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Resumen del manual
This unit combines superior performance with compactness, versatility of application and ease of installation to supply year-round air conditioning for commercial and industrial buildings The unit is completely factory assembled, charged and tested Requires only natural gas, and suitable electrical and duct connections for hookup. Air can be supplied to the building either thru bottom of the unit or thru the side A manually-adjustable outdoor air intake is provided Condensers are air cooled Low silhouette design allows units to be easily hidden from street level view FEATURES • Two-Stage Heating and Cooling — Both heating and cooling stages have 50 percent or 100 percent capacity ranges of operation This reduces operating costs • Multiple Choice of Air Flow — Air can be delivered to the building either thru the bottom of the unit with separate inlet and outlet air ducts or concentric ducting, or it can be delivered thru the side of the unit with separate inlet and outlet air ducts • Gas Safety Control will shut off the main gas valve in case of pilot or combustion air failure, or overheating of the heat exchangers • Induced Draft Combustion — Unaffected by winds and drafts Equipped with safety shut-off devices in case of combustion air failure or blockage • Automatic Electric Ignition — Pilot flame is automatically relighted in case of interruption of power or gas • Aluminized Heat Exchangers — Resist corrosion and provide long, quiet, safe, and efficient operation These heat exchangers have a full ten-year warranty • Time Guard Circuit* prevents rapid cycling, extends compressor life When power to unit is interrupted, compressor cannot restart for five minutes • Head Pressure Control automatically cycles one of two condenser fans, permitting cooling operation down to 35 F ambient temperature • Other Quality Components — Crankcase heaters and accumulators to protect the compressor against flooded starts, filter-driers and sight glasses for moisture control and visual inspection of refrigerant charge ACCESSORIES • 32LM Motormaster™ Head Pressure Control modulates speed of condenser fan motor to maintain saturated condensing temperature at low outdoor temperatures • Thermostat Assembly is a two-step heating/two-step cooling thermostat and a matching switch base Either automatic or manual changeover is available • Remote Control Center allows manual control of the unit from a location remote from the thermostat The thermostat furnished with the remote control center has no knobs or switches for manual control • Roof Curb frames roof opening, is watertight connection between unit and roof Designed so ductwork and roof flashing may be installed prior to placing the unit • Modulating Outside Air Control Package (economizer) can furnish outside air for cooling when outside air temperature is below 60 F. It can replace operation of the refrigerant system under these conditions • LP Conversion Kit used to convert the unit from natural gas to LP gas usage • Relief Damper used to relieve positive building pressure © Carrier Corporation 1970 •Single Feature Sheet Available Form 48DD-1 P DIMENSIONS ! diam fíelo contro: POWER SUPPLY CONN I IPS GAS PIPE IPS DRAIN CONN 2 DIAM FIELO POWER SUPPLY CONN. 'CONDENSER AIR FLOW • EVAPORATOR AIR FLOW ШЯ SPACE REQUIRED FOR SERVICE CLEARANCE AND AIR FLOW ROOF OPENINGS Dimensions are approximate. Certified dimensions are available cn request. PHYSICAL DATA UNIT 48DD 012 OPERATING WEIGHT (ib) 1690 REFRIGERANT 22 Operating Charge (Ib) 9 each System COMPRESSOR (2) Reciprocating Hermetic Cylinders...Rpm (60-Hz) 4 each 3500 OUTDOOR AIR FANS Propeller; Direct Drive No. ...Diam (in.) 2 22 Nom Cfm each...total 3200 .6400 % 1 140 (3-phase) Motor Hp...Rpm 1 075 (1 -phase) CONDENSER COIL Plate Fin Rows... Fins/in. 4 13 Total Face Area (sq ft) 14 0 INDOOR AIR FANS " Centrifugal; Belt Drive No. ...Size (in.) 2 10x10 Nom Cfm 4000 Rpm Range (Standard Drive) 1230 to 1540 Max Allowable Rpm 1700 Belt Type...Length (in.) A. 44 Motor No. ...Hp...Rpm 1 3 1745 Max Brake Hp 3 45 Frame 182T Shaft Diam (in.) 1V8 Pulley Pitch Diam (in.) 5 6 EVAPORATOR COIL Plate Fin Total Face Area (sq ft) 10 02 Rows... Fins/in. 3 14 HEAT EXCHANGERS Aluminized Steel A.G.A. Certified Rise 45 to 75 F No. ...Elements (each) 2 .5 SELECTION PROCEDURE (With Example) I Determine cooling and heating requirements at design conditions. GIVEN: Required Cooling Capacity (TC) Sensible Heat Capacity (SHC) Required Heating Capacity Condenser Entering Air Temp Indoor Air Temp Evaporator Air Quantity Electrical Characteristics External Static Pressure 128.000 Btuh 90,000 Btuh 198.000 Btuh . 95 F 80 F Edb, 67 Ewb 4000 Cfm 230-3-60 8 in. wg II Select unit based on required cooling capacity. Enter Cooling Capacities table at condenser entering air temperature of 95 F. The 48DD012 at 4000 cfm and 67 F Ewb will provide a total capacity of 132,000 Btuh and a sensible heat ...