Bryant 379A User's Manual
Contents
1. air openings The ductwork may be screwed or bolted to the unit flange with suitable gaskets to insure weathertight seal Be sure that the sheet metal overlaps the flange on the unit All ductwork external of the structure must be properly insulated and waterproofed All openings in the structure must be properly flashed and vibration isolated in accordance with local codes and good building practices The supply and return ductwork should be provided with an approved vibration eliminator NOTE The vibration eliminator must be located within the structure NOTE An external filter must be PEE wd in stalled where easily accessible for servi e For the minimum filter area see the unit rating plate i V VENTING A vent cap assembly and a rahest Taa anple air deflector are packaged and shipped with the unit The package is located in the blower compartment ROOF LINE DRIP LEG DO NOT DROP TO SLAB GRADE LEVEL _ A70676 Figure 3 Drip Leg Location oe 39379D36 PROPANE UNITS ONLY MOUNT AIR aif weeweiiit III hy LEFT SIDE HEATING SECTION Figure 4 Mounting Air An air shroud is also shipped with propane units only Install these items as follows 1 Remove the cover from the vent opening on the unit 2 Remove the top plate from the vent cap eee held by 4 sheet metal screws 3 Use the screws supplied with the assembly to fa2. 144 cubic feet per hour of gas flow d 144x1050 151 200 Btuh input Only minor changes should have to be made at the pressure regulator to bring it within the rated input of the unit B Using Water Manometer When using a water manometer to measure the gas manifold pressure proceed as follows to adjust the gas input 1 Turn off gas to unit 2 Remove the 1 8 inch pipe plug on the furnace manifold and connect manometer here See Figure 6 3 Turn on gas to unit With the burners fired adjust the pressure regulator to obtain the correct manifold pressure as shown in Table IV Check with local gas utility for Btu value and specific gravity of gas in the area 39379D36 PILOT GAS PRESSURE SWITCH PILOT GAS COCK COMBINATION REGULATOR SHUTOFF VALVE GAS VALVE pitoT BURNERS 5 PIPE PLUG A721454 Figure 6 Front View of Partially Disassembied 48W 379A 4 Remove manometer from manifold and replace the _1 8 inch pipe plug removed in Step 2 above Example Heating value of gas is 1050 Btu and specific gravity of gas is 0 63 a From Table IV the manifold pressure required for 150 000 Btuh input is 2 8 inches water column b Set manifold pressure to 2 8 inches w c by ad justing gas pressure regulator adjusting screw If required manifold pressure exceeds 3 3 inches w c or is less than 2 7 inches w c the burner orifices should be sized according to nit requirements Con s
3. 5 Refer to the dimensional drawing on page 2 for location of electrical gas and chilled water con nections prior to setting the unit in place GENERAL The design of this unit is certified by A G A for use with natural or propane gases with appropriate con trols and orifices This unit is designed for outdoor in stallation only Installation of the unit consists of the following I Locating the Unit II Gas Piping TII Duct Connections IV Venting V Coil Connections VI Electrical Connections VII Start up and Adjustments 39379D36 4 15 72 A72152 Figure 1 Model 48W 379A In addition the following section should be reviewed by the equipment owner VIII Maintenance LOCATING THE UNIT Extreme caution should be used when rigging and moving the unit to prevent damage The unit should be kept upright during all rigging and moving operations To facilitate lifting and moving place the unit i in an n an made us Tope or cable Rooftop Installation Level the unit on a base that is at least 6 inches above the roof to provide drainage from beneath the unit Consult local codes for installation requirements Be sure that the roof will support the additional weight Ground Level Installation If the unit is to be installed on the ground it should be placed on a level concrete slab with a minimum thickness of 4 inches 48W amp 60W 379A 1 EPT WATER CONNECTIONS Teas CON
4. Btuh The burners are equipped with fixed orifices The burners on natural gas units use No 41 drill size orifices while the burners on the propane units are equipped with No 54 drill size orifices The natural gas unit is equipped with an A639 gas valve and a combination regulator shutoff valve The propane gas unit uses an A639 gas valve but is not equipped with a regulator The regulator for propane units 1 is alocarea at the suppy tank One of the two following methods may be used to ad just the gas input on a natural gas unit A Measuring Gas Flow at Meter All other gas appliances must be turned off when measuring the gas flow at meter to adjust the gas in put Proceed as follows when using this method 1 Determine the number of seconds required for the gas meter test dial to complete one revolution 2 Divide 3600 by the number of seconds in Step 1 3 Multiply the result in Step 2 by the nue of cubic feet of gas flow per hour 4 Multiply the result of Step 3 by the Btu heating value of the gas consult local utility for value This is the total measured Btu hr input Compare this value with the one shown on the rating plate Example Suppose the size of the test dial is 2 cubic feet it takes 50 seconds for the dial to complete one revolution heating value of the gas is 1050 Btu per cubic foot Proceed as follows a 50 seconds to complete one revolution b 3600 divided by 50 equals 72 c 72x2
5. NECTION LEFT SIDE FRONT RIGHT SIDE REAR A69163 Figure 2 Dimensional Drawing TABLE HEATING CAPACITY __ 2 ee Heating Input Bth 150 000 Heating Output Buth TABLE Il RATINGS AND PERFORMANCE Model swe 79A_ GOW 379A Water Pressure Drop Ft 181 os oO TI Ratings given in Table II are for Model 48W 379A connected to a Model 48 453 Chiller and Model 60W 379A connected to a Model 60 452 Chiller TABLE ill ELECTRICAL CONNECTIONS C E War e If other than 75 C copper is used determine size from unit ampacity and the National Electric Code Voltage drop of wire selected must be less than 2 of unit rated voltage Connections of aluminum wire must be in accordance with the National Electric Code 39379D36 a ae ESA NOTE It is important that the unit be installed in a level position Clearances The minimum clearance is 6 inches from the duct side 24 inches on all other sides and 0 inches on the bottom This permits the use of combustible materials N for supports CAUTION When using rails etc as support make Bei eee li GAS PIPING allowances for surface water drainage under the 1 unit 2 A separate gas supply line should be meled to run directly from the meter to the furnace Check your local utility for recommendations concerning existing lines Choose a supply pipe sized la
6. WER RELAY COOLING HI TEMP ER LIMIT CONNECTIONS CHILLED Ei WATER BLOWER COIL SHIPPING BOLT OILING AND BRACKET CABEL CONDENSATE DRAIN CONNECTION A72153 Figure 5 Rear View of Partially Disassembled 48W 379A Refer to the chiller installation instructions for per tinent information concerning type and size of piping length of pipe permissible type of freeze protection and chilled water additive required VI ELECTRICAL CONNECTIONS All deem et ee are to be made in ac cordance with the National Electrical Code and the ses lt E local code governing such wiring Field low voltage connections are to be made in accordance with the wiring diagram shown in Figure 8 A separate electrical line should be run for this in stallation and should contain a fused switch in a con venient location Refer to Electrical Connections Table III on page 2 for maximum fuse size and minimum wire size Field wiring c nnections are made in the control box located in the blower com partment See Figure 5 NOTE If aluminum conductors are used the con nections must be made in accordance with the National Electric Code Aluminum wire connections must be made with special connectors In preparing the wire just before installing the connector all aluminum wire must be brush scratched and the wire coated with a corrosion inhibitor such as Pen trox A When it is suspected that the connec
7. e has been operating for at least five minutes As soon as the limit has functioned to shutoff the gas valve unblock the return air opening to permit nor mal air circulation Blower Fan Relay Heating The heating blower fan relay 2G is located in the control box and is adjustable to permit lengthening or shorting the OFF cycle The ON cycle is automatically adjusted as the OFF cycle is changed The fan control adjusting lever is factory set at the center position and should give optimum performance in most installations However on unusual in stallations or where the line voltage is considerably above or below the rated output it may be necessary to increase or decrease the length of time the blower remains on For longer blower operation move the adjusting lever toward the MAX OFF position In this position the control line switch makes contact sooner and takes the maximum time to break contact For shorter blower operation move the lever in the opposite direction Blower Fan Relay Cooling The unit is also equipped with a cooling blower fan relay 2A When a chiller is used in conjunction with the furnace to form a combination heating and cooling system this relay is energized by the chiller transformer when there is a demand for cooling 39379D36 Adjusting Gas Input The gas input must be checked and adjusted if necessary to agree with that shown on the unit rating plate 150 000
8. i installation Instructions 379A Models Series C OUTDOOR HEATING UNIT Bryant Models 48W 379A and 60W 379A are outdoor heating units designed for installation on a rooftop or at ground level Both models have a chilled water coil factory installed Model 48W 379A is equipped witha 48 000 Btuh coil while Model 60W 379A is equipped with a 60 000 Btuh coil These units were designed for use in split systems with matching Bryant gas fired water chillers Both models have 150 000 Btuh heating input rating and a 112 500 Btuh heating output rating Model 48W 379A has a 48 000 Btuh cooling rating when connected to a Bryant Model 48 453 Gas Fired Water Chiller Model 60W 379A has 60 000 Btuh cooling rating when con nected to a matching Bryant Model 60 452 Gas Fired Water Chiller Important Read before Installing 1 Check all local or other applicable codes for in formation concerning proximity to property lines height above roof obstructions etc 2 Be sure the power supply available voltage frequency and phase corresponds to that specified on the unit rating plate 3 Check the electrical service provided by the utility for the building to be sure that the service capacity is sufficient to handle the load imposed by this unit 4 Refer to the regulations of the serving gas supplier and the local building heating plumbing or other codes in effect in the area in which installation is to be made
9. move and inspect air filters for clogging due to dirt When necessary replace disposable filters or clean permanent type filters using clear water Be sure to coat permanent filters with a water soluble oil after cleaning if instructions require it LEGEND 1B Transformer 2A Blower Fan Relay Cooling 2G Blower Fan Relay Heating 3A Blower Motor 5B Magnetic Gas Valve 6B Reignition Pilot 7K Hi Temp Limit 7P Pilot Pressure Switch 11A Resistor A72155 Figure 7 Modeis 48W and 60W 379A Wiring Diagram y 39379D36 39379D36 THERMOSTAT AND SUB BASE BRYANT P N 34427D031 SYSTEM HEAT OFF COOL AUTO ON FLAGGED WIRES MODEL 48W 379A MODEL 48 453 a OR 6OW 379A OR 60 452 _ A o oi CONTROL BOX CONTROL BOX ee A72163 Figure 8 Connecting Model 48W 379A to Model 48 453 Chiller or Connecting Model 60W 379A to Model 60 452 Chiller
10. pilot assembly s normally closed contacts to open and the normally open con ae ee tacts to close This action breaks the ignition circuit and makes the control circuit to the gas valve When the thermostat calls for heating terminal 4 is connected to terminal W through the thermostat This completes the circuit to the gas valve 5B and to the heating blower relay 2G The energized gas valve opens and supplies gas to the burners The contacts of the energized heating blower relay close and make the line voltage circuit to the blower motor 3A and starts the blower fan Pilot Safety Test If i pilot should go out the pilot assembly s nor mally open contacts which were closed by pilot ignition will reopen and break the circuit to the gas valve The de energized gas valve will close and shutoff the gas supply to the burners This safety feature can be checked by closing the pilot gas cock The burners should shutoff within 90 seconds NOTE The pilot will reignite automatically by means of glow coil ignition when the pilot gas cock is opened again There will be a short time delay before pilot reignition occurs Limit Control The function of the hi temp limit control 7K is to shutoff the gas supply to the burners and maintain an electrical circuit to the blower motor if the furnace becomes overheated The limit control can be checked by gradually blocking off the return air after the fur nac
11. rge enough to keep the pressure loss as low as practical AMAM ARPA pipe installations The following are pertinent recommendations 1 Avoid low spots in long runs of pipe It is best to grade all pipe 1 4 inch in every 15 feet to prevent traps All horizontal runs should grade downward to risers Risers should be used to connect to the furnace and to the meter 2 Install a drip leg in the riser oi i ie furnace This drip leg will serve as a trap for dirt and con densate Drip legs should be installed where con densate will not freeze See aas 3 for drip leg location 3 A manual shutoff valve should be installed in the gas supply pipe near the furnace where it can be easily reached 4 Place a ground joint union close to the unit e tween the gas controls manifold and the manual shutoff valve DO NOT DROP TO ROOF DRIP LEG BLG DRIP LEG WITHIN STRUCTURE 5 Support all piping with appropriate hangers etc The maximum distance between hangers should be 10 _ feet 6 Joint compound pipe dope must be resistant to _ the action of propane gas A RNING G Never tse a mat heck for gas leakag ee er 7 After all connections are 1 aie ae se SEE by using soap and water solution or in accordance with local utility regulations Il DUCT CONNECTIONS Before ductwork can be attached to the unit remove and discard the cover panel that is located over the outlet and return
12. sten the base section of the vent cap assembly to the top cover of the unit the unit top is predrilled to receive the screws 4 Reattach top plate removed in step 2 5 Remove the 3 self tapping screws located ap proximately 7 inches behind the vent cap Use these screws to attach the sheet metal angle to the unit top cover at this location 6 Use the screws enclosed in the air shroud package to mount the air shroud as shown in Figure 4 propane units only COIL CONNECTIONS S cee 5 is a rear view photo of a partially disassem bled Model 48W 379A unit The coil location and chilled water connections for both the 48W and 60W 379A are the same for both units These two models differ only in the size of the factory installed chilled water coil Two 2 3 8 inch diameter holes are provided in the right rear corner panel for the chilled water piping en trance to the unit NOTE Two packaged vinyl grommets are shipped loose in the blower compartment Insert one grommet in each of the 2 3 8 inch corner panel holes Route the chilled water piping through the two grom mets and connect to the two 1 inch F P T connectors on the coil header Refer to Figure 5 for chilled water inlet and outlet connections 39379D36 MOUNTING SCREWS ALRI LEFT SIDE p A71718 Shroud on Propane Unit BELT TENSION ADJUSTING SCREW BLOWER MOTOR CHILLED WATER CONNECTIONS TRANSFORMER BLOWER RELAY HEATING BLO
13. table flange on the blower motor pulley is cused to adjust the blower speed Proceed as described below to adjust oe motor se aes n RA m gt Figure 5 OA tie belt tensioning ide justing screw until there is slack in belt Remove belt from pulleys 2 Loosen setscrew in movable flange of blower motor pulley Screw movable flange toward fixed flange to increase blower speed and away from fixed flange to TERMINAL No TERMINAL No oe ee FACTORY LINE VOLTAGE FACTORY LOW VOLTAGE G E RELAY RBM RELAY reduce blower speed Tighten set screw on one of the two aat oe on the a y ae peste load on the o mowr Do not exceed the rated current draw of the motor 3 Replace belt and adjust for proper tenion The belt should have approximately a 3 4 inch sag under nor mal finger pressure midway between pulleys 4 Check motor pulley and blower pulley for proper alignment VIII MAINTENANCE Blower Motor Lubrication _ Lubricate the blower motor per oiling label located in blower compartment See Figure 5 Cleaning the Heating Section 1 Turn on Dova i main Oer oe Rae one access oo Turn off manual gas valve and pilot gas cock Disconnect pilot and escapement tubing Remove burners Remove flue baffle retainer and vent section shelf Remove flue baffle Clean passages with suitable brush Reassemble furnace by reversing above procedure Filters Every two months throughout the heating season re
14. tion will be exposed to moisture it is very important to cover the entire connection completely to prevent an electro chemical action that will cause the connection to fail very quickly Reducing the effective size of the wire such as cutting off strands so that the wire will fit a connector is very poor practice Proper size con nectors should be used Wiring entrances are provided in the left side of the unit Wiring entrances to the unit are shown in the dimensional drawing on page 2 NOTE The wiring entrances to the unit must be weathertight Use thermostat and subbase assembly P N 34427D031 Set thermostat heat a eee at 0 8 amps Vil STARTUP AND ADJUSTMENTS Before starting the unit make sure the gas pipe is purged and free from air Do not purge into the com DueHOn enamoer ex gag piping PROUA be jeak tentea Refer to chiller installation instructions for a circuit description of the cooling section The sequence of control operation for the furnace is as follows 1 Turn on electrical power and gas supply to unit 2 Refer to Figure 7 Note that the 24V control circuit voltage is applied across unit terminals 4 and X when power is turned on to the furnace When the pilot gas cock is opened the pilot pressure switch closes and completes the circuit to the glow coil of pilot assembly 6B which ignites the pilot Ap proximately one minute after the pilot is ignited heat from the pilot causes the
15. ult your ee Distributor TABLE IV MANIFOLD PRESSURES inches w c Adjusting Pressure Regulator If measured and rated input are not approximately the same the gas pressure regulator may be adjusted as follows To increase input Remove regulator sealing cap and turn gas pressure regulator adjusting screw clockwise To decrease input Remove regulator sealing cap oE and turn gas pressure adjusting screw counter clockwise Checking Propane Gas input The burner orifices are sized for rated input with a manifold pressure of 11 0 w c for propane gas Con nect a manometer to the 1 8 pressure tap on the gas manifold With the burners fired adjust regulator at the supply tank to provide a pressure of 11 0 w c Air Shutter Adjustment To adjust the primary air to each burner partially close the air shutter until there is a slight yellow tip on the top of the flame then open the air shutter until the yellow tip just disappears This should be done af ter the burners have been operating at full input for 5 or 10 minutes approximately Airflow and Temperature Rise The furnace is designed for operation within a tem perature rise of 45 F to 75 F all against an external static pressure up to 0 5 inch water column The external static pressure against which the blower is operating is the difference in pressures in the return air duct and discharge air duct near the furnace An adjus
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