HVAC Salient Characteristics.pdf

HVAC Salient Characteristics

OPERATING VOLTAGE: Shall be 208/230/3PH.

CAPACITY: Capacity shall be 10 Tons nominal

QTY Requested: Two (2)

Evaporator fan compartment:

a. Interior cabinet surfaces shall be insulated with a minimum 1/2 in. thick, minimum 1-1/2 lb density, flexible fiberglass insulation bonded with a phenolic binder, neoprene coated on the air side.

b. Evaporator fan compartment interior cabinet insulation shall conform to AHRI Standards 340/360 minimum exterior sweat criteria.

c. Aluminum foil-faced fiberglass insulation shall be used in the heat compartment.

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

Electric Heat Compartment:

a. Aluminum foil-faced fiberglass insulation shall be used.

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

Control System for HVAC:

a. Shall be complete with self-contained low-voltage control circuit protected by a resettable circuit breaker on the 24-v transformer side.

b. Transformer shall have 75VA capability.

c. Shall utilize color-coded wiring.

d. Shall include a Unit Control Board to conveniently and safely provide connection points for vital control functions such as: smoke detectors, phase monitor, economizer, thermostat, and low- and high-pressure switches.

Controller shall also provide an intuitive means to adjust the indoor fan speed through a simple switch and pot adjustment design.

e. Unit shall include a minimum of one 8-pin screw terminal connection board for connection of control wiring.

Demand Defrost:

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

b. 30, 60, 90, 120-minute timer shall activate the defrost cycle only if the coil temperature is low enough to indicate a heavy frost condition.

c. Defrost cycle shall terminate when defrost thermostat is satisfied and shall have a positive termination time of 10 minutes.

d. Defrost Cycle Indicator LED.

e. Dip switch selectable defrost time between 30, 60, 90 and 120 minutes. Factory set at 30 minutes.

f. Molded plug connection to ensure proper connection.

Safeties:

a. Compressor over-temperature, over-current. High internal pressure differential.

b. Low pressure switch shall use different color wire than the high-pressure switch. The purpose is to assist the installer and service technician to correctly wire and or troubleshoot the rooftop unit.

c. High pressure switch shall use different color wire than the low-pressure switch. The purpose is to assist the installer and service technician to correctly wire and or troubleshoot the rooftop unit.

d. Automatic reset, motor thermal overload protector.

Panel Air Filters:

a. Shall consist of factory installed, low velocity, disposable 2-in. thick fiberglass filters of commercially available sizes.

b. Unit shall use only one filter size. Multiple sizes are not acceptable.

c. Filters shall be accessible through an access panel with “no-tool” removal as described in the unit cabinet section of this specification.

d. Filters shall be held in place by a pivoting filter tray, facilitating easy removal and installation.

Quality Assurance:

a. Unit meets ASHRAE 90.1 minimum efficiency requirements.

b. Unit shall be rated in accordance with AHRI Standards 340/360.

c. Unit shall be designed to conform to ASHRAE 15.

d. Unit shall be UL-tested and certified in accordance with ANSI Z21.47 Standards and UL-listed and certified under Canadian standards as a total package for safety requirements.

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

f. Unit casing shall be capable of withstanding 500-hour salt spray exposure per ASTM B117 (scribed specimen).

g. Unit shall be designed in accordance with ISO 9001 and shall be manufactured in a facility registered by ISO 9001:2015.

h. Unit shall be subjected to a completely automated run test on the assembly line. The data for each unit will be stored at the factory and must be available upon request.

i. Unit shall be designed in accordance with UL Standard 1995, including tested to withstand rain.

j. Unit shall be constructed to prevent intrusion of snow and tested to prevent snow intrusion into the control box up to 40 mph.

k. Unit shake tested to assurance level 1, ASTM D4169 to ensure shipping reliability.

Ambient Max Temp Start:

a. Unit shall be capable of starting and running at 125°F (52°C) ambient outdoor temperature meeting maximum load criteria of AHRI Standard 340/360 at ±10% voltage.

Construction:

a. Unit cabinet shall be constructed of galvanized steel and shall be bonderized and coated with a prepainted baked enamel finish on all externally exposed surfaces.

b. Unit cabinet exterior paint shall be: film thickness, (dry) 0.003 in. minimum, gloss (per ASTM D523, 60°F/16°C):

60, Hardness: H-2H Pencil hardness.

c. Unit shall have base rails on a minimum of 2 sides.

d. Holes shall be provided in the base rails for rigging shackles to facilitate maneuvering and overhead rigging.

e. Holes shall be provided in the base rail for moving the rooftop by fork truck.

f. Base rail shall be a minimum of 16-gauge thickness.

g. Cabinet panels shall be easily removable for servicing.

h. Unit shall have one factory installed, toolless, removable, filter access panel.

i. Panels covering control box, indoor fan, indoor fan motor, gas components (where applicable), and compressors shall have molded composite handles.

j. Handles shall be UV modified, composite. They shall be permanently attached and recessed into the panel.

k. Screws on the vertical portion of all removable access panel shall engage into heat resistant, molded composite collars.

l. Collars shall be removable and easily replaceable using manufacturer recommended parts.

Refrigerant Coils:

a. Standard evaporator and condenser coils shall have aluminum lanced plate fins mechanically bonded to seamless internally grooved copper tubes with all joints brazed.

b. Evaporator coils shall be leak tested to 150 psig, pressure tested to 450 psig, and qualified to UL 1995 burst test at 1775 psig.

c. Condenser coils shall be leak tested to 150 psig, pressure tested to 650 psig, and qualified to UL 1995 burst test at 1980 psig.

d. Shall have a durable epoxy-phenolic coating to provide protection.

e. 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.

f. Epoxy-phenolic barrier shall minimize galvanic action between dissimilar metals.

g. Corrosion durability of fin stock shall be confirmed through testing to be no less than 1000 hours salt spray per

ASTM B117-90.

e. Corrosion durability of fin stock shall be confirmed through testing to have no visible corrosion after 48-hour immersion in a room temperature solution of 5% salt, 1% acetic acid.

f. Fin stock coating shall pass 2000 hours of the following: one week exposure in the prohesion chamber followed by one week of accelerated ultraviolet light testing. Prohesion chamber: the solution shall contain 3.5% sodium chloride and 0.35% ammonium sulfate. The exposure cycle is one hour of salt fog application at ambient followed by one hour drying at 95°F (35°C).

g. Shall have a flexible epoxy polymer coating uniformly applied to all coil surface areas without material bridging between fins.

h. Coating process shall ensure complete coil encapsulation of tubes, fins and headers.

i. Color shall be high gloss black with gloss per ASTM D523-89.

j. Uniform dry film thickness from 0.8 to 1.2 mil on all surface areas including fin edges.

k. Superior hardness characteristics of 2H per ASTM D3363-92A and crosshatch adhesion of 4B-5B per ASTM D3359-93.

l. Impact resistance shall be up to 160 in.-lb (ASTM D2794-93).

m. Humidity and water immersion resistance shall be up to minimum 1000 and 250 hours respectively (ASTM D2247-92 and ASTM D870-92).

n. Corrosion durability shall be confirmed through testing to be no less than 1000 hours salt spray per ASTM B117- 90.

Refrigerant:

a. Outdoor, rooftop mounted, electrically controlled, heating and cooling unit utilizing a fully hermetic scroll compressor(s) for cooling duty and heat pump heating duty.

b. Unit shall use R-410A refrigerant.

c. Thermostatic Expansion Valve (TXV) shall help provide optimum performance across the entire operating range.

Shall contain removable power element to allow change out of power element and bulb without removing the valve body.

d. Refrigerant filter drier - Solid core design.

e. Service gauge connections on suction and discharge lines.

f. Pressure gauge access through a specially designed access port in the top panel of the unit.

g. Suction line accumulator to provide protection in all operating modes from cooling, heating and reverse cycle switching.

h. There shall be gauge line access port in the skin of the rooftop, covered by a black, removable plug. This gauge access port shall facilitate correct and accurate condenser pressure readings by enabling the reading with the compressor access panel on.

i. Unit shall use 2 tandem scroll compressors on single independent refrigeration circuit.

j. Units shall have single circuit and 2 stage cooling and contain 2 dual stage compressors.

k. Evaporator coils shall be a full active design to help better control comfort latent removal.

l. Compressor motors shall be cooled by refrigerant gas passing through motor windings.

m. Compressors shall be internally protected from high discharge temperature conditions.

n. Compressors shall be protected from an over-temperature and over-amperage conditions by an internal, motor overload device.

o. Compressor shall be factory mounted on rubber grommets.

p. Compressor motors shall have internal line break thermal, current overload and high-pressure differential protection.

q. Crankcase heaters shall not be required for normal operating range, unless required by compressor manufacturer due to refrigerant charge limits.

r. Compressors shall be a 2 stage cooling capacity design.

Evaporator Fan:

a. Shall be a ECM motor design.

b. Shall have permanently lubricated bearings.

c. Shall have inherent automatic-reset thermal overload protection.

d. Shall have slow ramp up to speed capabilities.

e. Shall require no fan/motor belts for operation, adjustments and or initial fan speed set up.

f. Fan DC voltage set up on Unit Control Board can eliminate the need of removal of blower access door, required on conventional belt drive systems.

g. Shall be internally protected from electrical phase reversal and loss.

h. Shall be easily set with dedicated selection switch and adjustment pot on unit control board.

i. Shall provide 2 stage cooling capacity control, the indoor fan speed is automatically controlled to meet the code-compliant <66% low fan speed and 100% at full fan speed operation.

j. Blower fan shall be a Vane Axial fan design with 75% less moving parts than a conventional belt drive system.

k. Shall be constructed of a cast aluminum stator and high impact composite material on stator, rotor and air inlet casing.

l. Shall be a patented/pending design with a corrosion resistant material and dynamically balanced.

m. Shall have slow ramp up to speed capabilities to help reduce sound and comfort issues typically associated with single speed belt drive systems.

n. Shall be a slide out design with removal of a few support brackets.

o. Shall include an easily accessible Unit Control Board to conveniently and safely provide connection points for vital control functions such as: smoke detectors, phase monitor, economizer, thermostat, and low- and high-pressure switches. Controller shall also provide an intuitive means to adjust the indoor fan speed through a simple switch and pot adjustment design.

Condenser Fans Motors:

a. Shall be a totally enclosed motor.

b. Shall use permanently lubricated bearings.

c. Shall have inherent thermal overload protection with an automatic reset feature.

d. Shall use a shaft-down design on all sizes.

Condenser Fan Blades:

a. Shall be a direct-driven propeller type fan constructed of high impact composite material.

b. Shall have high impact composite blades completely formed into one piece without blade fasteners or connectors and shall be dynamically balanced.

Phase Protection:

a. Shall monitor the sequence of 3 phase electrical system to provide a phase reversal protection.

b. Shall monitor the 3 phase voltage inputs to provide a phase loss protection for the 3-phase device.

c. Will work on either a Delta or Wye power connection.

Electric Heat:

a. Heater element open coil resistance wire, nickel-chrome alloy, 0.29 inches inside diameter, strung through ceramic insulators mounted on metal frame. Coil ends are staked and welded to terminal screw slots.

b. Heater assemblies are provided with integral fusing for protection of internal heater circuits not exceeding 48 amps each. Auto reset thermo limit controls, magnetic heater contactors (24 v coil) and terminal block all mounted in electric heater control box (minimum 18 ga galvanized steel) attached to end of heater assembly.

c. Shall be 16 KW Nominal.