unitedcoolair.com · Web viewAll co-axial heat exchanger water channels shall be fabricated with spiral tubing fabricated out of non-ferrous tubing. Heat exchangers shall incorporate

1 Options and unit configurations are indicated in Red and/or brackets [ ] which indicate required choices to be made.

This Engineering Specification is intended for the use of an Engineer when creating an HVAC guide specification that is applicable to a specific project. User should delete any portions of text or descriptions that are not applicable to the specific project. It shall be the responsibility of the Engineer to meet any components or configurations required for applicable building codes, industry standards and system commissioning. Engineer shall coordinate with other product specifications along with any applicable drawings.

Individuals should confirm that the latest version of this Engineering Specification is being utilized by visiting www.unitedcoolair.com.

Engineering Specification for Indoor Self Contained Water-Cooled VariCool EZ-FitManufacturer reserves the right to make changes without notice. 40.21-ES (1014) (WP)

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VariCool EZ-Fit

Self-Contained Indoor Floor Mounted

Air Conditioning System

ENGINEERING SPECIFICATION DATA

WATER-COOLED UNITS

Part 1 – General

1.01 Related Documents

A. Drawings and general provisions of the contract, including General and Supplementary Conditions and other Division 1 specification sections, apply to this section.

1.1 General Description

A. Furnish and install an indoor self-contained vertical air conditioner system designed to control space temperature and humidity levels. It shall have the performance, electrical characteristics, and air path configurations as defined in the product schedule for the space to be conditioned.

B. The unit(s) shall be a VariCool EZ-Fit modular water-cooled model manufactured by United CoolAir, York, Pennsylvania.

C. The unit(s) shall be installed as a single package floor mounted system.

D. All systems shall be shipped with a full factory refrigerant charge and be ready to wire and pipe once the unit has been placed on site.

E. A wiring diagram shall be affixed to each unit. A printed Installation, Operation and Maintenance Manual shall be provided with each unit. All units shall be suitably labeled for safety purposes and for access.

1.2 Quality Assurance

A. Unit and refrigeration system(s) shall comply with ASHRAE 15, Safety Standard for Mechanical Refrigeration.


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B. Unit shall be certified in accordance with UL Standard 1995/CSA C22.2No. 236-11, safety Standard for Heating and Cooling Equipment.

C. Unit shall be factory evacuated, charged with refrigerant R-410A, leak tested, and functionally tested as a complete system prior to shipment.

1.3 Submittals

A. Literature shall be provided that indicates unit dimensions, applicable clearances, unit operating weights, capacities, blower performance, filter information, factory supplied options, electrical characteristics, and connection requirements.

B. Installation, Operation, and Maintenance manual along with start-up procedure shall be provided.

1.4 Delivery, Storage, and Handling

A. Sections shall be shipped with all access panels in place and suitably affixed to prevent damage during transportation and thereafter while in storage either offsite or on the jobsite.

B. Unit and/or unit modules shall be stored in a clean, dry place protected from construction traffic and the natural elements.

C. Installing contractor shall follow industry accepted practices and instructions in the Installation, Operation and Maintenance manual for moving unit and/or modules and for the assembly of modules where required.

D. Units shall fit through a standard 3-0 doorway without building modifications.

E. Unit or section of the unit shall not be disassembled in the field, except as designed for, in order to facility placement into the building or mechanical space. Any disassembly of the unit or unit sections not incorporated into the basic design would act to void the unit warranty and reduce the factory quality assurance process.

1.5 Warranty

A. Manufacturer shall provide a “parts only” limited warranty for a period of 12 months from the date of equipment start-up or 18 months from date of shipment from the factory, whichever is less.


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B. Manufacturer shall provide a “compressor parts only” limited warranty for a period of 60 months from the date of equipment start-up or 66 months from date of shipment from the factory, whichever is less.

C. Manufacturer’s limited warranty shall be for parts only. Labor is not included.

Part 2 – Products

2.01 Cabinet

A. Cabinet shall be unpainted non-weatherized and constructed of scratch resistant heavy duty galvanized G90 steel.

A. Cabinet shall be painted non-weatherized construction of scratch resistant heavy duty galvanized G90 steel. All structural members and access panels shall be electrostatically sprayed, powder-coated with a polyester wrinkle finish textured coating designed to function as both a decorative and a protective finish. Film thickness shall be in the range of 2.5 – 4.0 mils and be cured at 375 deg. F. for a minimum of 10 minutes.

Finish shall have a Salt Spray Resistance of 1500+ hours – 1/8” vertical scribe, in accordance with ASTM B117.

Color shall be Rohm & Haas, Corvel 244-0253 Stormy Gray or approved equal.

B. Cabinet shall be modular in construction, shipped in multiple sections (3-8), on separate skids, depending on unit size in order to facilitate rigging and placement. Factory shall supply suitable devices for assisting in the rigging of the modules for moving and unit assembly.

C. Cabinet access panels shall fit into recessed pockets within the cabinet structure and held in place with screws. Recessed areas will be lined with flexible gasket to minimize air leakage.

D. Unit shall be provided with removable hinged doors to provide access to variable frequency drive and controls. Hinges shall be fiberglass-reinforced thermoplastic. Access doors shall have tool operated compression latches. Access doors shall be lined with flexible gasket to minimize air leakage.

E. Panels and doors shall allow access to key internal components to facilitate installation, maintenance and servicing of the unit.


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F. Inlet and outlet water connections will be located on the [Left] [Right] side of the cabinet independent of electrical connection.

G. Electrical connection will be located on the [Left] [Right] side of the cabinet independent of water connections.

H. All duct flanges shall be factory-installed on each unit prior to shipment.

I. Water piping shall be wrapped in a material that hinders any formation of condensate on the piping.

J. Insulation shall be 1” mat-faced thermal / acoustic and have an approximate density of 1.9 lbs. / ft3 and a thermal conductivity of 0.13 BTU/ (hr.) (ft2) (°F/in) @ 75° F mean temperature. The insulation shall be dual density fiberglass comprised of a 1.2 lbs. / ft3, flexible core insulation with a 4.0 lbs. / ft3 density, 1/8” fiberglass mat-face. Composite insulation shall be made from fire-resistant, non-corrosive inorganic glass fibers bonded by a thermosetting resin. Insulation shall be installed on the interior top, side and bottom pans, doors and panels. Insulation must meet NFPA 90A and 90B/ASTM-C1071, Type 1 requirements as well as Canadian CGSB 51-GP-11M and CAN 4-s102.

J. Acoustic Foam Insulation - Cabinet and removable doors and panels shall be lined with metalized Mylar-faced acoustical foam insulation. Insulation shall meet the requirements of ASTM D3574-86 for Tear Strength, Tensile Strength, Compression Set and Elongation. Insulation shall have chemical resistance to fluids such as moisture, petroleum, solvents, and alkalis. Flammability shall meet MVSS 302, UL-94 HF1 and FAR 25.853(b). Thermal conductivity shall be 0.25 BTU/ (hr.) (Ft2) (Deg. F/in.)

J. Elastomeric Foam Insulation – Cabinet and removable doors and panels shall be lined with a flexible, closed-cell elastomeric insulation in sheet form. Insulation materials shall have a closed-cell structure to prevent moisture from wicking. Materials shall have a maximum water vapor transmission of 0.08 perm-inches when tested in accordance with ASTM E 96, Procedure A, latest revision. Insulation material shall be manufactured without the use of CFC’s, HFC’s or HCFC’s. Insulation shall be formaldehyde free, low VOC’s, fiber free, dust free and shall resist mold and mildew. Materials shall have a flame spread index of less than 25 and a smoke-developed index of less than 50 when tested in accordance with ASTM E 84, latest revision. Materials shall have a maximum


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thermal conductivity of 0.27 Btu-in./h-ft2-°F at a 75 °F mean temperature when tested in accordance with ASTM C 177 or ASTM C 158, latest revisions.

J. Double Wall with Perforated Liner - Cabinet and removable doors and panels shall be double-wall construction with 1” mat-faced thermal / acoustic insulation and have an approximate density of 1.9 lbs. / ft3 and a thermal conductivity of 0.13 BTU/ (hr.) (ft2) (°F/in) @ 75° F mean temperature. The insulation shall be dual density fiberglass comprised of a 1.2 lbs. / ft3, flexible core insulation with a 4.0 lbs. / ft3 density, 1/8” fiberglass mat-face. Composite insulation shall be made from fire-resistant, non-corrosive inorganic glass fibers bonded by a thermosetting resin. Cabinet interior panels and doors shall be perforated galvanized metal with 1/8” holes spaced on 3/16” staggered centers.

J. Double Wall with Solid Liner - Cabinet and removable doors and panels shall be double-wall construction with 1” mat-faced thermal / acoustic insulation and have an approximate density of 1.9 lbs. / ft3 and a thermal conductivity of 0.13 BTU/ (hr.) (ft2) (°F/in) @ 75° F mean temperature. The insulation shall be dual density fiberglass comprised of a 1.2 lbs. / ft3, flexible core insulation with a 4.0 lbs. / ft3 density, 1/8” fiberglass mat-face. Composite insulation shall be made from fire-resistant, non-corrosive inorganic glass fibers bonded by a thermosetting resin. Cabinet interior panels and doors shall be solid galvanized metal.

2.02 Refrigerant Circuit

A. Each refrigerant circuit shall be provided with high and low-side Schrader access valves, sight glass with integral moisture indicator, filter-drier, maximum operating pressure (MOP) expansion valve with external equalizer line, manual reset high and auto-reset low pressure safety switches.

B. Each refrigerant circuit will be factory leak tested, evacuated, and charged with R-410A refrigerant prior to shipment. No field piping, brazing, evacuation or refrigerant charging shall be required.

C. Each separate section containing refrigerant circuit components shall be provided with resealable refrigerant fittings in order to preserve the factory refrigerant charge and to facilitate assembly of sections without loss of the refrigerant circuit integrity.


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D. Each refrigerant circuit shall be provided with a factory-installed pressure actuated hot gas bypass valve capability that diverts a portion of discharge gas directly into the inlet of the evaporator coil.

E. Each refrigerant circuit shall include manual shutoff valves on hot gas bypass lines to be used for isolation of the hot gas bypass capability during unit start-up, testing, or maintenance.

2.03 Compressors

A. Compressors shall be high-efficiency, heavy duty, single-speed, suction-cooled hermetic scroll type, operating at 3450 RPM on 60Hz. The compressor shall contain internal overload protection.

B. No compressor shall be nominally rated larger than 15 tons.

C. Compressor shall utilize internal spring vibration isolators and external rubber in shear (RIS) mounting to minimize sound and vibration transmission.

D. Units with multiple compressors shall have separate independent refrigerant circuits.

E. Staging of the compressors shall be controlled by the microprocessor based on the supply air temperature.

F. Digital Scroll Compressor - Lead compressor shall be a hermetically sealed digital scroll type.

G. Compressor Acoustic Cover - Each compressor shall be provided with a removable compressor cover using 1.2-2# density acoustical fiberglass, surrounded by a tough, durable, weather-proof, flame resistant covering.

H. Compressor Crankcase Heater - Each compressor shall be provided with a wraparound electrical cable resistance heater used to prevent migration and condensation of liquid refrigerant to the compressor crankcase while system is off.

2.04 Evaporator Coil Section

A. The direct expansion evaporator coil shall be configured for draw-thru airflow design for uniform air distribution across the coil face. It shall be made with heavy wall rifled seamless copper tubes mechanically expanded into tempered aluminum fins with corrugated fin design and drawn self-spacing collars. Coil


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end sheets shall be hot-dipped galvanized. All coils shall be factory leak checked under pressure.

B. Coils shall be interlaced, 4 rows deep with no more than 12 FPI, for uniform performance and optimum part load and humidity operation.

C. The evaporator coil shall utilize a distributor with suitable porting for injection of hot gas bypass. Maximum Operating Pressure (MOP) externally equalized balance port thermostatic expansion valves, externally equalized, shall feed each circuit in the evaporator coil.

D. Evaporator coil section shall be equipped with a 304 stainless steel drain pan. Drain pan shall extend to the entire length and width of the evaporator coil. Units shall have a single 1-1/4” NPT condensate drain connection for each module.

E. Evaporator section air path shall be as shown on project drawings.

2.05 Water-Cooled Condensing Section

A. The water / glycol condenser coils shall be a co-axial counter-flow refrigerant type. The condensers shall be selected to maintain low refrigerant operating pressure, while using a minimum quantity of water / glycol. Maximum working pressures shall not exceed 450 psig water side, 650 psig refrigerant side.

B. All co-axial heat exchanger water channels shall be fabricated with spiral tubing fabricated out of non-ferrous tubing. Heat exchangers shall incorporate longitudinal fins, spirally-wound and soldered to the inner tube with an outer tube serving as a shell.

C. Each circuit shall provide liquid sub-cooling of the refrigerant.

D. All systems, single or dual module, shall have a single grooved end water supply connection and a single grooved end return connection. Dual module systems internal water interconnecting piping shall be grooved end connections.

E. Each system shall be controlled by a single water-regulating valve with a modulating direct-coupled non-spring return actuator. Valve shall regulate fluid flow to control refrigerant head pressure. Valve shall be connected to cooling fluid piping using threaded connections. Valve shall be 2-way pressure-actuated configuration. Valve shall be rated for a 350 psig fluid pressure circuit.


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F. Shell and Tube Condenser - The horizontal shell and tube condensers shall have removable heads with mechanically cleanable tubes. Heat exchangers shall be fabricated to meet ASME certified standards. Condensers shall be designed for 150 psig cooling fluid side pressure and 600 psig for the refrigerant side pressure. Condensers shall be constructed of heavy duty steel enclosures with steel tube sheets, steel heads and heavy wall enhanced copper tube geometry. Removable, epoxy coated, heads shall have high quality replaceable gaskets. Shell and tube condensers shall have epoxy coated tube sheets to prevent pitting caused by galvanic action. Tube sheets, water and refrigerant fittings are to be machine welded. Tubes shall be rolled into tube sheets. Each condenser shall be equipped with a SAE flare connection high pressure relief valve. Condensers shall be piped with threaded couplings for easy removal of fluid piping for mechanical cleaning.

2.06A Blower / Motor Assembly (DWDI – 12 through 25 Ton Single or 24 through 50 Ton Dual)

A. The blower assembly shall be a belt driven double width double inlet airfoil housed fan. The fan shall incorporate a corrosion resistant steel impeller with 10 (x 2) true airfoil shaped blades which are continuously welded. All wheels are to be coated with an anticorrosive primer and a final layer of epoxy paint. A galvanized spot welded housing and inlet cone shall be utilized. The inlet cones are to be bolted onto the housing side plates.

B. The impeller and shaft shall be statically and dynamically balanced to an accuracy of G = 2.5 in accordance to DIN ISO 1940-1 and ANSI S2.19-1989. The fan shall comply with the requirements and in accordance with DIN, ISO, BS and AMCA.

C. The impeller shall be secured to the shaft via an aluminum hub. Hub bore shall be precision machined and incorporate a keyway and locking screw. Shaft shall be designed with the first critical speed well in excess of the maximum fan speed. Shafts shall be fabricated from hardened steel, precision ground and polished and include keyways for the wheel hub and sheaves. The shaft is to have a protective paint added for corrosion protection.

D. Blower bearings are to be self-aligning, single row, deep groove ball type, in pillow block cast iron housings. Bearings are to have an L50 life time of 200,000 hours (as per AFBMA standards). The pillow block bearings shall be mounted on a flat iron bar, welded to the “T” frame. All bearings shall be


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complete with re-lubrication fitting factory installed. The operating temperature range shall be from -4° F to +176° F.

E. The blower V-belt pulley shall be of cast iron construction and keyed to the blower shaft. Motor sheave shall be cast iron, keyed and variable pitch design to allow for field adjustment of specific airflow and static requirements.

F. The motor shall be an EPACT premium efficiency open drip proof, T-frame having class B insulation, NEMA B design and having a 1.15 service factor. Motor shall have permanently lubricated ball bearings. The motor shall be mounted to an adjustable motor frame.

G. Belt(s) shall be sized for 200% of motor horsepower.

[Direct Drive Parallel Fans (DDP) 12 through 25 ton single or 24 through 50 ton dual]

A. Units with the Direct Drive Parallel Fan (DDP) system shall consist of dual fans in each module. A single VFD shall be used to drive the dual fans and shall not have any speeds blocked out.

B. The blower assembly shall be direct driven non-overloading type backward inclined unhoused fans. The fan shall incorporate a corrosion resistant aluminum impeller with extruded airfoil shaped blades which are continuously welded. The front panel shall have a removable inlet cone.

C. Blower assemblies shall be mounted on a heavy-gauge galvanized steel frame and front panel. The design shall insure structural integrity of the base to minimize any vibration. The motor base shall insure proper alignment to the fan wheel, motor and inlet cone.

D. The fans shall be dynamically balanced as a complete unit in accordance with ISO 1940, to achieve Balance Quality Grade G6.3 for the rotating assembly of fan and motor. Balance readings are to be made electronically in the axial, vertical and horizontal planes. The wheels shall not have any resonant conditions across the entire operating range.

E. The fans shall be secured to the motor shaft using taper lock bushings. Wheel hubs are to be machined aluminum. Wheels and hubs shall not require any finish coating.


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F. The motor shall meet or exceed EISA 2007 efficiencies. Motors are to be NEMA rated as [Open Drip Proof (ODP)] [Totally Enclosed Fan Cooled (TEFC)] with a 1.25 service factor.

2.06B Blower / Motor Assembly (Direct Drive Parallel Fans (DDP) 30 and 35 ton single or 60 and 70 ton dual)

A. Units with the Direct Drive Parallel Fan (DDP) system shall consist of dual fans in each module. A single VFD shall be used to drive the dual fans and shall not have any speeds blocked out.

B. The blower assembly shall be direct driven non-overloading type backward inclined unhoused fans. The fan shall incorporate a corrosion resistant aluminum impeller with extruded airfoil shaped blades which are continuously welded. The front panel shall have a removable inlet cone.

C. Blower assemblies shall be mounted on a heavy-gauge galvanized steel frame and front panel. The design shall insure structural integrity of the base to minimize any vibration. The motor base shall insure proper alignment to the fan wheel, motor and inlet cone.

D. The fans shall be dynamically balanced as a complete unit in accordance with ISO 1940, to achieve Balance Quality Grade G6.3 for the rotating assembly of fan and motor. Balance readings are to be made electronically in the axial, vertical and horizontal planes. The wheels shall not have any resonant conditions across the entire operating range.

E. The fans shall be secured to the motor shaft using taper lock bushings. Wheel hubs are to be machined aluminum. Wheels and hubs shall not require any finish coating.

F. The motor shall meet or exceed EISA 2007 efficiencies. Motors are to be NEMA rated as [Open Drip Proof (ODP)] [Totally Enclosed Fan Cooled (TEFC)] with a 1.25 service factor.

2.07 Electrical System

A. The electrical system shall conform to National Electric Code (NEC) requirements.


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B. Power connection shall be through the side of the unit to power terminal block(s). Single point power connection shall be used for all cooling only applications or cooling / heating units having less than 50 kW of electric heat.

C. All controls shall be 24 volts and shall be factory mounted and wired, except as noted.

D. All electrical components (blower motors, compressors, electric heat stages, etc.) shall have individual definite purpose contactors.

E. Each component shall be safety agency listed as required. All components shall be identified to co-ordinate with the wiring diagram provided.

F. The control panel shall be isolated so that access can be made without disrupting unit operation. The hinged control panel door shall have tool operated latches.

2.08 Evaporator Air Filtration

A. The filter frame shall be mounted directly to the unit and shall be accessible from either side. Slides shall be provided within the filter frame for easy removal of all the filters. Filters shall also be able to be removed or installed from the face of the filter frame for those units that do not incorporate a return air duct.

B. Evaporator air filters shall be nominal 2” depth pleated, throwaway type panel filters consisting of cotton and synthetic or synthetic only media with galvanized expanded metal backing and moisture resistant enclosing frame. The filter shall be classified for flammability by Underwriters Laboratories, Inc. as Class 2.

B. The filter media shall have an efficiency of MERV 8 [11] [13] based on ASHRAE test standard 52.2.

C. The filter face area shall contain not less than 10 pleats per lineal foot. Media support shall be heavy gauge expanded, electro-galvanized metal with grid members being no less than 0.025”wide, providing an open area of not less than 96%. The grid shall be 100% bonded to the media on the air exiting side to eliminate media vibration and pull-away. The grid shall be formed to provide a uniform V-shaped pleat with the open area on the air exiting matched to the open area on the air entering side for maximum utilization of the media and low airflow resistance. The enclosing frame shall be constructed of a rigid, high wet strength board.


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2.09 Controls

A. The unit shall contain a factory mounted variable frequency drive (VFD), pulse width type, to control the blower speed. The VFD shall be isolated from high voltage and electrical noise by being placed into its own ventilated compartment. The VFD shall control motor speed based on duct static pressure.

B. The blower motor shall be controlled by a contactor that breaks all phases of power. The contactor shall provide power to the blower motor through an external overload device.

C. A field mounted duct static pressure transducer shall be provided by the factory. The transducer shall provide a signal for control of the blower speed. The location and connection shall be as determined by the manufacturer and mechanical designer recommendations.

D. A manual reset High Duct Static Pressure Sensor shall be provided by the factory. This control shall be field adjusted to 1” higher than the control static pressure and will stop unit operation should the duct static pressure exceed this value. Suitable field supplied tubing is to be run from the sensor back to the unit.

E. Each compressor shall be provided with its own contactor that breaks all phases of power. The microprocessor control shall provide anti-short cycle protection for each compressor. The refrigerant circuits shall be protected with high and low pressure switches. Upon opening, a signal will be provided to the microprocessor for an alarm signal and the unit will be shut down. The standard air flow proving switch must be satisfied before the compressors can be started.

F. Where two compressors make up a stage of cooling, a time delay shall be incorporated into the controls to delay the start of the second compressor.

G. A factory installed dirty filter switch shall be provided in the unit. This shall be a pressure differential type switch that is set to read across the filter bank provided. When the set point is exceeded a signal will be provided to the microprocessor for an alarm signal.


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H. A factory installed drain pan overflow switch shall be provided. This device will sense an above normal condensate level and send a signal to the microprocessor. This will shut the unit down and provide an alarm signal.

I. Contact terminals - Contact terminals are to be provided for remote On / Off, Common Alarm, or other conditions or functions as desired.

J. Dry Contacts - Unit shall include [1] [2] [3] set(s) of dry electrical contacts for field connection to auxiliary devices furnished by others.

K. Water Flow Switch - A field supplied and installed water flow switch shall be included in the unit controls. If adequate water flow is not proven, the controls shall not allow system operation. An alarm shall be enunciated. The water flow switch shall be wired to factory mounted terminals.

L. Freezestat - Factory installed freezestats shall be included. The freezestats shall be fully encapsulated, automatic reset type, clamped to each compressor suction line. Upon opening, the compressor shall be shut down and the blower shall continue to run until the freezestat resets.

M. 3 Contactor VFD Bypass - Units with a DWDI blower shall have a factory installed 3 contactor VFD bypass switch. Switch shall allow unit to run through the VFD in the AUTO position and as a constant volume unit while in the MANUAL position.

N. Firestat - A factory supplied firestat shall be shipped loose for field installation. Device shall be a manual reset, adjustable setting, type which is to be field installed in the [supply] [return] air stream and wired to the unit electrical control panel. Upon activation, this control will terminate system operation.

O. Smoke Detector - A factory supplied smoke detector shall be shipped loose for field installation in the [supply] [return] air duct and wired to the unit electrical control panel. Upon activation, this control will terminate system operation.

P. pLAN Network – Microprocessor controls shall be configured to network multiple units together. Factory installed terminals shall be provided in each unit.

Q. Condensate Pump - A condensate pump for the automatic collection and removal of condensate from the unit. Pump shall be shipped loose for field mounting. Pump shall consist of a 1/30 H.P. high performance motor, a ½ gallon ABS housing and cover, ABS collection tank, vertical centrifugal pump with glass-


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filled polypropylene impeller and stainless steel shaft, check valve, power cord and automatic controls.

A separate 115-1-60 power supply for the condensate pump is to be field-provided.

R. Phase Reversal Sensor - Unit shall include a factory-mounted and wired phase reversal sensor.

S. Air Side Economizer - An air side economizer control package shall be provided by the unit manufacturer. Air side economizer control package shall include an economizer control module, outdoor air enthalpy sensor, return air enthalpy sensor, mixed air temperature sensor and a supply air temperature sensor. Unit mounted terminal blocks shall be provided for field wiring of sensors.

1. The unit(s) shall be provided with an air side economizer. Air side economizer controls shall be factory supplied and field installed.

2. The air side economizer return air dampers and outside air dampers and associated actuators shall be field supplied. Actuators shall be spring return type.

3. Air side economizer shall [be a field fabricated box with dampers attached to the unit inlet air opening] [utilize the mechanical room as a return air plenum].

4. The air side economizer shall be activated when the outside air conditions of enthalpy and temperature can satisfy the cooling requirements. The outside air dampers and return air dampers shall be modulated to control the inlet air for the cooling load requirement. Mechanical cooling can be enabled as an assist to the air side economizer if it is full open and the cooling load is not being satisfied.

2.10 Microprocessor Controls

A. The unit shall contain the MarvelTM Plus self-contained programmable microprocessor controller. The factory mounted controller shall include the following:

a. An 8 line by 22 character white backlit LCD screen display [shipped loose for field wall mounting] [factory unit mounted (external)].

b. English Text


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c. System Status Displayd. Active Temperature Displaye. 6 Button Navigation / Submenuf. Manual control from the controller keypad.g. Password protection (Optional)h. Automatic restart from a loss of poweri. Real Time Clock (back up of clock during power outage)j. 7 Day Occupied / Unoccupied Period Programmabilityk. Night Set Back / Up Capabilityl. Auto Daylight Savings Timem. BACnet™, LonWorks® & Modbus compatibilityn. Return Air Temperature Sensoro. Supply Air Temperature Sensorp. Duct Static Pressure Transducerq. Air Pressure Switch (High Static) inputr. High & Low Refrigerant Pressure Safety Switch Inputss. Anti-short Cycle Protectiont. 4 MB Flash memoryu. 10 Analog inputsv. 18 Digital inputsw. 6 Analog outputsx. 18 Digital outputsy. Plastic housing shall be DIN Rail mountedz. Plug-In Screw Down Type connectorsaa. Alarm history (Up to 50 alarms)bb. System Enables Menucc. Time Clock Menudd. Alarm Set Point Menuee. Equipment Run Hours Menuff. Set Point Menugg. Technician Menuhh. Factory Menuii. Unit shall include 100’ of cable for connection of wall display to unit

mounted microprocessor.jj. Microprocessor shall include BMS Interface [BACnet™] [ModBus]

[LonWorks®]kk. pLAN Network capability (Optional)

B. The unit shall provide the following visual and audible alarms

a. High duct static pressureb. High Refrigerant Pressure (each compressor)c. Low Refrigerant Pressure (each compressor)d. Loss of Air Flow


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e. Evaporator Motor Overloadf. High Supply Air Temperatureg. Low Supply Air Temperatureh. High Return Air Temperaturei. Low Return Air Temperaturej. Dirty Filterk. Drain Pan Overflowl. Sensor Failurem. Loss of Water Flow (Optional)n. Smoke Detector (Optional)o. Firestat (Optional)p. Heater High Limit (Optional)

2.11 System OptionsA. Electric Heat - Unit shall include a factory-mounted nichrome open-wire heater

assembly with a contactor on each stage and safety limit control. Electric heater shall have the heat capacity as listed in the equipment schedule. Each stage shall have a circuit breaker.

On heaters with multiple banks within a stage of heat, a time delay shall be incorporated to assure that only one bank of heat is activated at one time.

An automatic reset high limit thermal device shall be incorporated into the controls to deactivate the heaters in the event of a high supply air temperature.

B. SCR - The electric heating coil shall be controlled through a silicon controlled rectifier (SCR) with an extruded aluminum heat sink and solid state logic control system. The microprocessor shall provide vernier control.

C. Hot Water Coil - Unit shall include a factory-mounted aluminum fin, copper tube Hot Water Heating Coil. Hot Water Coil capacity shall be as shown on the equipment schedule.

D. Hot Water Coil Valve - Hot Water Coil valve shall be factory supplied, shipped loose, for field installation. Valve shall be suitable for 150 psig, or less, applications and shall be a 2-way, on/off type.

E. Chilled Water Coil - Unit shall include a factory-mounted aluminum fin, copper tube Chilled Water Coil. Chilled Water Coil capacity shall be as shown on the equipment schedule.


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F. Chilled Water Coil Valve - Chilled Water Coil valve shall be factory supplied, shipped loose, for field installation. Valve shall be suitable for 150 psig, or less, applications and shall be a 2-way, on/off type.

G. Steam Coil - Unit shall include a factory-mounted aluminum fin, copper tube Distributed (non-freeze) Steam Heating Coil. Steam Coil capacity shall be as shown on the equipment schedule. Steam coil shall be suitable for low pressure steam, less than 10 psig. Steam piping, trap, control valve and actuator shall be field supplied and installed.

H. Water Side Economizer - The unit shall be provided with a water side economizer. Water side economizer coil shall be made with heavy wall seamless copper tubes mechanically expanded to aluminum fins with self- spacing collars. System shall incorporate a 2-way valve along with a water inlet temperature sensor. The water side economizer discharge piping shall be routed to the condenser heat exchangers. The mechanical cooling shall be able to operate concurrent with the water side economizer.

I. Heresite Coil Coating – [Evaporator], [Hot Water], [Water Side Economizer] [Chilled water Coil] finned tube coil(s) shall be protected with a pure Phenolic thermosetting resinous coating. Metal preparation to provide a surface profile shall include degreasing and etching or phosphatizing by immersion. The coating shall be applied in multiple coats by immersion. After each coat immersion, the coating shall be partially cured in an oven. Following the final immersion and application of (1) spray coat, the coating shall be totally cured in an oven.

The total Dry Film Thickness of the coating shall be approximately 2 mils, thereby providing good protection without adversely affecting heat transfer. Dry Film Thickness varies depending upon fin spacing and the number of tubes and rows in depth. The coating shall withstand dry heat up to 205 Deg. C (400 Deg. F) and show no sign of attack after 3000 hours of salt spray test to A.S.T.M. Specification B117.

The coating shall be Heresite P-413C baked Phenolic with plasticizer or approved equal.

I. Electro-Coil Coating – [Evaporator], [Hot Water], [Water Side Economizer] [Chilled Water Coil] finned tube coil(s) shall be protected with a flexible cationic epoxy electrocoat uniformly applied to all coil surface areas without material bridging between fins. Coating process of complete immersion and computer


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controlled cathodic deposition shall ensure complete coil encapsulation and a uniform dry film thickness of 0.001” (one mil) on all surface areas including fin edges. Coil protection shall not adversely affect heat transfer by more than 1%.

Coating shall exhibit superior hardness characteristics of 2H minimum per ASTM D3363 and a cross-hatch adhesion of 4B-5B per ASTM B3359. Direct impact resistance shall be up to 100 in-lb. per ASTM D2794. Humidity and water immersion resistance shall be up to a minimum 500 and 250 hours respectively (ASTM D1735 and ASTM D870). Corrosion durability shall be confirmed through testing to no less than 3000 hours salt spray per ASTM B117. The coating shall have temperature resistance up to 400 degrees F.

The coating shall be E-Coat or approved equal.

Part 3 – Factory Testing

3.1 Functional Run Test

A. Each complete system shall be functionally run-tested prior to shipment. A dielectric withstand test shall also be conducted. All data is to be recorded on a factory test form and shall include all electrical components, motors, compressors, safeties, controls, along with refrigerant pressure and electrically operated options.

B. Each refrigerant circuit shall have a complete refrigerant circuit leak test and all data is to be included in the factory test form(s).

C. A final inspection prior to shipment is also to be conducted and documented.

Part 4 - Execution

4.1 Installation, Operation and Maintenance

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

B. Installing contractor shall install unit in accordance with industry accepted practices and Installation, Operation and Maintenance Manual.

C. Industry accepted start-up procedures and requirements shall be complied with to ensure safe and reliable operation of the unit.
