SECTION 15781

PACKAGED ROOF TOP AIR CONDITIONING UNITS

PART 1 GENERAL

SECTION INCLUDES

Packaged roof top unit.

Unit controls.

Remote panel.

Roof mounting frame and base.

Maintenance service.

PRODUCTS FURNISHED BUT NOT INSTALLED UNDER THIS SECTION

Section [_____ - __________:] Placement and installation of roof mounting frames.

Section 15952 - Controls and Instrumentation: Installation of thermostats and other controls components.

Section 16180 - Equipment Wiring Systems: Installation and wiring of thermostats and other controls components.

Section 16180 - Equipment Wiring Systems: Final connection of wiring from unit terminal strip to remote panel.

RELATED SECTIONS

Section 15170 - Motors: Evaporator [and condenser] fan motors.

Section 15242 - Vibration Isolation.

Section 15290 - Ductwork Insulation: Duct liner.

Section 15885 - Air Cleaning.

Section 15952 - Controls and Instrumentation: Control components, time clocks.

Section 16180 - Equipment Wiring Systems: Electrical supply to units.

REFERENCES

ANSI/NFPA 90A - Installation of Air Conditioning and Ventilation Systems.

ARI 210 - Unitary Air-Conditioning Equipment.

ARI 240 - Air Source Unitary Heat Pump Equipment.

ARI 270 - Sound Rating of Outdoor Unitary Equipment.

SUBMITTALS

Submit [shop drawings and] product data under provisions of Section [01300.] [01340.]

Submit [shop drawings and] product data for manufactured products and assemblies required for this project.

Indicate electrical service and duct connections on [shop drawings or] product data.

Submit manufacturer's installation instructions under provisions of Section [01300.] [01340.]

OPERATION AND MAINTENANCE DATA

Submit operation and maintenance data under provisions of Section [01700.] [01730.]

Include manufacturer's descriptive literature, operating instructions, installation instructions, maintenance and repair data, and parts listing.

DELIVERY, STORAGE, AND HANDLING

Deliver products to site under provisions of Section [01600.] [01610.]

Store and protect products under provisions of Section [01600.] [01620.]

Protect units from physical damage by storing off site until roof mounting frames are in place, ready for immediate installation of units.

WARRANTY

Provide [five] [_____] year [manufacturer's] warranty under provisions of Section [01700.] [01740.]

Warranty: Include coverage of [refrigeration compressors.] [heat exchangers.] [_______________.]

MAINTENANCE SERVICE

Furnish complete service and maintenance of packaged roof top units for [one] [_____] year from Date of Substantial Completion.

Provide maintenance service with a two month interval as maximum time period between calls. Provide 24-hour emergency service on breakdowns and malfunctions.

Include maintenance items as outlined in manufacturer's operating and maintenance data, including minimum of six filter replacements, minimum of one fan belt replacement, and controls check-out, adjustments, and recalibrations.

Submit copy of service call work order or report, and include description of work performed.

EXTRA MATERIALS

Provide [one] [_____] set of filters under provisions of Section [01700.] [01750.]

PART 2 PRODUCTS

MANUFACTURERS

[____________________________________________.]

[____________________________________________.]

[____________________________________________.]

Substitutions: Under provisions of Section [01600.] [01630.]

MANUFACTURED UNITS

Provide roof-mounted units having [gas burner][,][.] [electric heating elements][,][.] [and] [electric regrigeration.]

Unit shall be self-contained, packaged, factory assembled and prewired, consisting of cabinet and frame, supply fan, [return fan,] [heat exchanger and burner,] [electric heating elements,] controls, air filters[,][.] [refrigerant cooling coil and compressor, condenser coil and condenser fan.]

FABRICATION

Cabinet: [Steel] [Galvanized steel] with baked enamel finish, access doors or removable access panels with quick fasteners [screwdriver operated flush cam type.] [locking door handle type with piano hinges.] Structural members shall be minimum 18 gage (1.20 mm), with access doors or removable panels of minimum 20 gage (0.90 mm).

Insulation: [1/2] [one] [2] inch ([13] [25] [50] mm) thick neoprene coated glass fiber on surfaces where conditioned air is handled. Protect edges from erosion.

Heat Exchangers: [Aluminized] [Stainless] steel, of welded construction.

Supply [and Return] Fan: Forward curved centrifugal type, resiliently mounted with V-belt drive, [adjustable variable pitch motor pulley,] and rubber isolated hinge mounted motor[.] [or direct drive as indicated.] [Isolate complete fan assembly.] Refer to Section 15242.

Air Filters: [One inch (25 mm) thick permanent washable.] [One inch (25 mm) thick glass fiber disposable media in metal frames.] [2 inch (50 mm) thick glass fiber disposable media in metal frames.] [Automatic renewable media with extended surface media filters.] [Refer to Section 15885.]

Roof Mounting Frame: [14] [24] [_____] inches ([350] [610] [_____] mm) high galvanized steel, channel frame with gaskets, nailer strips.

BURNER

Gas Burner: [Atmospheric] [Induced draft] [Forced draft] type burner with adjustable combustion air supply, pressure regulator, gas valves, manual shut-off, intermittent spark or glow coil ignition, flame sensing device, and automatic 100 percent shut-off pilot.

Gas Burner Safety Controls: Energize ignition, limit time for establishment of flame, prevent opening of gas valve until pilot flame is proven, stop gas flow on ignition failure, energize blower motor, and after air flow proven and slight delay, allow gas valve to open.

High Limit Control: Temperature sensor with fixed stop at maximum permissible setting, de-energize burner on excessive bonnet temperature and energize burner when temperature drops to lower safe value.

Supply Fan Control: Temperature sensor sensing bonnet temperatures and independent of burner controls, or adjustable time delay relays with switch for continuous fan operation.

ELECTRIC HEATING COIL

[Finned tube heating elements] [or] [helical nickel-chrome resistance wire coil heating elements with refractory ceramic support bushings] easily accessible with automatic reset thermal cut-out, built-in [magnetic] [mercury] contactors, galvanized steel frame,] [control circuit transformer and fuse,] [manual reset thermal cut-out,] [airflow proving device,] [toggle switch (pilot duty),] [fused disconnect,] [unfused disconnect,] [load fuses.]

Controls shall start supply fan before electric elements are energized and continue operating until air temperature reaches minimum setting, with switch for continuous fan operation.

EVAPORATOR COIL

Provide copper [or aluminum] tube aluminum fin coil assembly with galvanized drain pan and connection.

Provide capillary tubes or thermostatic expansion valves for units of 6 tons (21 kw) capacity and less, and thermostatic expansion valves and alternate row circuiting for units 7.5 tons (26 kw) cooling capacity and larger.

COMPRESSOR

Provide hermetic or semi-hermetic compressor, 3600 rev/min maximum, resiliently mounted with positive lubrication, crankcase heater, high and low pressure safety controls, motor overload protection, suction and discharge service valves and gage ports, and filter drier.

Five minute timed off circuit shall delay compressor start.

Outdoor thermostat shall energize compressor above [35] [57] [_____] degrees F ([2] [14] [_____] degrees C) ambient.

Provide step capacity control by [hot gas by-pass.] [cycling compressors.] [cycling unloading.] [cycling multi-speed compressors.]

For heat pump units, provide reversing valve, suction line accumulator, [discharge muffler,] flow control check valve, and solid-state defrost control utilizing thermisters.

CONDENSER

Provide copper [or aluminum] tube aluminum fin coil assembly with subcooling rows.

Provide direct drive propeller fans, resiliently mounted with fan guard, motor overload protection, wired to operate with compressor.

Provide [refrigerant pressure switches] [outdoor thermostat] to cycle condenser fans.

SUPPLY/RETURN CASING

Dampers: Provide manual outside [and return] air dampers for fixed outside air quantity.

****** [OR] ******

Dampers: Provide remote controlled outside [and return] air dampers with damper operator and remote rheostat for adjusting outside air quantity.

****** [OR] ******

Dampers: Provide outside, return, and relief dampers with damper operator and control package to automatically vary outside air quantity. Outside air damper shall fall to closed position. [Relief dampers may be gravity balanced.]

Gaskets: Provide tight fitting dampers with edge gaskets[,][.] [maximum leakage 5 percent at 2 inches (500 Pa) pressure differential.]

Damper Operator: 24 volt with gear train sealed in oil[,][.] [with spring return on units 7.5 ton (26 kw) cooling capacity and larger.]

****** [OR] ******

Damper Operator: Pneumatic piston or gear driven type with spring return[.] [and pilot positioner.]

Mixed Air Controls: Maintain selected supply air temperature and return dampers to minimum position [on call for heating and] [above 57 degrees F (14 degrees C) ambient.] [above 75 degrees F (24 degrees C) ambient.] [when ambient air temperature exceeds return air temperature.] [when ambient air enthalpy exceeds return air enthalpy.]

OPERATING CONTROLS

Provide low voltage, adjustable thermostat to control [burner operation,] [heater stages in sequence with delay between stages,] [compressor and condenser fan,] and supply fan to maintain temperature setting.

Include system selector switch [(heat-off-cool)][,][.] [(off-heat-auto-cool)][,][.] [and fan control switch (auto-on).]

Provide double acting thermostat with minimum [_____] stage heating and [_____] stage cooling.

Provide single acting thermostat with minimum [_____] stage cooling.

Locate thermostat in [room as shown.] [supply air.] [return air.]

Provide remote mounted fan control switch (on-auto).

Provide low limit thermostat in supply air to [close outside air damper and] stop supply fan.

Provide night control energized by central time clock to [maintain lower thermostat setting,] [maintain night thermostat setting,] [lock out refrigeration,] [close outside air damper and open return air damper,] [stop supply air fan,] [set fan control switch to auto position,] for night and unoccupied operation. [Provide time delay to maintain outside air damper closed and return air damper open after switching to day and occupied operation.]

Provide remote readout panels containing signal lights indicating system status, [heating system failure,] [cooling system failure,] and dirty filters; check switches proving signal light operations; system on-off switch[,][.] [and cooling system on-off switch.]

Provide in panel a [manual 12 hour timer to override night control,] [7 day time clock for energizing night control,] [remote damper control,] [low limit manual reset,] [and] [remote thermostat temperature set point.]

OPERATING CONTROLS - SINGLE ZONE UNITS

Electric solid state microcomputer based room thermostat, located as indicated in service area with remote sensor located as indicated.

Room thermostat shall incorporate:

Automatic switching from heating to cooling.

Preferential rate control to minimize overshoot and deviation from set point.

Set-up for four separate temperatures per day.

Instant override of setpoint for continuous or timed period from one hour to 31 days.

Short cycle protection.

Programming based on weekdays, Saturday and Sunday.

Switch selection features including imperial or metric display, 12 or 24 hour clock, keyboard disable, remote sensor, fan on-auto.

Room thermostat display shall include:

Time of day.

Actual room temperature.

Programmed temperature.

Programmed time.

Duration of timed override.

Day of week.

System model indication: heating, cooling, auto, off, fan auto, fan on.

Stage (heating or cooling) operation.

Provide low limit thermostat in supply air to close outside air dampers and stop supply fan.

OPERATING CONTROLS - VARIABLE VOLUME UNITS

Temperature transmitter located in supply air shall signal electronic logic panel to control mixing dampers and cooling in sequence. Mixing section shall operate as first stage of cooling and revert to minimum outside air above approximately 75 degrees F (24 degrees C) as determined by enthalpy of return and outdoor air.

Control cooling by cycling compressors, cylinder unloading, and hot gas bypass.

Control logic shall allow supply air reset under low load or airflow conditions.

Seven day time clock with spring carry over (or electronic clock with battery backup) shall control unit on occupied/un-occupied schedule. At night, unit shall be off. Locate clock in remote control panel with status lights.

Provide two stage morning warm-up thermostat to hold outdoor dampers closed and energize heat until return air temperature reaches set point.

Provide within roof curb, by-pass dampers, bypassing air from supply fan discharge to return fan inlet to control duct static pressures. Control operation by sensing current to supply fan motor. Dampers shall equal performance of those specified in Section 15952.

OPERATING CONTROLS - FOOD STORE

Provide terminal strip on unit for connection of operating controls to remote panel by others. Control shall allow for [two] [_____] stages of heating and [two] [_____] stages cooling.

Control cooling by cycling compressors and cylinder unloading.

PERFORMANCE

[_____] Btu/hr ([_____] W) rated heating output with [_____] Btu/hr ([_____] W) heat input.

[_____] Btu/hr ([_____] W) rated heating output with [47 degrees F (8.3 degrees celsius) DB and 43 degrees fahrenheit (6.1 degrees Celsius) WB] [17 degrees Fahrenheit (-8.8 degrees Celsius) DB and 15 degrees Fahrenheit. (-9.4 degrees Celsius) WB] outdoor air temperature and 70 degrees Fahrenheit (21 degrees Celsius) air entering indoor coil, minimum co-efficient of performance [__________.]

[_____] Btu/hr ([_____] W) rated cooling output with [_____] degrees Fahrehnheit ([_____] degrees Celsius) DB and [_____] degrees Fahrenheit ([_____] degrees Celsius) WB air entering the evaporator, [_____] degrees Fahrenheit ([_____] degrees Celsius) DB condenser ambient air, minimum energy efficiency ration [_____.]

[_____] cfm ([_____] L/sec) supply air at [_____] inch wg ([_____] Pa) external static pressure.

[_____] cfm ([_____] L/sec) return air at [_____] inch wg ([_____] Pa) external static pressure.

Unit Sound Rating Number shall be maximum [_____.]

Scheduled performance is based on [ARI 210] [ARI 240] test conditions. [Sound Rating Numbers are in accordance with ARI 270.]

****** [OR] ******

Rated cooling capacity is based on [_____] degrees Fahrenheit ([_____] degrees Celsius) condenser ambient air.

Rated heating capacity is based on [47 degrees Fahrenheit (8.3 degrees Celsius) DB and 43 degrees Fahrenheit (6.1 degrees Celsius) WB] [17 degrees Fahrenheit (-8.3 degrees Celsius) DB and 15 degrees Fahrenheit (-9.4 degrees Celsius) WB] outdoor air temperature and 70 degrees Fahrenheit (21.1 degrees Celsius) air entering indoor coil.

Supply [and return] air is corrected to [_____] feet ([_____] m) altitude.

PART 3 EXECUTION

EXAMINATION

Verify that roof is ready to receive work and opening dimensions are as [indicated on shop drawings.] [illustrated by the manufacturer.]

Verify that proper power supply is available.

INSTALLATION

Install in accordance with manufacturer's instructions.

Mount units on factory built roof mounting frame providing watertight enclosure to protect ductwork and utility services. Install roof mounting frame level.

MANUFACTURER'S FIELD SERVICES

Provide initial start-up and shut-down during first year of operation, including routine servicing and check-out.

SCHEDULE

Drawing_Code	RT-1	RT-2

Location

Manufacturer

Model

Supply Fan

Air Flow

External Static Pressure

Fan Motor

Return Fan

Air Flow

Air Flow External Static Pressure

Fan Motor

Cooling

Sensible

Total

Evaporator Coil entering DB temp

Evaporator Coil entering WB temp

Evaporator Coil leaving DB temp

Evaporator Coil leaving WB temp

Condenser ambient air temp

Energy Efficiency Ratio

Heat

Input

Output

Outdoor DB Air Temp

Outdoor WB Air Temp

Co-efficient of Performance

Sound Rating Number

Compressor Power Input

Nominal Capacity (Tons)

END OF SECTION