration circuit shall be provided with modulating hot gas reheat valve, electronic controller, liquid line receiver, supply air temperature sensor and a dehumidification control signal terminal that enables the dehumidification mode of operation, and includes supply air temperature control to prevent supply air temperature swings and overcooling of the space. The matching indoor air handler must include a hot gas reheat coil and a check valve on the hot gas reheat line.

8. Unit shall be configured as an air-source heat pump. Each refrigeration circuit shall be equipped with a bypass loop including two liquid line filter driers with two check valves, reversing valve, suction line accumulator, liquid line receiver, and a bypass loop with check valve around a thermal expansion valve.

Reversing valve shall de-energize during the heat pump heating mode of operation. The matching indoor air handler must include a bypass loop with check valve around the thermal expansion valve.

9. Each capacity stage shall be equipped with a 5 minute off delay timer to prevent compressor short cycling. Each additional capacity stage shall be equipped with an adjustable, 20 second delay timer to prevent multiple capacity stages from starting simultaneously.

10. Each refrigeration circuit shall be equipped with suction and discharge compressor isolation valves.

11. Units shall be provided with a suction pressure transducer on each refrigeration circuit.

E. Fans

1. Condenser fan shall be vertical discharge, axial flow, direct drive fans.

2. Condensing unit shall be provided with an electrically commutated motor

(ECM) condenser fan, condenser head pressure controller, and discharge pressure transducers for modulating head pressure control to allow cooling operation down to 35°F. Fan motor shall be weather protected, single phase, direct drive, and totally enclosed air over (TEAO) with electronic protection.

F. Coils

1. Coils shall be designed for use with R-410A refrigerant and constructed of copper tubes with aluminum fins mechanically bonded to the tubes and aluminum end casings. Fin design shall be sine wave rippled.

2. Coils shall be designed for a minimum of 10°F of refrigerant sub-cooling.

3. Coils shall be hydrogen leak tested.

G. Controls

1. Unit shall be provided with a terminal block for field installation of controls.

Option shall include factory installed isolation relays.

Part 3 - Execution

Installation, Operation, and Maintenance

A. Installation, Operation and Maintenance manual shall be supplied with the unit.

B. Installing contractor shall install unit, including field installed components, in accordance with Installation, Operation and Maintenance manual instructions.

C. Start up and maintenance requirements shall be complied with to ensure safe and correct operation of the unit.