Carrier 48DD User's Manual
Contents
1. Gas Heating 275 000 Btuh Electric Cooling 124 000 Btuh 48DD012 DESCRIPTION The 48DD012 is a one piece combination gas heating buildings The unit is completely factory assembled electric cooling unit designed primarily for outdoor rooftop charged and tested Requires only natural gas and suitable installation on a factory supplied curb accessory but can be electrical and duct connections for hookup Air can be installed on grade or conventional steel framework This supplied to the building either thru bottom of the unit or unit combines superior performance with compactness thru the side A manually adjustable outdoor air intake is versatility of application and ease of installation to supply provided Condensers are air cooled Low silhouette design year round air conditioning for commercial and industrial allows units to be easily hidden from street level view FEATURES Two Stage Heating and Cooling Both heating and Automatic Electric Ignition Pilot flame is auto cooling stages have 50 percent or 100 percent capacity matically relighted in case of interruption of power or gas ranges of operation This reduces operating costs Aluminized Heat Exchangers Resist corrosion and provide long quiet safe and efficient operation These Multiple Choice of Air Flow Air can be delivered to heat exchangers have a full ten year warranty the building either thru the bottom of the unit with separate inlet and outlet air2. changeover is available temperature is below 60 F It can replace operation of the Remote Control Center allows manual control of the refrigerant system under these conditions unit from a location remote from the thermostat The LP Conversion Kit used to convert the unit from natural thermostat furnished with the remote control center has no gas to LP gas usage knobs or switches for manual control Relief Damper used to relieve positive building pressure O Carrier Corporation 1970 Single Feature Sheet Available Form 48DD 1P D DIMENSIONS i DIAM FiELO CONTROL POWER SUPPLY CONN H CONDOENSER SECTION ALTERNATE CONDENSER END VIEW CONN CONDENSER AIR FLOW D EVAPORATOR AIR FLOW SPACE REQUIRED FOR SERVICE CLEARANCE AND AIR FLOW Dimensions ere approximate Certified dimensions ere available on request PHYSICAL DATA o UNIT 48DD n 012 OPERATING WEIGHT I 1690 REFRIGERANT 22 Operating Charge lb 9 each System COMPRESSOR 2 Reciprocating Hermetic Cylinders Rpm 60 Hz 4each 3500 OUTDOOR AIR FANS Propeller Direct Drive No Diam in 2 22 Nom Cfm each total 3200 6400 V 1140 3 phase 1075 1 phase Motor Hp Rpm CONDENSER COIL Plate Fin Rows Fins in 4 13 Total Face Area sq ft 140 INDOOR AIR FANS 7 Centrifugal Belt Drive No Size in 2 10x 10 Nom Cfm 4000 Rpm Range Standard Drive 1230 to 1540 Max Allowable Rpm 1700 B
3. ducts or concentric ducting or Time Guard Circuit prevents rapid cycling extends it can be delivered thru the side of the unit with separate compressor life When power to unit is interrupted inlet and outlet air ducts 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 Gas Safety Control will shut off the main gas valve in case of pilot or combustion air failure or overheating of the heat exchangers i Other Quality Components Crankcase heaters and Induced Draft Combustion Unaffected by winds and accumulators to protect the compressor against flooded drafts Equipped with safety shut off devices in case of starts filter driers and sight glasses for moisture control and combustion air failure or blockage visual inspection of refrigerant charge ACCESSORIES e 32LM Motormaster Head Pressure Control mod Roof Curb frames roof opening is watertight connec ulates speed of condenser fan motor to maintain saturated tion between unit and roof Designed so ductwork and roof condensing temperature at low outdoor temperatures flashing may be installed prior to placing the unit Thermostat Assembly is a two step heating two step Modulating Outside Air Control Package economizer cooling thermostat and a matching switch base Either can furnish outside air for cooling when outside air automatic or manual
4. fired heating Total Net Cooling Capacity of the system shall be 124 000 Btuh or greater and sensible capacity shall be 94 900 Btuh or greater at conditions of 4500 cfm evaporator air entering unit at 67 F wet bulb 80 F dry bulb and condenser entering air temperature of 95 F dry bulb Compressor power input shali not exceed 15 5 kw Heating Capacity of the system shall be 206 000 Btuh or greater with gas input of 275 000 Btuh Casing shall be constructed of galvanneal steel bonderized and coated with baked enamel Compressor The unit shall contain two hermetic compressors with suitable vibration isolators Crankcase heaters shall be supplied with the unit Coils shall be constructed with aluminum plate fins mechanically bonded to copper tubes Fans and Motors The indoor fan shall be of the forward curved centrifugal type belt driven by a 3 hp motor The condenser section shall have two propeller fans each directly driven by a 1 2 hp motor Heat Exchanger shall be constructed of corrosion resistant aluminized steel Burners shall be of the Bunsen aerated slotted port type readily accessible and covered by a 10 year warranty Safety Controls Cooling section shall be protected by fusible plug low pressurestat compressor motor overloads and a timing device which wil prohibit the compressor motor from being subjected to starting current more than once every five minutes Heating Controls shall consist of an auto
5. ACLE EM CENE e Cara a Ri wawa Le _4IPLUG 1 I 1 i I I I R2 Re R RES 1 R2 MAT R2 CURR BAL RELAY T7773 E2777 cw CCW amp v C voron SHAFT LEGEND c Compressor Contactor LP Low Pressure Switch cc Cooling Compensators LS Limit Switch Cew Counterclockwise MAT Mixed Air Thermostat CH Crankcase Heater NS Night Switch CR Control Relay Field supplied cs Centrifugal Switch OAT Outside Air Thermostat Cw Clockwise OFC Outdoor Fan Contactor DM Damper Motor Ol Overload FDM Forced Draft Motor Pil Pilot FDR Forced Draft Relay R Relay GC Glow Coil RES Resistance Wire GV Gas Valve TB Terminal Block GVR Gas Valve Relay TC Thermostat Cooling HA Heating Anticipator TDR Time Delay Relay HPCT Head Pressure TH Thermostat Heating Control Thermostat TM Timer Motor HR Holding Relay TRANS Transformer IFC Indoor Fan Contactor IFR Indoor Fan Relay Factory Wiring IP nternal Protector Field Wiring ELECTRICAL DATA Cont ELECTRICAL DATA 60 Hz VOLTAGE T COMPR IFM OFM IFM Indoor Fan Motor RANGE WSA ICF FU FLA LRA FLA eo LRA Locked Rotor Amps OFM Outdoor Fan Motor WSA Wire Sizing Amps per NEC equals 1 25 x FLA of the largest motor plus the sum of the FLA of all
6. LS Protective Devices Limit Switches shut off gas supply if excessive air temperatures should develop limit discharge air temperature to 175 F when unit is used for heating Current Overloads with Automatic Reset are current sensitive and temperature compensated will open the control circuit if compressor current is excessive e Internal Thermostat with Automatic Reset is embedded in compressor windings de energizes the control circuit if extreme temperatures should develop due to excessive suction gas tempera ture or motor overloading High Pressure Relief Device protects unit from excessive com pressor discharge pressures and prevents overheating Circuit Breaker provides short circuit protection for controls Low Pressurestat with Automatic Reset de energizes the control circuit if refrigerant pressure drops below setting provides pro tection from loss of refrigerant charge e Inherent Fan Motor Protection with Automatic Reset opens power circuit if temperatures or current become excessive on 3 phase motors single phase motors are temperature sensitive only Fusible Plug located on the accumulator protects against excessive pressures or temperatures in the refrigerant system e Centrifugal Switch located in the induced air fan motor will de energize the gas valve in case of combustion air failure GUIDE SPECIFICATIONS Unit shall be of the single package type combination air to air cooling and gas
7. elt Type Length in A 44 Motor No Hp Rpm 3 1745 Max Brake Hp 3 45 Frame 182T Shaft Diam in 1 Pulley Pitch Diam in 7 356 V 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 i 2x93 SELECTION PROCEDURE With Example Determine cooling and heating requirements at design conditions GIVEN Required Cooling Capacity TC Sensible Heat Capacity SHC Required Heating Capacity 128 000 Btuh 90 000 Btuh 198 000 Btuh Condenser Entering Air Temp 95F Indoor Air Temp 80 F Edb 67 Ewb Evaporator Air Quantity z 4000 Cfm Electrical Characteristics 230 3 60 External Static Pressure 8 in wg Select unit based on required cooling capacity Enter Cooling Capacities table at condenser entering air tempera ture 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 of 96 000 Btuh Calculate SHC correction if required Compare the heating capacity of the unit selected with the design conditions Unit 48DD012 provides an input of 275 000 Btuh with a bonnet capacity of 206 000 Btuh IV Determine fan speed and brake hp requirements at design conditions Enter Fan Performance table At 4000 cfm and 8 in wg the fan speed is 1405 rpm and brake hp is 2 34 The table indicates that standard drive is adequate V Select unit that co
8. fied outdoor and indoor fan motors and the compressor shut off and the outside air damper closes Damper always stays at Vent during cooling sequence if fan switch is at Fan and night switch is closed Intermediate Season Same as for cooling season except that as step 1 of thermostat closes and indoor fan motor starts compressor and outdoor fan motor remain off if outside air temperature is below outdoor air thermostat setting If outside and return air temperature rises above or drops below mixed air thermostat setting the outside a r damper will reposition to maintain the thermostat setting Damper will move to closed position when cooling step 1 is satisified Damper will move to Vent position when fan switch is at Fan The outside air damper will close when the night switch is opened night position or whenever the indoor fan shuts down Heating Season Damper always stays at Vent while fan motor is operating Outside air damper closes when night switch opens TYPICAL WIRING Ll TRANS L2 IIS V FDR g IFRI e amp IFR2 Gc CRI e ra HRI LP O Ol2 o3 IPI AR i i HRI Kk CHI XAT RECEPTACLE HR TB9 CRI CR2 LP2 TO ECONOMIZER R L 34 oO Q Q Q A OL4 OL5 OL6 IP HR2 CH2 TRANS TDR 24V e CRi GVR LSi PILI PIL2 CS GVR GV xO O O TG OTO OO o o TH i E LSe LS3 LSa GC GC RES i TH m RMOSTAT TO RECEPT
9. l across the standard motor i heat exchanger and clean filters 3 All table values printed in italics indicate non standard conditions ELECTRICAL DATA OPERATING SEQUENCE Cooling Power on and thermostat assembly set at Cool Fan Auto and desired temperature Step 1 of cooling thermostat energizes outdoor and indoor fans and Time Guard Circuit Time Guard Circuit delays the start of the compressor for fifteen seconds Step 2 of cooling thermostat operates a second Time Guard Circuit which delays the start of the second compressor for fifteen seconds On compressor shutdown for any reason Time Guard Circuit prevents compressor restart for at least five minutes Capacity Control i wo step thermostat operates the compressors as the cooling load changes Heating Turn power and gas on and set thermostat assembly at Heat Fan Auto and desired temperature The induced draft motor is energized whenever unit field power is on with thermostat set for Heat or Auto No 1 glow coil ignites the no 1 pilot a thirty second delay occurs before glow coil lights the pilot Electric pilot shifts to no 2 glow coil and no 2 pilot ignites After al pilots ignite unit is ready to heat When step 1 of heating thermostat closes the gas valve relay energizes the main gas valve opens the indoor fan relay IFR 2 closes the indoor fan contactor energizes and the indoor fan motor starts Burners are now at 50 perce
10. matic gas valve pilot automatic ignition system limit switches and a centrifugal switch Dimensions The unit casing shall have width of not more than 65 in length of not more than 87 in and height of not more than 42 inches Accessories Roof Curb Modulating Outdoor Air Control Remote Control Center Two Stage Heat Coo Automatic Change over Thermostat Relief Damper LP Conversion Kit and 32LM Motormaster Head Pressure Control Manufacturer reserves the right to change any product specifications without notice CARRIER AIR CONDITIONING COMPANY e Tab 6 Form 48DD 1P New Printed in U S A SYRACUSE NEW YORK 2 70 Codes B and MS Catalog No 524 811
11. nt capacity When step 2 of heating thermostat closes and energizes the second stage of gas valve the unit operates at fuH capacity When call for heat is satisfied step 2 of thermostat opens de energizing the second stage of the gas valve Unit may cycle between 50 percent and full capacity as step 2 dictates When step 1 of the thermostat opens the gas valve relay shuts off the main gas valve and indoor fan motor Automatic Changeover When system selector switch is set at Auto unit will automatically change from heating to cooling when the temperature of the conditioned space rises to the cooling lever setting When the temperature of the conditioned space falls to the heating lever setting the unit will automatically change from cooling to heating The thermostat and unit are so connected that the cooling and heating systems will not operate simultaneously Air Circulation With power on and unit controls set at Off and Fan indoor air fan operates continuously for air circulation When controls are set at Heat or Cool and Fan heating or cooling is provided as required while indoor fan motor operates continuously OPERATING SEQUENCE ACCESSORY MODULATING OUTSIDE AIR CONTROL Cooling Season Thermostat assembly set at Cool and Fan Auto Damper goes to Vent when step 1 of cooling thermostat closes energizing outdoor and indoor fan motors and the compressors When step 1 is satis
12. other motors in 220 180 179 6 152 100 27 60 110 10 6 3 2 230 3 254 198 170 0 460 3 506 414 339 69 45 11 85 the unit CER ae cee DS Unit has two compressor motors values are for each FU Fuse max allowable amps ICF Max Instantaneous Current Flow during start up is the sum of compressor LRA plus the FLA of all other motors in the unit TYPICAL PIPING AND WIRING ROOFTOP INSTALLATION WITH SEPARATE SUPPLY AND RETURN DUCTWORK CONTROL WIRING POWER WIRING ROOF CURB Pare m e dram Vm Metern ARRAES m aA See She EZ o Oe ac um TA E NOTE Accessory economizer cannot be used with this air flow arrangement APPLICATION Cont LOW OUTDOOR TEMPERATURE COOLING OPERATION It is not necessary to use the refrigeration system for cooling when the outdoor air temperature is below 60 F The use of outdoor air will handle the cooling load This is a more economical method of cooling in cold weather One condenser fan motor is cycled off when the outdoor air temp drops to 55 F This allows operation down to 35 F outdoor temperature The other condenser fan motor is suitable for use with the 32LM Motormaster TM Head Pressure Control at outdoor temperatures below 35 F see Accessories Operation with this control requires winter start provisions low pressure switch recalibration and may require field fabricated condenser air baffles CONTRO
13. rresponds to available power source Refer to Electrical Data table and choose unit as required A 48DD012 230 3 60 is available PERFORMANCE DATA COOLING CAPACITIES 60 Hz 48DD012 ARI 124 000 BTUH CORNER UNA E NOTES Evap Ae Cfm BF poem 30004 08 TY rm PA ERUAT 12 1 Direct FOI DOTBEION is permissible Do not extrapolate ETE TEv g Aire Ewbs F 2 The following formulas may be used 144 11310 Idb tedb 1 08 x cfm 140 13 al Wo d tiwb Wet bulb temperature corresponding to enthalpy of air pre AE re a Pe 1 il CE mn ANA 6 108 6 eaving PVSROCGIO coil hiup A 84 911091 4 3 128 6 h J total capacity Btuh 19 6 14 9 ie 15 6 15 0 Weer LEWD 4 5 x cfm 1340124 8111481137 6 j 125 3 8401996 737 125 1 Where 14 6 15 4 hewb Enthalpy of air entering evaporator coil D 3 SHC is based on 80 F edb temp of air entering evaporator coil 159 Below 80 F edb subtract corr factor x cfm from SHC 170 14 0 10151140 ete ANE l6 8 Entering Air Dry Bulb Temp F 79 78 77 76 75 vwnde75 Rated in accordance with latest ARI Standard 210 BF zy Capacities shown except ARI are gross capacities ES which do not include a deduction for indoor fan ON n Correction Factor e motor heat 10 97 195 292 3 89 4 86 ex eros BF Bypass Factor 20 86 73 2 99 3 46 4 32 shown below Ewb Entering Wet Bulb 30 76 151 2 27 3 03 3 78 KW Compre
14. ssor Motor Power Input ITE 7 LUC RE Tae SHC Sensible Heat Capacity 1000 Btuh Interpolation is permissible TC Total Capacity 1000 Btuh Correction Factor 1 08 x 1 BF x edb 80 HEATING CAPACITIES IN PUT BONNET 3 At altitudes above 2 000 ft the following formula may be used UNIT 48DD012 BE vcn j _ Btuh Btuh Kee bonnet capacity First Stage 137 000 103 000 000 24 x specific weight of air x 60 air quantity nace ares rat sciatica bes isis NS 4 Maximum allowable gas pressure is 140 in wg Minimum allowable gas pressure for full rated input is 5 O in wg NOTES 5 Unit may be field converted for 100 percent LP gas using Carrier factory parts Units will maintain A G A certification if conversion is performed as directed and conversion nameplate is attached to unit adjacent to existing unit nameplate 1 Ratings are approved for altitudes to 2 000 ft At altitudes over 2 000 ft ratings are 4 percent less for each 1 000 ft above sea level 2 At altitudes up to 2 000 ft the following formula may be used to calculate air temp rise bonnet capacit At bonnet capacity 1 08 x air quantity FAN PER FORMANCE 48DD012 p ras dr 7 aie 8 ES 9 10 se 11 Tu 13 3 s E OM Fan Rpm 1205 1270 1330 i 1075 i 1135 1 L195 Motor brake horsepower NOTES 2 Fan motor bhp is based on minimum voltage and 80F air 1 Fan performance has deductions for unit casing losses wet coi
Download Pdf Manuals
Related Search