Carrier NP034-074 specifications Service, Compressors

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When the ®rst-stage thermostat is satis®ed, ®rst-stage main gas valve and the pilot valve close. Induced-draft motor shuts off. Time-delay relay (built into constant volume control board) opens and timer sequence begins. When sequence is com- plete (after 110 ± 5 seconds) evaporator-fan motor shuts off.

48 Series High-Heat Units Ð Unit power on, thermostat sys- tem switch set at HEAT or AUTO. position, and fan switch set at AUTO. position.

First-stage thermostat (W1) calls for heat. Time-delay re- lay (built into constant volume control board), controlling evaporator fan, begins timer sequence (approximately 55 ± 10-second delay).

When time-delay sequence is complete, time-delay relay closes and evaporator fan starts.

When evaporator fan starts, air¯ow switch closes, closing induced draft contactor, and induced draft motor starts.

Centrifugal switch closes. Pilot valve opens, allowing gas to ¯ow to ®rst-stage pilot. Spark ignitor ignites pilot ¯ame. Sensor detects ¯ame, energizes main gas valve coil, and main gas valve opens. Gas ¯ows to main burners and ®rst-stage burners ignite. Spark ignitor shuts off and pilot remains on.

The spark ignitor will continue to spark for 90 seconds until pilot ¯ame is sensed. If the pilot fails to ignite or the sensor fails to detect ¯ame, the pilot valve closes and the spark ignitor shuts off for 300 seconds (5 minutes). During this time the induced draft motor remains on to purge any unburnt gas from the combustion tubes. This ignition se- quence will repeat inde®nitely.

When additional heat is needed, W2 is energized. Pilot valve no. 2 opens, allowing gas to ¯ow to second-stage pi- lot. Spark ignitor ignites pilot ¯ame. Sensor detects ¯ame, energizes main gas valve coil, and main gas valve no. 2 opens. Gas ¯ows to main burners and second-stage burners ignite. Second-stage spark ignitor shuts off. When the second-stage thermostat is satis®ed, W2 is deenergized and the second induced-draft motor and gas valve are shut off.

When the ®rst-stage thermostat is satis®ed, ®rst-stage main gas valve and the pilot valve close. Induced draft motor shuts off. Time-delay relay (built into constant volume control board) opens and timer sequence begins. When sequence is com- plete (after 110 ± 5 seconds) evaporator-fan motor shuts off.

50 Series Units Ð Unit power on, system selector switch set at HEAT position, fan switch set at AUTO. position.

On a call for heating, W1 on the thermostat closes, and evaporator fan and the ®rst stage of electric heat are ener- gized. On a further drop in room temperature, W2 on the thermostat closes, energizing the second stage of electric heat.

NOTE: Units equipped with low electric heat option have only one stage. Reset thermostat to a setting below room temperature. Electric heat and evaporator fan shut off.

COOLING, UNITS WITH ECONOMIZER Ð With sub- base switch set at COOL position and fan switch set at AUTO. position, evaporator fan is energized when Y1 on thermostat closes. If enthalpy is below setting on enthalpy switch, the economizer outdoor-air dampers will modulate open to sat- isfy the cooling requirement. If outdoor air alone will not meet the cooling requirements, Y2 on the thermostat will close energizing compressor no. 1 to work in conjunction with the modulating economizer to meet the cooling require- ment. While the unit is operating using outdoor air, com- pressor no. 2 cannot be energized. If enthalpy is above set- ting on enthalpy switch, the economizer outdoor-air dampers move to the minimum (ventilation) position, and condenser fan numbers 1 and 2 cycle on and off as described in Cool- ing, Units Without Economizer section on page 41.

NOTE: If fan switch is ON position and the room thermostat is satis®ed, the outdoor-air dampers move to the minimum position.

HEATING, UNITS WITH ECONOMIZER Ð Operation is the same as described in Heating, Units Without Econo- mizer sections on page 41, except that the outdoor-air damp- ers move to the minimum position on a call for heat.

VENTILATION-AIR CIRCULATION (Continuous Fan) Ð Turn unit power on. Set system selector switch at OFF, HEAT, or COOL position, and set fan switch at ON position.

Evaporator-fan contactor is energized through the switch on the thermostat and the evaporator fan runs continuously. The damper moves to the minimum position.

AUTOMATIC CHANGEOVER USING AUTOMATIC CHANGEOVER THERMOSTAT Ð Turn unit power on. Set system selector switch at AUTO. position.

When the temperature of the conditioned space rises to the cooling selector lever setting, unit automatically switches from heating to cooling mode. When the temperature of the conditioned space falls to the heating selector switch setting, unit automatically changes from cooling to heating mode. The thermostat is interlocked so that cooling and heating sys- tems do not operate at the same time.

Head Pressure Control Ð All units have a fan cy- cling thermostat which cycles the no. 2 condenser fan. This switch opens at 60 F ± 3° F and closes at 70 F ± 3° F. This allows the unit to operate down to 45 F outdoor ambient temperature.

NOTE: Accessory −20 F Low Ambient Kit is available, which allows mechanical cooling to −20 F outdoor ambient. See accessory installation instructions for mounting and opera- tion details.

SERVICE

Service Access Ð All unit components can be reached through clearly labeled hinged access doors. These doors are not equipped with tiebacks, so if heavy duty servicing is needed, either remove them or prop them open to prevent accidental closure.

Each door is held closed with 3 latches. The latches are secured to the unit with a single 1/4-in. 220 x 1/2-in. long bolt. See Fig. 33.

To open, loosen the latch bolt using a 7/16-in. wrench. Pivot the latch so it is not in contact with the door. Open the door. To shut, reverse the above procedure.

NOTE: Disassembly of the top cover may be required under special service circumstances. It is very important that the orientation and position of the top cover be marked on the unit prior to disassembly. This will allow proper replace- ment of the top cover onto the unit and prevent rainwater from leaking into the unit.

IMPORTANT: After servicing is completed, make sure door is closed and relatched properly, and that the latches are tight. Failure to do this can result in water leakage into the indoor-air section of the unit.

COMPRESSORS

Sizes 034 and 044 Ð Access to the compressors is through the doors on the condenser end of the unit. This door also provides access to the discharge and suction service valves, the crankcase heaters, and the high- and low-pressure switches. Compressor no. 1 is always the compressor on the left when facing main control box.

Sizes 054-074 Ð The oil pump end (compressor access) of each compressor is readily accessible from sides of unit as shown in Fig. 17. Access the motor end of the compressor through the condenser end of the unit or by removing compressor.

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Contents Installation, Start-Up Service Instructions Contents GeneralRigging Label Ð Physical Data 034, 044 Units Ð Physical Data 054-074 Units Operating Weights of Options and Accessories Weight Distribution and Center of GravityÐ Roof Curb 034, 044 Units Ft-inÐ Roof Curb 054-074 Units DegÐ Condenser Section Roof Curb 054-074 Units Only 054,064 270 105¤8 074 255 101¤16Economizer Settings Install Outdoor HoodsOutdoor-Air Inlet Adjustments Unit Sizes 034Unit Size Weight Ð Base Unit Dimensional Drawing 50DJ,DK,NP034,044 Units 8700 3946 5969 19-7 6717 Ð Base Unit Dimensional Drawing 50DJ,DK,NP054-074 Units Weight Ft-inDrain Location Selection Approx Deg AT 50% RHField Wire Routing Field Electrical ConnectionsField Power Wiring Connections Electrical Data, 034 Units 93.8 110 10.0 15.2 99.4 125 15.0 22.0 106.2 90.8 110 10.0 15.2 96.4 125 15.0 22.0 103.211.0 81.2 100 10.0 14.0 84.2 11075.6 10.0 12.2 80.0 100 15.0 18.0 85.8 73.6 10.0 12.2 78.0 100 15.0 18.0 83.865.8 67.8Electrical Data, 044 Units 109.5 125 10.0 15.2 115.1 15.0 22.0 121.9 150 106.5 125 10.0 15.2 112.1 15.0 22.0 118.9 15011.0 96.9 125 10.0 14.0 99.9 12586.1 110 10.0 12.2 90.5 15.0 18.0 96.3 84.1 110 10.0 12.2 88.5 15.0 18.0 94.376.3 100 10.0 11.0 78.3 100Electrical Data, 054 Units 10.0 15.2 150.8 200 15.0 22.0 157.6 20.0 28.0 163.6 10.0 15.2 144.8 175 15.0 22.0 151.6 200 20.0 28.0 157.615.0 21.0 129.6 175 20.0 27.0 135.6 17510.0 12.2 121.5 150 15.0 18.0 127.3 20.0 22.0 131.3 10.0 12.2 116.5 150 15.0 18.0 122.3 20.0 22.0 126.315.0 17.0 104.3 125 20.0 22.0 109.3 125Electrical Data, 064 Units 10.0 15.2 166.8 200 15.0 22.0 173.6 20.0 28.0 179.6 225 10.0 15.2 160.8 200 15.0 22.0 167.6 20.0 28.0 173.615.0 21.0 145.6 175 20.0 27.0 151.6 20010.0 12.2 131.8 150 15.0 18.0 137.6 175 20.0 22.0 141.6 10.0 12.2 126.8 150 15.0 18.0 132.6 20.0 22.0 136.6 17515.0 17.0 114.6 150 20.0 22.0 119.6 150Electrical Data, 074 Units 10.0 15.2 188.0 250 15.0 22.0 194.8 20.0 28.0 200.8 10.0 15.2 182.0 225 15.0 22.0 188.8 250 20.0 28.0 194.815.0 21.0 166.8 225 20.0 27.0 172.8 22510.0 12.2 151.0 200 15.0 18.0 156.8 20.0 22.0 160.8 10.0 12.2 146.0 175 15.0 18.0 151.8 200 20.0 22.0 155.815.0 17.0 133.8 175 20.0 22.0 138.8 175Field Control Thermostat Wiring Field Wiring for Building Pressurization and Smoke Purge Installing Flue/Inlet Hoods 48 Series Units Only Gas Piping DetailsFlue Hood PRE-START-UP Gas Manifold Pressure 48 Series Units Only Ð Field-Supplied Evaporator-Fan Pulley Data, 034,044 UnitsÐ Field-Supplied Evaporator-Fan Pulley Data, 054-074 Units Air Quantity Limits cfmInitial Check GeneralHEATING, Units Without Economizer Service CompressorsLiquid Service VALVES, Filter DRIERS, and Sight Glasses Power Exhaust MOTORS, PULLEYS, and BeltsEVAPORATOR-FAN MOTORS, PULLEYS, and Belts Burner Section Detail 48 Series Units Only Modulating Power Exhaust Damper Motor LubricationAdjustments Belt Installation and TensioningCondenser FAN Adjustment Pulley Alignment Charging Chart, 044 Units System One Condenser Fan Running Charging Chart, 064 Units System All Condenser Fans Running Auxiliary Switch Stroke Adjustment Main Burner Removal 48 Series Units OnlyProtective Devices Compressor ProtectionEconomizer Motor Checkout Electric Heat 50 Series Units OnlyGas Heat 48 Series Units Only Economizer Control Board Checkout TestDetailed Check Control Board Component Arrangement Page Compressor Lockout Connections ACC Gas Heat Sections 48DJ,NP034,044 Units Gas Heat Sections 48DJ,NP054-074 Units Gas Heat DK034,044 Units Gas Heat DK054-074 Units Typical Wiring Schematic 48/50DJ,50DW Units 054-074 Shown Typical Wiring Schematic 48/50DJ,50DW Units 054-074 Shown Typical Wiring Schematic 48/50DK,50DY Units 054-074 Shown Typical Wiring Schematic 48/50DK,50DY Units 054-074 Shown Page Page Page Page Packaged Service Training Page Model no Serial no Date Technician OUTDOOR-AIR TemperatureRETURN-AIR Temperature Supply Voltage L1-L2

NP034-074 specifications

The Carrier NP034-074 is an advanced rooftop unit designed for commercial heating, ventilation, and air conditioning (HVAC) applications. This unit is part of Carrier’s extensive range of rooftop units that are known for their energy efficiency, reliability, and innovative features. The NP034-074 series is particularly recognized for its robust performance in diverse environmental conditions, making it ideal for a variety of commercial building types.

One of the standout features of the NP034-074 is its high-efficiency compressor. Equipped with a scroll compressor, the unit offers enhanced performance and quieter operation compared to traditional reciprocating compressors. This design not only improves energy efficiency but also reduces operating costs over time. The unit is designed to meet or exceed the latest efficiency standards, ensuring that businesses can enjoy optimal indoor comfort while keeping energy consumption low.

The NP034-074 also integrates advanced control technologies that provide users with greater flexibility and ease of operation. The intuitive control system allows for precise temperature management and can be easily integrated with building automation systems. This enables users to monitor and adjust settings remotely, ensuring consistent and efficient climate control throughout the facility.

Another key characteristic of the NP034-074 is its robust construction. Built to withstand various weather conditions, the unit features a galvanized steel cabinet with a powder-coated finish for corrosion resistance. Its design also facilitates easy access for maintenance and service, which minimizes downtime and operational interruptions.

In terms of air distribution, the NP034-074 incorporates a powerful blower system that ensures even and effective airflow throughout the space. This design improves indoor air quality by enhancing ventilation while maintaining comfort levels. Additionally, the unit can be customized with options such as economizers and variable speed fans to optimize performance based on specific building needs.

The NP034-074 is a versatile and reliable choice for businesses looking to enhance their HVAC systems. With its combination of energy efficiency, advanced technology, and robust construction, this rooftop unit stands out as a top choice for commercial climate control solutions.