Audelª HVAC Fundamentals Volume 2
Contents
1. 40 40 42 43 43 48 vi Contents Chapter 2 Chapter 3 Gas Burners Operating Principles Electrical Circuits Automatic Controls Types of Gas Burners Integral Type Gas Burners Gas Conversion Burners Gas Conversion Burner Combustion Chambers Gas Piping for Conversion Burners Venting and Ventilation Safety Precautions Troubleshooting Gas Burners Coal Firing Methods Coal Firing Draft Requirements Firing Anthracite Coal Firing Bituminous Coal Firing Semibituminous Coal Stoker Firing Stoker Construction Stoker Automatic Controls Stoker Operating Instructions Coal Selection Starting the Fire Natural Stack Draft Manual Air Adjustment Automatic Air Control Changing Coal Feeds Motor Overload Protection Transmission Overload Protection Removal of Obstruction Lubrication Summer Service How to Remove Clinkers How to Adjust Coal Feed Contents vii How to Adjust Air Supply 94 Troubleshooting Coal Stokers 94 Chapter 4 Thermostats and Humidistats 99 Automatic Control Systems 99 Temperature Control Circuits 100 Thermostats 100 Thermostat Components 105 Thermostat Terminal Identification 109 Thermostat Anticipators 109 Types of Thermostats 119 Room Thermostats 119 Programmable Thermostats 125 Insertion Thermostats 125 Immersion Thermostats 126 Cylinder Thermostats 127 Boiler Thermostats 129 Remote Bulb Thermostats 129 Proportional Thermostats 132 Outdoor Thermostats 132 Troubleshooting Th2. A C COMPONENT OF CENTRIFUGAL FORCE if PROJECTING OIL DROPS ea a TOWARD RIM OF CUP OIL FEED TIP Figure I 18 Detail of cup showing centrifugal forces acting on the droplets of oil which flatten them into a film and project them toward and off of rim same burner This is particularly advantageous in areas where low cost gas is sometimes available The combination gas and oil burner illustrated in Figure 1 21 contains independent ignition and control systems for gas or oil One convenience built into these combination burners is that the oil burner components and parts are standard and require only conventional service procedures The safety features include a standard cadmium sulfide detection cell and primary relay con trol Fuel Pump A wide variety of different makes and models of fuel pumps are available for use with oil burners Both single stage and two stage 20 Chapter POT OR VAPORIZER ae ASSEMBLY FLAME 3 AIR DUCT FAN HOUSING SPREADER f ELECTRIC MOTOR OIL CONTROL VALVE ELECTRIC JUNCTION BOX ADJUSTABLE LEGS Figure I 19 Vaporizing pot type oil burner illustrating the connection to the pot or vaporizing assembly Figure I 20 Vaporizing pot type oil burner with cutaway of pot or vaporizing assembly Courtesy U S Department of Agriculture OIL LEVEL CONTROL VALVE Oil Burners 21 Figure l 21 Combination oil and gas burner Courtesy Wayne Home Equipment Co Inc f
3. and the pressure relief valve closes 14 Chapter ADJUSTING SCREW CLOSING SPRING STRAINER a CUTOFF VALVEN BELLOWS NOZZLE f SPRAY ADJUSTING SCREW RETURN TO INLET LINE ONE PIPE PRESSURE RELIEF VALVE RETURN TO TANK TWO EIDE CLOSING SPRING Figure l 14 Schematic sectional view of separate unit cutoff valve and pressure relief valve showing strainer pump and piping However oil will continue to discharge from the nozzle until the pressure drops below the cutoff valve setting when the cutoff valve closes and stops the nozzle discharge A passage to the return line is provided by a small slot cut in the seat of the mushroom valve This causes any remaining pressure trapped in the line by the closing of the cutoff valve to be equalized Frequently the cutoff valve and pressure relief valve are com bined in a compact cylindrical casing see Figure 1 15 Here the two valves are attached to a common stem with a flange which comes in contact with a stop when moved upward by the pressure of the valve actuating the spring The position of the stop limits the valve movements to proper maximun lift A piston free to move in the cylindrical casing has an opening in its head that forms the valve seat for the pressure relief Oil Burners 15 i screw OSS YASS ADJUSTING Y NN N STRAINER N 2 N aN N N N INLET N N N NI a i N N PISTON SARDA ESS dig N wae N
4. type of work but also for the homeowner interested in maintaining an efficient and trouble free HVAC system A special effort was made to remain consistent with the terminology definitions and practices of the various professional and trade associations involved in the heating ventilating and air conditioning fields Volume 1 begins with a description of the principles of thermal dynamics and ventilation and proceeds from there to a general description of the various heating systems used in residences and light commercial structures Volume 2 contains descriptions of the working principles of various types of equipment and other compo nents used in these systems Following a similar format Volume 3 includes detailed instructions for installing servicing and repairing these different types of equipment and components The author wishes to acknowledge the cooperation of the many organizations and manufacturers for their assistance in supplying valuable data in the preparation of this series Every effort was made to give appropriate credit and courtesy lines for materials and illustrations used in each volume Special thanks is due to Greg Gyorda and Paul Blanchard Watts Industries Inc Christi Drum Lennox Industries Inc Dave Cheswald and Keith Nelson Yukon Eagle Bob Rathke ITT Bell amp Gossett John Spuller ITT Hoffman Specialty Matt Kleszezynski Hydrotherm and Stephanie DePugh Thermo Pride Last but certainly not
5. Contents ix Other Automatic Controls Fan Controls Fan Control Air Switch Fan Relays Fan Center Fan Manager Fan Timer Switch Fan Safety Cutoff Switch Limit Controls Limit Control Secondary High Limit Switch Combination Fan and Limit Control Switching Relays Impedance Relays Heating Relays Time Delay Relays Potential Relay Pressure Switches Sail Switches Other Switches and Relays Sequence Controllers Contactors Troubleshooting Contactors Cleaning Contactors Replacing Contactors Motor Starter Overload Relay Heater Inherent Protector Pilot Duty Motor Protector Capacitors Troubleshooting Capacitors Replacing Capacitors High Pressure Cutout Switch Low Pressure Cutout Switch Transformers Sizing Transformers 233 233 233 236 237 239 241 241 242 244 244 248 251 256 259 261 263 265 266 268 269 275 277 280 280 281 281 282 283 284 287 287 288 289 290 291 x Contents Chapter 7 Installing Transformers Control Panels Ducts and Duct Systems Codes and Standards Types of Duct Systems Perimeter Duct Systems Extended Plenum Systems Crawl Space Plenum Systems Duct Materials Duct System Components Supply Air Registers Grilles and Diffusers Return Air and Exhaust Air Inlets Duct Run Fittings Air Supply and Venting Duct Dampers Damper Motors and Actuators Installing Damper Motors Troubleshooting Damper Motors Blowers or Fans for Duct Systems Designing a Duct
6. System Duct System Calculations Duct Heat Loss and Gain Air Leakage Duct Insulation Equal Friction Method Balancing an Air Distribution System Duct Maintenance Roof Plenum Units Mobile Home Duct Systems Proprietary Air Distribution Systems Duct Furnaces Electric Duct Heaters 291 293 295 295 295 296 297 297 298 299 301 302 303 305 305 313 316 320 321 322 323 324 325 325 326 331 331 332 333 336 338 347 Chapter 8 Contents xi Pipes Pipe Fittings and Piping Details 355 Types of Pipe Materials Wrought Iron Pipe Wrought Steel Pipe Galvanized Pipe Copper and Brass Pipes and Tubing Plastic Tubing Synthetic Rubber Hose Composite Tubing Pipe Fittings Classification of Pipe Fittings Extension or Joining Fittings Reducing or Enlarging Fittings Directional Fittings Branching Fittings Shutoff or Closing Fittings Union or Makeup Fittings Flanges Pipe Expansion Valves Pipe Threads Pipe Sizing Sizing Steam Pipes Sizing Hot Water Hydronic Pipes Tubing Pipe Fitting Measurements Calculating Offsets First Method Second Method Third Method Fourth Method Pipe Supports Joint Compound Pipe Fitting Wrenches Pipe Vise 355 356 363 363 363 367 369 369 369 370 370 378 380 380 382 382 382 382 384 384 384 385 393 396 397 400 401 401 403 403 403 406 409 xii Contents Chapter 9 Installation Methods Pipe Cutting Pipe Threading Pipe Ream
7. Trap Maintenance 520 Automatic Heat Up 520 Installing Steam Traps 522 Float Traps 523 Thermostatic Traps 524 Balanced Pressure Thermostatic Steam Traps 525 Maintenance 526 Float and Thermostatic Traps 526 Thermodynamic Steam Traps 529 xiv Contents Appendix A Appendix B Appendix C Appendix D Index Bucket Traps Flash Traps Impulse Traps Tilting Traps Lifting Traps Boiler Return Traps Expansion Tanks Closed Steel Expansion Tanks Diaphragm Expansion Tanks Sizing Expansion Tanks Troubleshooting Expansion Tanks Air Eliminators Pipeline Valves and Controls Temperature Regulators Electric Control Valves Regulators Water Tempering Valves Hot Water Heating Control Flow Control Valve Electric Zone Valve Balancing Valves Valve Adapters and Filters Manifolds Pipeline Strainers Professional amp Trade Associations Manufacturers Data Tables Conversion Tables 530 534 534 536 537 537 540 541 543 543 544 545 547 548 548 550 554 558 559 561 564 565 567 579 591 629 639 Introduction The purpose of this series is to provide the layman with an introduc tion to the fundamentals of installing servicing troubleshooting and repairing the various types of equipment used in residential and light commercial heating ventilating and air conditioning HVAC systems Consequently it was written not only for the HVAC tech nician and others with the required experience and skills to do this
8. a Tighten all connections and fittings in the intake line and unused intake port plugs see Figure 1 10 b Loosen mounting screws and shift fuel pump to a position where noise is eliminated Retighten mounting screws c Work in gears by continued running or replace continued 32 Chapter Table l 3 continued Symptom and Possible Cause Possible Remedy Pulsating pressure a Air leak in intake line a Tighten all fittings and valve packing in intake line b Air leaking around strainer b Tighten strainer cover screws cover c Partially clogged strainer c Remove and clean strainer d Partially clogged filter d Replace filter element Low oil pressure a Nozzle capacity is greater a Replace fuel pump with one of than fuel pump capacity correct capacity b Defective gauge b Check against another and replace if necessary Improper nozzle cutoff a Filter leaks a Check face of filter cover and gasket for damage b Partially clogged nozzle b Clean strainer or change nozzle strainer c Air leak in intake line c Tighten intake fittings and packing nut on shutoff valve tighten unused intake port plug d Strainer cover loose d Tighten screws e Air pockets between cutoff e Start and stop burner until valve and nozzle smoke and afterfire disappear Fuel Supply Tank and Line The installation maintenance and troubleshooting of fuel supply t
9. per centage of carbon dioxide in the flue gases and increase the stack temperature Oil Burners 47 Figure l 43 Bacharach Fyrite CO indicator Courtesy Bacharach Instrument Co Push rubber connecter down then Turn bottom side up and back again 3 Read fluid level on scale for percent squeeze bulb 18 times age of gas Figure l 44 CO test Courtesy Bacharach Instrument Co 48 Chapter For the most efficient operating characteristics the overfire draft generally should be not less than 0 02 inch wg Smoke and odor often occur when the overfire draft falls below 0 02 inch wg It may be necessary to adjust the barometric draft regulator to obtain the correct overfire draft If it is not possible to adjust the overfire draft for a 9 01 to 0 02 inch wg install a mechanical draft inducer between the chimney and the barometric draft regulator The primary air band should be adjusted to a 0 smoke or until a hard clean flame is visible A clean flame is preferred to one with high carbon dioxide Adjust the overfire draft for a 9 01 to a 9 02 inch wg An excessive overfire draft condition will cause high stack temperature and inefficient operation A too low or positive draft over the fire will usually cause the flue gases and fumes to seep into the space upon startup or shutdown The flue pipe draft in most residential oil burners is between 0 04 and 0 06 inches of water This is sufficient to maintain a draft of 0 02 inches
10. provides for automatic air purging on a two pipe system providing for fast cutoff 24 Chapter A Single stage unit PRESSURE ANTI HUM DEVICE GAUGE EASY FLOW BLEED VALVE STRAINER i eU TO NOZZLE BLEED ORIFICE TO TANK el LEGEND NC BYPASS TO SUCTION t PRESSURE REGULATING AND CUT OFF VALVE OIL RETURNED TO STRAINER CHAMBER OIL UNDER PRESSURE B Circuit diagram of single stage circuit Figure l 24 Circuit diagram of a single stage fuel pump Courtesy Sundstrand Hydraulics Oil Burners 25 Two Stage Pump A two stage pump has two sets of pumping gears These pumps are used in installations with underground tanks where the combina tion of lift horizontal run fittings and filters does not exceed the manufacturer s rating in inches of vacuum A major advantage of a two stage fuel unit is that all air is elim inated from the oil being delivered to the nozzle The inlet of the first stage is located above the inlet for the second stage As a result any air drawn into the fuel unit after priming is picked up by the first stage and discharged to the tank before it reaches the second stage Consequently the second stage draws completely air free oil As the air is being discharged into the tank by the first stage pressure begins to build up in the second stage causing the regulat ing valve to bypass excess oil back into the strainer These operating principles are illustrated by the circui
11. the fuel unit is operating properly The probable cause of improper cut off in those cases where a gauge reading is obtained is usually air in the system Priming Fuel Pumps On occasion the oil burner may fail to pump oil When this occurs check the oil supply line to the furnace for leaks If there are no leaks it may be necessary to prime the fuel pump Pumps are self priming for single stage two pipe systems and for two stage pumps A single stage pump one pipe system should be primed as follows I Turn off the electrical power supply to the unit 2 Read and follow the priming instructions provided by the manufacturer 3 Prime the pump until the oil is free of bubbles When a new pump fails to prime it may be due to dry pump conditions which can be corrected by removing the vent plug and filling the pressure cavity slowly so that the fuel oil wets the gears see Figure 1 29 Other possible causes of the pump failing to prime include the following e Suction inlet vacuum is greater than 15 inches of vacuum e Suction line is incorrectly sized e Oil suction line strainer or filter capacity does not match the pump suction gear capacity Bypass plug is not in position on two pipe installations Plug s and or suction line connections are not airtight Adjusting Fuel Pump Pressure The oil pressure regulator on the fuel pump is generally factory set to give nozzle oil pressures of 100 psig The firing rate is indic
12. 6 MM Figure I 11 Typical fuel Pump Courtesy Lennox Industries Inc the line depends on the size and capacity of the oil burner and the purpose for which it is used For example residential oil burners require 80 to 125 psi whereas commercial and industrial oil burn ers operate on 100 to 300 psi As the fuel oil passes through the nozzle it is broken up and sprayed in a very fine mist The air supply is drawn in through the inlet air scoop opening see Figure 1 5 and forced through the draft tube portion of the casing by the combustion air blower This air mixes with the oil spray after passing through a set of vanes 12 Chapter AIR AIR CASE OR ELECTRODES ADJUSTMENT ENTRANCE HOUSING BRACKET Fj NOZZLE TUBE NOZZLE Le a Zee FAN SSP N ELECTRIC NOZZLE MOTOR STRAINER SO CALLED ROTARY IGNITION ONE PIPE TURBULATOR ELECTRODES STRAINER OIL LINE VANES OIL SUPPLY PUMP CUTOFF VALVE LINE FROM BYPASS PRESSURE TANK AROUND PUMP RELIEF VALVE Figure l 12 Schematic of a gun type oil burner called a turbulator The turbulator gives a twisting motion to the air stream just before it strikes the oil spray producing a more thor ough mixture of the oil and air see Figure 1 13 Ignition of the oil spray is provided by a transformer that changes the house lighting current and feeds it to the electrodes to provide a spark at the beginning of each operating period TURBULATOR AIR CONE ELECTRODE WAIN 7 77 0
13. ARY AIR Ne PRIMARY AIR BALL OIL FEED INLET BEARINGS TIP Figure I 17 Elementary rotary cup oil burner opening of the casing the oil is met by the surrounding blast of primary air with which it mixes giving the proper mixture for combustion Vaporizing Pot Type Oil Burners Figures 1 19 and 1 20 show a typical vaporizing pot type oil burner The fuel oil is vaporized for combustion by heating it from below The vaporized fuel oil rises vertically where it is burned at the top The following are the two basic types of vaporizing or pot oil burners 1 The natural draft pot burner 2 The forced draft pot burner In the former the air necessary for combustion is provided by the chimney The forced draft pot burner relies on both the chim ney and a mechanical device e g a fan for the air supply Sleeve burners also referred to as perforated sleeve burners rep resent a third type of vaporizing or pot burner Although these burners are used mostly in conjunction with small oil fired equip ment e g kitchen ranges and space heaters they can also be employed to heat a small house if outside temperatures do not become too low Combination Oil and Gas Burners Some oil burners are available with combination oil and gas firing accessories that make it possible to use either of these fuels in the Oil Burners 19 CENTRIFUGAL FORCE INCREASING RIM OF CUP A B sar OIL DROPLETS FLATTENED INTO FILM
14. Audel HVAC Fundamentals Volume 2 Heating System Components Gas and Oil Burners and Automatic Controls All New 4 Edition James E Brumbaugh WILEY Wiley Publishing Inc Vice President and Executive Group Publisher Richard Swadley Vice President and Executive Publisher Robert Ipsen Vice President and Publisher Joseph B Wikert Executive Editor Carol A Long Acquisitions Editor Katie Feltman Editorial Manager Kathryn A Malm Senior Production Manager Fred Bernardi Development Editor Kenyon Brown Production Editor Vincent Kunkemueller Text Design amp Composition TechBooks Copyright 2004 by Wiley Publishing Inc Indianapolis Indiana All rights reserved Published simultaneously in Canada No part of this publication may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photocopying recording scanning or otherwise except as permitted under Section 107 or 108 of the 1976 United States Copyright Act without either the prior written permission of the Publisher or authorization through payment of the appro priate per copy fee to the Copyright Clearance Center Inc 222 Rosewood Drive Danvers MA 01923 978 750 8400 fax 978 646 8700 Requests to the Publisher for permission should be addressed to the Legal Department Wiley Publishing Inc 10475 Crosspoint Blvd Indianapolis IN 46256 317 572 3447 fax 317 572 4447 E mail permcoor
15. CTORY FIREPOT TRANSFORMER AIR TUBE Figure l 3 Gun type oil burner firing into furnace combustion chamber Courtesy U S Department of Agriculture e Vertical rotary burners e Horizontal rotary burners e Wall flame rotary burners Gun Type Oil Burners Gun type high pressure atomizing oil burners are sometimes called sprayers or atomizing burners because they spray the fuel oil instead of vaporizing it They are also referred to as gun or pressure oil burners because the oil is forced under pressure through a special gun like atomizing nozzle The liquid fuel is broken up into minute liquid particles or globules to form the spray Construction Details The principal components and parts of a gun type high pressure atomizing oil burner used in residential and light commercial oil heating systems are illustrated in Figures 1 6 and 1 7 The 4 Chapter Figure l 4 Cutaway view of a vertical rotary burner of the vaporizing or wall flame type Courtesy Integrated Publishing construction details of gun type oil burners will vary somewhat in different makes and models but the overall design of these burners is now nearly standardized The components and parts of a typical gun type oil burner can be divided into the following categories Oil Burners 5 FUEL TUBE TIP STATIONARY PRIMARY OIL SWIRLS IN AIR COUNTERCLOCKWISE DIRECTION AUTOMIZING CUP ROTATING FAN FUEL TUBE HO
16. Damaged electrodes are not the only cause of puffback Other causes include the following e Ignition transformer failure e Contaminated or eroded oil burner nozzle e Fuel pump malfunction e Clogged oil filter e Clogged burner air intake e Damaged combustion chamber linings Oil Burners 37 30 TO 60 N SUIS SISSIES Figure I 35 Spray angles 30 to 60 suitable for long narrow chambers Courtesy Wayne Home Equipment Co Inc Troubleshooting Electrodes The gun assembly must be removed from the oil burner in order to inspect the electrodes The following conditions require electrode replacement e Cracks in the electrode coating e Dull electrode points e Broken electrodes Servicing Electrodes Remove the electrodes by loosening the screw connecting them to the gun assembly If the electrodes are round and appear worn use a file to reestablish a good point Reinstall them in the electrode holder and set the electrode gap at 2 inch Set the distance between the center of the nozzle and the tips at inch Broken electrodes or electrodes with cracked ceramic coatings must be replaced with new ones Oil Burner Air System The air system for the average oil burner is generally composed of the air shutter draft tube the turbulator and the fan The draft tube and turbulator have already been shown see Figures 1 2 and 1 12 The fan construction consists of a squirrel cage series of vanes or blade
17. GE OPERATING j INLET CONNECTION amp a _ J INLET LINE RETURN LINE WHEN USED TWO PIPE Figure l 26 Attachment of vacuum and pressure gauge Courtesy Wayne Home Equipment Co Inc 28 Chapter 75 90 PSI cutoff point should hold If pressure drops back to zero indicates leaky cutoff T f INLET LINE 1 f RETURN LINE Figure l 27 Pressure gauge attached to the nozzle line Courtesy Wayne Home Equipment Co Inc A system with an oil supply tank located below the level of the oil burner that supplies the fuel oil through a line filter must pro duce a reading on the vacuum gauge if the system is operating prop erly A zero reading will indicate the presence of an air leak Table 1 3 lists a few of the problems that may be encountered with fuel units and some suggested remedies for dealing with them Most manufacturers of fuel units or gauges generally supply trou bleshooting recommendations along with the installation and maintenance instructions The cause of improper cutoff can be determined by inserting a pressure gauge in the nozzle port of the fuel unit see Figure 1 28 F f A Figure l 28 Checking fuel pressure with a gauge Courtesy Sundstrand Corp Oil Burners 29 Allow the fuel unit to operate for a few minutes and then shut off the burner If the pressure drops to 0 psi on the gauge the fuel unit should be replaced A gauge reading above 0 psi indicates that
18. LLOW MAIN SHAFT AIR SWIRLS IN tee CLOCKWISE DIRECTION NOZZLE BAFFLE PROTECTOR PLATE Figure l 5 Horizontal rotary burner Courtesy Integrated Publishing l Burner control 2 Primary safety control 3 Gun assembly 4 Ignition transformer 5 Burner motor and coupling 6 Fuel pump 7 Combustion air blower Burner Control The burner control is the operational control center of the burner As shown in Figures 1 6 and 1 7 it is located on the right side of the burner assembly directly above the combustion air blower housing It operates in conjunction with the primary control and a bimetallic 6 Chapter HIANGE AIR TUBE GASKET pange SCREWS HOLE PLUG ELECTRONIC IGNITION AIR TUBE TRANSFORMER ee ASSY FOR FB HEADS MAIN HOUSING ASSY CI ESCUTCHEON PLATE CONNECTOR FB HEAD TUBE HEAD INSULATOR NOZZLE ADAPTER NOZZLE LINE ELECTRODE HEAD ELECTRODE ASSY ASSY Figure l 6 Typical gun type oil burner side view Courtesy Lennox Industries Inc temperature sensor When the room thermostat calls for heat and the ignition cycle begins the burner control will start the burner only when the cad cell detects proves a flame The burner control shuts off the burner if the cad cell fails to prove the flame or if the bimetallic sensor detects a temperature too high for safe operation Primary Safety Control The primary safety control is an automatic safety device designed to stop the f
19. SPRING a 5 N erent 11 N x N N N a yr VS N N PISTON NY a N N N AN RETURN TO TANK NT eS N TWO PIPE N N VS A VS N common N N STEM PRESSURE RELIEF ATRAN YTA IN VALVE N SS N STOP N A N N X N N vwe N FLANGE N N VALVE N PUMP ACTIVATING N SPRING R N NOZZLE N N MAXIMUM N N VALVE s N LIFT C PRESSURE CUTOFF RELIEVING SLOT VALVE Figure I 15 Schematic sectional view of combined cutoff valve and pressure relief valve showing the strainer fuel pump and piping locations valve The strong piston spring tends to move the piston downward and close the pressure relief valve and then the cutoff valve When the pump starts and the pressure in the cylinder below the piston rises to about 60 lbs depending on the piston spring setting the piston and the two valves i e the cutoff and pressure relief valve rise until the valve flange contracts with the stop At this 16 Chapter instant the cutoff valve is fully opened allowing oil to flow to the nozzle the pressure relief valve still being closed Since the nozzle does not have sufficient capacity to discharge all the oil that is sup plied by the pump the pressure below the piston will continue to rise Flame Retention Head Burners Most oil furnaces and boilers prior to 1980 were installed with cast iron head burners that had an efficiency rating of only about 60 percent The efficiency of these cast iron head burne
20. ack temperature may be caused by any of the following e Undersized furnace e Defective combustion chamber e Incorrectly sized combustion chamber e Lack of sufficient baffling e Dirty heating surfaces e Excessive draft e Boiler or furnace overfired 46 Chapter Figure 1 42 Running a stack gas temperature test with a stack thermometer Courtesy Bacharach Instrument Co e Unit unsuited to automatic firing e Draft regulator improperly adjusted When the carbon dioxide CO content of the flue gas is too low less than 8 percent heat is lost up the chimney and the unit operates inefficiently This condition is usually caused by one of the following e Underfiring the combustion chamber e Burner nozzle is too small e Air leakage into the furnace or boiler When the carbon dioxide content is too high the furnace opera tion is generally characterized by excess smoke and or pulsations and other noises A high carbon dioxide content is usually caused by insufficient draft or an overfired burner The carbon dioxide reading is also taken through a hole drilled in the flue pipe with a CO indicator see Figure 1 43 The CO indicator is used as shown in Figure 1 44 The results are indicated by a test liquid on a scale calibrated in CO A correct draft is essential for efficient burner operation Insufficient draft can make it almost impossible to adjust the oil burner for its highest efficiency Excessive draft can reduce the
21. anks is described in Chapter 12 il Furnaces in V olume 1 Oil Burner Nozzles An oil burner nozzle is a device designed to deliver a fixed amount of fuel to the combustion chamber in a uniform spray pattern and spray angle best suited to the requirements of a specific burner The oil burner nozzle atomizes the fuel oil i e breaks it down into extremely small droplets so that the vaporization necessary for combustion can be accomplished more quickly Oil Burners 33 The components in a typical nozzle see Figure 1 30 include the following I Orifice 2 Swirl chamber 3 Orifice disc 4 Body 5 Tangential slots 6 Distributor 7 Retainer 8 Filter Fuel oil is supplied under pressure 100 psi to the nozzle where it is converted to velocity energy in the swirl chamber by directing it through a set of tangential slots The centrifugal force caused within the swirl chamber drives the fuel oil against the chamber ORIFICE DISTRIBUTOR BODY TANGENTIAL SLOTS RETAINER Figure I 30 Details of an oil burner nozzle Courtesy Wayne Home Equipment Co Inc 34 Chapter walls producing a core of air in the center The latter effect moves the oil out through the orifice at the tip of the nozzle in a cone shaped pattern The following are the two basic spray cone patterns 1 The hollow cone 2 The solid cone Each has certain advantages depending on its use The hollow cone pattern see Figur
22. ated on the nameplate and can be obtained with standard nozzles by adjusting the pump pressures as follows I Turn the adjusting screw clockwise to increase pressure 2 Turn the adjusting screw counterclockwise to decrease pressure 3 Never exceed the pressures indicated in Table 1 2 30 Chapter RETURN PORT TO VENT PUMP V4 pipe thread used TO ADJUST PRESSURE Attach 14 ID as return on two remove cover plug of plastic tube pipe installation pressure adjusting Use 7s wrench May be used as port located behind to open vent Vs optional inlet or inlet port Insert turn maximum vaccum test port standard screwdriver on single pipe turn counter FOR USE AS installation clockwise to below GAGE PORT pressure desired remove plug to Turn clockwise to set install 1 4 pipe to desired pressure threaded gage sw Remove insert to EA D install Ys pipe ag INLET PORT threaded gage WEBSTER ELECTRIC NOZZLE PORT Racine wisconsin a sta rite industry Ve pipe thread nee BYPASS PLUG full unit 1725 RPM Vie pipe thread 6a allen Insert by pass Access through plug for two pipe bottom inlet system thru bottom inlet AN INLET PORT 1 4 pipe thread COLOR OF PRINTING DENOTES OPERATING SPEED BLUE 1725 RPM GREEN 3450 RPM INLET PORT 1 4 pipe thread Figure 1 29 Webster model M series fuel pump Courtesy Webster Electrical Co Inc Table l 2 Maximum Recommende
23. d Pressures Bonnet Firing Standard Pump Capacity Rate Nozzle Pressure 1000 Btu h gph Size psig 85 0 76 0 75 103 100 0 90 0 90 100 125 1 12 1 10 104 150 1 35 1 35 100 200 1 80 1 75 112 250 225 2 25 100 333 3 00 1 50 100 Courtesy Carrier Corp Oil Burners 31 Troubleshooting Fuel Pumps The troubleshooting list in Table 1 3 contains the most common operating problems associated with fuel pumps and fuel units Each problem is given in the form of a symptom the possible cause and a suggested remedy The purpose of this list is to provide the opera tor with a quick reference to the cause and correction of a specific problem Table l 3 Troubleshooting Fuel Pumps Symptom and Possible Cause Possible Remedy No oil flow to nozzle a Clogged strainer or filter b Air binding in two pipe system c Frozen pump shaft a Remove and clean strainer repack filter element b Check and insert bypass plug c Remove pump and return it to the manufacturer for repair or replacement Oil leak a Loose plugs or fittings a Dope with good quality thread b Leak at pressure adjusting end cap nut c Blown seal d Seal leaking sealer b Fiber washer may have been left out after adjustment of valve spring replace washer c Replace fuel unit d Replace fuel unit Noisy operation a Air inlet line b Bad coupling alignment c Pump noise
24. d to service a fuel unit With these two gauges the individual can check the following e e Vacuum Lift Air leaks Pressure Cutoff Delivery Figures 1 26 and 1 27 illustrate the attachment of the vacuum and pressure gauges to a fuel unit The pressure gauge shown as Oil Burners 27 the upper gauge in Figure 1 26 and the gauge attached to the noz zle line opening in Figure 1 27 will indicate whether a positive cutoff is operable or whether an adequate and uniform buildup of pressure is present When the pressure gauge is attached to the nozzle line opening it should indicate a reading of 75 to 90 psi see Figure 1 27 Any drop of the pressure gauge reading to zero indicates leaky cutoff and probable difficulty with the shutoff valve in the nozzle line The existence of air leaks in the supply line can be determined by vacuum gauge readings once the gauge is attached to the optional inlet connection see Figure 1 26 An evaluation of the gauge read ing is itself determined by the location of the oil storage tank If the tank is located above the burner and the oil is supplied by gravity flow the vacuum gauge must show a reading of zero unless there is a problem in the system These problems can take the following forms e A partially closed cutoff valve of the oil supply tank e A kinked or partially blocked oil supply line e A blocked line filter PRESSURE GAUGE 100 PSI OPERATING gt PRESSURE VACCUM GAU
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26. e use instruments to adjust the fire Air Delivery and Blower Adjustment It is sometimes necessary to adjust the blower speed to produce a temperature rise through the furnace that falls within the limits stamped on the furnace nameplate Blower adjustment procedures are described in Chapter 11 Gas Furnaces of V olume 1 Combustion Testing and Adjustments The following instruments are recommended for combustion test ing and adjustments e Draft gauge e Smoke tester e Carbon dioxide tester e 200 1000F stack thermometer e 0 150 psig pressure gauge e 0 30 inch mercury vacuum gauge Smoky combustion indicates poor burner performance The amount of smoke in the flue gas can be measured with a smoke tester see Figure 1 40 The tube of the smoke tester is inserted through a inch hole drilled in the flue pipe and the test is run as shown in Figure 1 41 Any smoke in the air drawn into the smoke tester will register on a filter paper inserted in the device The results are interpreted according to the smoke scale in Table 1 5 One of the most common causes of smoky combustion is soot for mation on the heating surfaces This is easily corrected by cleaning Other possible causes of smoky combustion include the following e Insufficient draft e Poor fuel supply e Fuel pump malfunctioning Defective firebox Incorrectly adjusted draft regulator Defective oil burner nozzle e Wrong size oil burner nozzle 44 Chapter Fi
27. e 1 31 is recommended for use in smaller burners those firing 1 00 gph and under As shown in Figure 1 31 they are characterized by a concentration of fuel oil droplets all around the outer edge of the spray There is little or no distribution of droplets in the center of the cone The principal advantage of the hollow cone patterns is a more stable spray pattern and angle under adverse conditions than solid cone patterns operating under the same conditions and at the same flow rate The solid cone pattern illustrated in Figure 1 32 is character ized by a uniform or near uniform distribution of fuel oil droplets throughout the cone pattern Nozzles producing this cone pattern are particularly recommended for smoother ignition in oil burners firing above 2 00 or 3 00 gph They are also recommended where long fires are required or where the air pattern or the oil burner is heavy in the center A combination cone pattern that is neither a true cone nor a true hollow cone can be used in oil burners firing between 0 40 gph and 8 00 gph Figure I 31 Hollow spray cone pattern Courtesy Wayne Home Equipment Co Inc Oil Burners 35 Figure 1 32 Solid spray cone pattern Courtesy Wayne Home Equipment Co Inc Oil burner nozzles are also selected on the basis of the spray angle they produce see Figure 1 33 The spray angle refers to the angle of the spray cone and this angle will generally range from 30 to 90 The angle selected
28. ermostats 134 Humidistats 134 Location of Room Humidistats 140 Troubleshooting Humidistats 142 Chapter 5 Gas and Oil Controls 145 Gas Controls 145 Gas Control Circuits 146 Gas Burner Primary Control 146 Servicing a Gas Burner Primary Control 151 Gas Valves 153 Solenoid Gas Valves 153 Solenoid Coils 158 Direct Acting Heat Motor Valves 163 Diaphragm Valves 164 Pressure Regulators 166 Pressure Switches 170 viii Contents Automatic Pilot Safety Valve Thermopilot Valves Thermocouples Troubleshooting Thermocouples Thermopiles Pilot Generators Pilot Operated Diaphragm Valves Combination Gas Valves Standing Pilot Combination Gas Valves Continuous Pilot Dual Automatic Gas Valve Universal Electronic Ignition Combination Gas Valve Pilot Burners Installing a Pilot Burner Replacing the Pilot Burner Orifice Lighting the Pilot Pilot Flame Adjustment Main Burner Ignition Pilot Pressure Switch Electronic Ignition Modules Intermittent Pilot Ignition Module Direct Spark Ignition Module Hot Surface Ignition Module Igniters Flame Sensors Mercury Flame Sensors Oil Controls Oil Valves Oil Burner Primary Control Cadmium Cell Primary Controls Stack Detector Primary Control Combination Primary Control and Aquastat Troubleshooting the Oil Burner Primary Control 174 178 181 183 184 185 187 187 191 194 194 198 200 201 202 202 203 203 204 207 208 211 214 216 217 217 219 220 223 227 231 Chapter 6
29. gure 1 40 Bacharach true spot smoke tester Courtesy Bacharach Instrument Co Insert filter test paper into Withdraw gas sample from Grade soot spot test paper TRUE SPOT flue pipe by 10 pump strokes by comparison with shadings on scale Figure l 41 A smoke tester in use Courtesy Bacharach Instrument Co Oil Burners 45 Table 1 5 Smoke Scale Bacharach Smoke Scale No Rating Sooting Produced 1 Excellent Extremely light if at all 2 Good Slight sooting which will not increase stack 3 Fair May be some sooting but will rarely require cleaning more than once a year 4 Poor Borderline condition some units will require cleaning more than once a year 5 Very poor Soot produced rapidly and heavily Courtesy Bacharach Instrument Co e Improper fan delivery e Excessive air leaks in boiler or furnace e Unsuitable fuel air ratio Net stack temperatures in excess of 700F for conversion units and 500F for packaged units are considered abnormally high The net stack temperature is the difference between the temperature of the flue gases inside the pipe and the room air temperature outside For example if the flue gas temperature is 600F and the room tem perature is 75F then the net stack temperature is 525F 600F 75F S25F A 200 1000F stack thermometer is used to measure the flue gas temperature The thermometer stem is inserted through a hole drilled in the flue pipe see Figure 1 42 A high st
30. hdd LA RM Ak hhh hod hE DRAFT TUBE JET LINE Figure l 13 Details of draft tube illustrating the location of the turbulator air cone and electrode Oil Burners 13 The starting cycle of the oil burner is initiated by the closing of the motor circuit When the motor circuit is closed automatically by room temperature control the motor starts turning the fan and the pump At the same time the ignition transformer produces a spark at the electrodes ready to light the oil and air mixture The action of the pump draws the fuel oil from the tank through the strainer on the fuel line Its flow is controlled by an oil cutoff valve which prevents oil passing to the nozzle unless the pressure is high enough to spray the oil approximately 60 Ibs of pressure Because the pump in the oil burner pumps oil much faster than it can be discharged through the nozzle at that pressure i e 60 lbs of pressure the oil pressure continues to rise very fast between the pump and the nozzle When the pressure begins to rise above the normal operating pressure 100 Ibs a pressure relief valve opens and allows the excess oil to flow through the bypass line to the inlet as in the so called one pipe system or to flow through a sec ond or return line to the supply tank The pressure relief valve in either system maintains the oil at the correct operating pressure When the oil burner is turned off i e when the burner motor stops the oil pressure quic
31. in the firebox The furnace or boiler draft is measured with a draft gauge as shown in Figure 1 45 A hole is drilled in either the fire door overfire draft measurement or flue pipe flue pipe draft measurement and the unit is run for approximately 5 minutes The draft tube is then inserted into the test hole and the gauge is read see Figure 1 46 Troubleshooting Oil Burners Individuals involved in the installing and repairing of oil burners should be aware of a number of different indicators of malfunc tions in the equipment their probable causes and some suggested remedies Figure 1 45 Bacharach model MZF draft gauge Courtesy Bacharach Instrument Co Oil Burners 49 A Overfire draft B Flue pipe draft Figure 1 46 Overfire and flue pipe draft tests Courtesy Bacharach Instrument Co The average individual is most aware of malfunctions that warn the senses through excessive noise smoke or odor These are external warning signals that require immediate investigation Their nature is such that tracing the probable cause of the malfunction is made easier Excessive noise pulsation thumping rumbling etc in the heat ing unit is generally caused by a problem with the oil burner nozzle It can usually be corrected by any one of the following methods e Replace the nozzle with one having a wider spray angle e Replace the nozzle with one having the next size smaller opening e Install a delayed ope
32. ing Pipe Cleaning Pipe Tapping Pipe Bending Assembling and MakeUp Nonferrous Pipes Tubing and Fittings Soldering Pipe Brazing Pipes Braze Welding Pipe Welding Pipe Gas Piping Insulating Pipes Piping Details Connecting Risers to Mains Connections to Radiators or Convectors Lift Fittings Drips Dirt Pockets Siphons Hartford Connections Making Up Coils Relieving Pipe Stress Swivels and Offsets Eliminating Water Pockets Pressure Tests Valves and Valve Installation Valve Components and Terminology Valve Materials Globe and Angle Valves Gate Valves Check Valves 410 410 412 414 414 414 415 415 420 420 424 425 425 429 429 430 431 431 431 432 434 434 434 434 436 439 440 444 445 445 451 454 456 458 Contents xiii Stop Valves 463 Butterfly Valves 465 Two Way Valves 467 Three Way Valves 469 Y Valves 469 Valve Selection 469 Troubleshooting Valves 472 Valve Stuffing Box Leakage 474 Valve Seat Leakage 474 Damaged Valve Stems 475 Automatic Valves and Valve Operators 475 Valve Pipe Connections 487 Valve Installing Pointers 489 Soldering Brazing and Welding Valves to Pipes 492 Soldering or Silver Brazing Procedure 494 Butt Welding Procedure 495 Socket Welding Procedure 496 Chapter 10 Steam and Hydronic Line Controls 497 Steam and Hydronic System Pumps 497 Condensate Pumps 497 Circulators Water Circulating Pumps 505 Circulator Selection 511 Steam Traps 518 Sizing Steam Traps 519 Steam
33. ing the motor lead from the burner and allowing the ignition circuit to be ener gized Figures 1 38 and 1 39 illustrate two typical wiring diagrams for primary safety controls Installing an Oil Burner Under most circumstances oil burners and oil fired units should be installed in rooms that provide adequate clearance from the com bustible material The only exception to this rule is when specific instructions are given otherwise In this case the manufacturer pro oo CAD CELL FLAME DETECTOR PRIMARY CONTROL IGNITION TRANSFORMER THERMOSTAT BURNER HOT MOTOR GND For color code or terminal marking refer to wiring diagram inside primary control cover Figure l 38 Constant ignition wiring diagram Courtesy Stewart Warner Corp Oil Burners 41 CAD CELL FLAME DETECTOR PRIMARY CONTROL IGNITION TRANSFORMER THERMOSTAT HOT GND For color code or terminal marking refer to wiring diagram inside primary control cover Figure 1 39 Intermittent ignition wiring diagram Courtesy Stewart Warner Corp vides or specifies a suitable combustion chamber stainless steel firebrick etc Note All local codes and ordinances take precedence over the oil burner manufacturer s installation and operation manuals Where local codes do not exist install the oil burner in accordance with the most recent instructions and regulations of the National Fire Protection Association and
34. kly drops below the operating pressure and a pressure relief valve closes The flame continues until the pressure drops below the setting of the cutoff valve The cutoff and pressure relief regulating valves may be either two separate units or combined into one unit Figure 1 14 shows the essentials of the two unit arrangement These are as shown simply elementary schematics designed to illustrate basic operating principles The cutoff needle valve is shown with a spring inside the bellows and the pressure relief mushroom valve is shown with exposed spring In the cutoff valve arrangement the spring acts against oil pressure on the head of the bellows tending to collapse it in the pressure relief valve the spring acts against the oil pres sure which acts on the lower face of the mushroom valve tending to open it When the pump starts and the pressure in the line rises to about 60 Ibs depending on the spring setting this pressure acting on the head of the bellows overcomes the resistance of the spring causing the cutoff valve to open Since the pump supplies more oil than the nozzle can discharge the pressure quickly rises to 100 Ibs over coming the resistance of the relief valve spring and causing the valve to open This allows excess oil to bypass or return to the tank The relief valve will open high enough to maintain the working pressure constant at 100 lbs When the oil burner is turned off the oil pressure quickly drops
35. l oil to be used The heavier the grade of fuel oil used in an oil burner the greater the care that must be taken to ensure that the oil is delivered for combustion at the proper atomizing temperature If the oil is not maintained at this temperature prior to delivery for combustion the oil burner will fail to operate efficiently An efficient oil burner is one that burns the fuel oil completely using the smallest amount of air necessary for combustion Oil Burners 23 SHAFT SEAL BODY PUMPING GEARS STRAINER SHAFT BEARING NOISE DAMPENING DEVICE CUTOFF VALVE BLEED VALVE Figure l 23 Cutaway view of a single stage fuel pump Courtesy Sundstrand Hydraulics The fuel oil first enters the unit by passing through the strainer where foreign particles such as dirt and line filter fibers are removed The fuel oil then moves through the hydraulically bal anced pumping gears and is pumped under pressure to the valve see circuit diagram in Figure 1 24 The pressure forces the piston away from the nozzle cutoff seat and the fuel oil then flows out the nozzle port Oil in excess of nozzle capacity is bypassed through the valve back to the strainer chamber in a single pipe system or is returned to the tank in a two pipe system Pressure is reduced on the head of the piston when the pump motor is shut off At this point the piston snaps back causing the nozzle port opening to close A bleeder valve opening in the piston
36. least I would like to thank Katie Feltman Kathryn Malm Carol Long Ken Brown and Vincent Kunkemueller my editors at John Wiley amp Sons whose constant support and encouragement made this project possible James E Brumbaugh XV About the Author James E Brumbaugh is a technical writer with many years of expe rience working in the HVAC and building construction industries He is the author of the Welders Guide The Complete Roofing Guide and The Complete Siding Guide xvi Chapter Oil Burners An oil burner is a mechanical device used to prepare the oil for burning in heating appliances such as boilers furnaces and water heaters The term oil burner is somewhat of a misnomer because this device does not actually burn the oil It combines the fuel oil with the proper amount of air for combustion and delivers it to the point of ignition usually in the form of a spray The fuel oil is prepared for combustion either by vaporization or by atomization These two methods of fuel oil preparation are used in the three basic types of oil burners employed in commercial industrial and residential heating The following are the three basic types of oil burners Gun type atomizing oil burners 2 Vaporizing pot type oil burners 3 Rotary oil burners Gun type atomizing oil burners are available as either low pressure or high pressure types see Figures 1 1 1 2 and 1 3 Both are used in residential heating applicatio
37. low of fuel oil at the burner should ignition or flame failure occur Modern oil fired furnaces and boilers use a cad cell as the primary control to prove the flame older ones were equipped with a stack detector primary control The former is mounted inside the burner behind the access door see Figure 1 8 and the latter is located in the stack Gun Assembly The oil burner gun assembly consists of a burner nozzle the elec trodes and a tube connecting the electrodes to the fuel pump see Figure 1 9 The burner nozzle changes the fuel oil into a form that can be burned in the combustion chamber It accomplishes this by forcing the oil under pressure through a small hole at the end of the nozzle The atomized fuel oil is ignited by spark from the electrodes Oil Burners 7 ELECTRONIC IGNITION BURNER TRANSFORMER CONTROL RESET mad BUTTON REAR ACCESS DOOR GASKET ola VIEW PORT AIR REAR ACCESS ADJUSTMENT DOOR ASSY DIAL SPLINED Ba al Gi LO ORL INDIN e o pr OIL PUMP m BLOWER INLET COUPLING COMBUSTION AIR WHEEL AIR SCOOP MOTOR Figure l 7 Typical gun type oil burner front view Courtesy Lennox Industries Inc Ignition Transformer A step up ignition transformer located on top of the burner assem bly produces the voltage used by the electrodes to ignite the fuel oil This type of transformer is designed to increase the voltage
38. marks Wiley the Wiley Publishing logo and Audel are trademarks or registered trade marks of John Wiley amp Sons Inc and or its affiliates All other trademarks are the property of their respective owners Wiley Publishing Inc is not associated with any product or vendor mentioned in this book Wiley also publishes its books in a variety of electronic formats Some content that appears in print may not be available in electronic books Library of Congress Cataloging in Publication Data eISBN 0 7645 7436 1 Printed in the United States of America 10987654321 For Laura my friend my daughter Contents Introduction About the Author Chapter 1 Oil Burners Gun Type Oil Burners Construction Details Operating Principles Flame Retention Head Burners High Static Oil Burners Rotary Oil Burners Vaporizing Pot Type Oil Burners Combination Oil and Gas Burners Fuel Pump Single Stage Fuel Pump Two Stage Pump Fuel Pump Capacity Fuel Pump Service and Maintenance Priming Fuel Pumps Adjusting Fuel Pump Pressure Troubleshooting Fuel Pumps Fuel Supply Tank and Line Oil Burner Nozzles Electrodes Troubleshooting Electrodes Servicing Electrodes Oil Burner Air System Primary Safety Control Service Installing an Oil Burner Starting an Oil Burner Air Delivery and Blower Adjustment Combustion Testing and Adjustments Troubleshooting Oil Burners XV xvi 10 16 16 16 18 18 19 21 25 26 26 29 29 31 32 32 37 37
39. ning solenoid on the nozzle line this reduces pulsation Sometimes a noisy fire is caused by cold oil originating from out side storage tanks This noise may be greatly reduced or eliminated by pumping the fuel oil under 120 to 125 psi through the next size smaller nozzle Excessive smoke has a number of possible causes including the following e The air handling parts of the oil burner may be too dirty to operate efficiently 50 Chapter e The combustion chamber or burner tube may be damaged by burn through or loose materials e The oil burner nozzle may be the wrong size The dirty air handling parts e g the fan blades air intake and air vanes in the combustion head can be made to operate more effi ciently by a thorough cleaning If the excessive smoke is caused by the oil burner nozzle this can be corrected by replacing the nozzle with one that is a size smaller or one having the next narrower spray angle A damaged combustion chamber is a more difficult problem to correct than the other two In any event all leakage through the walls must be eliminated before the oil burner can be expected to operate efficiently Excessive odors can be caused by flue obstructions or poor chimney draft If the draft over the fire is lower than 0 02 to 0 04 it is usually an indication that the problem lies with the flue or chimney draft The cause is usually an obstruction in the flue or poor chimney draft Other causes of excessive od
40. ns with the latter being by far the more popular of the two The remainder of this chapter is devoted to a description of the gun type high pressure atomizing oil burners used in residential and light commercial oil heating systems Figure l I Basic shape of a gun type oil burner Courtesy Stewart Warner Corp 2 Chapter TRANSFORMER IGNITION AND FIRING ASSEMBLY PLATE OIL FEED TUBE FROM PUMP TO DRAFT TUBE PYPEX FIRE INSPECTION PUMP STRAINER AND VALVE UNIT BUILT IN MOTOR PROTECTOR MOTOR COUNTER BALANCED DRAFT SHUTTER FAN HOUSING LEGS FOR PEDESTAL MOUNTED ATTACHMENT Figure l 2 Principal components of an S T Johnson gun type oil burner Courtesy S T Johnson Company The advantage of the vaporizing pot type oil burner is its low operating cost It is the least expensive to use but it has limited heating applications It is currently used only in small structures located in milder climates Vaporizing burners can be divided into the three following types 1 Natural draft pot burners 2 Forced draft pot burners 3 Sleeve burners Rotary oil burners are commonly used in the heating systems of commercial or industrial buildings although they can and have been used for residential heating applications see Figures 1 4 and 1 5 The following types of rotary oil burners are available for heating purposes Oil Burners 3 FUEL LINE STRAINER AYN Bs PUMP REFRA
41. nt conditions of use In each case the operating principle involves throwing the oil by centrifugal force Rotary oil burners can be classified either as rotary nozzle or rotary cup burners The essential components of the rotary nozzle burner are shown in Figure 1 16 Air pressure acting on the pro Oil Burners 17 VAPOR Voge a id he aA Sis w 43 VAPORIZING RIM PROPELLER OIL DUCT Figure l 16 Elementary rotary nozzle oil burner peller causes the nozzle assembly to rotate at a very high speed Oil is supplied through the hollow shaft to the nozzles and the rotary motion causes the oil to be thrown off in a fine spray by centrifugal force The flame from this spray heats up the metal vaporizing rim hot enough to vaporize the oil spray as it comes in contact with it Being thoroughly mixed with air a blue flame is produced On some designs the spray vaporized by the vaporizing rim is super heated by passing through grilles The rotary cup oil burner see Figure 1 17 contains a cone shaped cup that rotates on ball bearings carried by a central tube The fuel is supplied to the cup through this tube In operation drops of oil issuing from the oil feed tip come into contact with the cup as shown by centrifugal force the drops are both flattened into a film and projected toward and off the rim of the cup as shown in Figure 1 18 Because the rim is surrounded by a concentric 18 Chapter OIL TUBE PROPELLER ROT
42. of a high voltage 110 VAC circuit to the ultrahigh 14 000 volts required to ignite the fuel oil Burner Motor and Coupling As shown in Figure 1 5 the burner motor is located on the right side of the oil burner assembly The drive shaft of the burner motor is connected to both the fuel pump and the combustion air blower by a coupling that functions as the drive shaft for both of these units A burner motor is also sometimes called an oil pump motor or a pump motor because it is connected to and drives the fuel oil pump 8 Chapter BURNER CONTROL CAD CELL FLAME DETECTOR LOCATED INSIDE BURNER ASSEMBLY FUEL PUMP COMBUSTION AIR BLOWER ASSEMBLY Figure l 8 Locations of burner control and cadmium cell primary safety control Fuel Pump The fuel pump also called an oil pump or a fuel unit is used to draw fuel oil from the storage tank and deliver it under high pres sure 100 to 140 psi to the nozzle assembly see Figure 1 11 It is driven by the burner motor and coupling and is located on the left side of the oil burner Combustion Air Blower The combustion air blower is also driven by the burner motor and coupling It is located between the burner motor and the fuel pump Its function is to introduce the required amount of air for the Oil Burners 9 NOZZLE ADAPTER IGNITION POINTS BAFFLE PLATE PORCELAIN INSULATORS ne SN ME ELECTRODE SPRINGS OIL TIGHT FITTINGS lt o Fig
43. or include the following e Delayed ignition e Too much air through the burner Delayed ignition is commonly traced to a problem with the elec trodes This condition can result from a variety of causes including the following e Improper electrode setting e Insulator cracks e A coating of soot or oil on the electrode e Incorrect pump pressure setting e Incorrect spray pattern in the nozzle e Clogged nozzle e Air shutter open too far Table 1 6 lists a number of recommended electrode settings that should eliminate delayed ignition if the electrode setting is the cause of the problem The type of nozzle spray pattern can also result in delayed ignition This is particularly true when using a hollow spray pattern in oil burners firing 2 00 gph and above It can be corrected by replacing the nozzle with one having a solid spray pattern Oil Burners 51 Table l 6 Recommended Electrode Settings Nozzle GPH A B C 45 0 75 to 4 00 Ys to Ve VY to 6 y4 60 0 75 to 4 00 Ye to 3 6 A6 to 3 1 4 70 0 75 to 4 00 Ye to 3 6 A6 to s yg 80 0 75 to 4 00 te to 3 6 A6 to 3 IA 90 0 75 to 4 00 1 to 3 6 eo to s 0 Table 1 7 lists a variety of problems encountered with oil burn ers many of which are of an internal nature and require a great degree of experience and training to correct Table l 7 Oil Burner Troubleshooting Symptom and Possible Cause Possible Remedy No heat circulator
44. pump off and burner running a Defective circulator a Replace circulator b Defective thermostat b Replace thermostat c Defective relay c Replace relay d d Replace aquastat e Incorrect aquastat setting Reset aquastat e f Loose or disconnected wiring f Tighten or reconnect wiring Defective aquastat g Defective zone valve g Replace zone valve No heat both circulator pump and burner running a Defective or loose circulator a Repair or replace coupling b Broken circulator impeller b Repair or replace circulator c Air trapped in lines c Locate point of entry and repair purge air from lines d Loose or disconnected wiring d Tighten or reconnect wiring e Defective zone valve e Replace zone valve f Frozen flow valve f Repair or replace flow valve No oil flow at nozzle a Oil level below intake line a Fill tank with oil in oil storage tank b Clogged strainer b Remove and clean strainer c Clogged filter c Replace filter element continued
45. rs can be increased by reducing the firing rate This can be accomplished by reducing the burner nozzle size but the size reduction is controlled by the minimum firing rate for the appliance Note Never reduce the nozzle size below the minimum firing rate listed on the manufacturer s rating plate As a rule it is a good idea not to reduce the nozzle more than one size if the conventional iron head burner is retained Many conventional oil furnaces and boilers are being retrofitted with flame retention head oil burners A flame retention head oil burner is designed to mix the air and fuel more efficiently than the traditional iron head units As a result the amount of excess air required for good combustion is significantly reduced resulting in a hotter and cleaner flame In these units the nozzle size can be reduced more than one size to achieve the maximum firing rate for the burner The lower limit of the firing rate of a flame retention head burner is governed by the flue gas temperature leaving the fur nace or boiler High Static Oil Burners High static oil burners are improved versions of flame retention burners They have an increased efficiency of 20 percent over flame retention burners and the high static pressure developed in these burners allows them to run at even lower excess air levels Rotary Oil Burners Rotary burners operate with low pressure gravity and are available in a number of designs depending on the differe
46. s mounted on the rim of a wheel These vanes are slanted for ward in such a manner as to provide the maximum discharge of air Figure 1 36 shows the construction of a fan and flexible coupling The operating principles of the air system are fairly simple The fan draws air into the fan housing and forces this air through the 38 Chapter Table l 4 Recommended Combustion Chamber Dimensions Square or Rectangular Combustion Chamber Nozzle Cc Round Size of L Ww H Nozzle Chamber Rating Spray Length Width Height Height Diameter gph Angle inches inches inches inches inches 0 500 65 80 8 8 11 4 9 0 759 85 60 10 8 12 4 80 9 9 13 5 10 1 004 10 45 14 7 12 4 60 11 9 13 5 80 10 10 14 6 11 1 254 35 45 15 8 11 5 60 12 10 14 6 n 80 11 11 15 7 12 1 504 65 45 16 10 12 6 60 13 11 14 7 80 12 12 15 7 13 1 752 00 45 18 11 14 6 60 15 12 15 7 80 14 13 16 8 15 2 252 50 45 18 12 14 7 el 60 17 13 15 8 i 80 15 14 16 8 16 3 00 45 20 13 15 7 60 19 14 17 8 80 18 16 18 9 17 Recommend oblong chamber for narrow sprays Courtesy of Wayne Home Equipment Co Inc draft tube and turbulator and into the combustion chamber The amount of incoming air can be regulated by adjusting the air shutter As the air is forced through these vanes it is given a swirling motion just before it strikes the oil spray This motion provides a more thor ough mixture of the oil and air re
47. s passages must be tight and free of any leaks All oil burners listed by Underwriters Laboratories Inc and Underwriters Laboratories of Canada meet the safety requirements detailed in the various booklets of the National Fire Protection Association Starting an Oil Burner Oil burner manufacturers provide detailed starting and operating instructions for their burners in their user manuals These instruc tions should be carefully followed when attempting to start an oil burner If there is no available user manual contact a local repre sentative of the manufacturer or contact the manufacturer directly for a copy The procedure for starting an oil burner may be summarized as follows Open all warm air registers Check to be sure all return air grilles are unobstructed Open the valve on the oil supply line Reset the burner primary relay Set the thermostat above the room temperature AU A wn Turn on the electric supply to the unit by setting the main electrical switch to the on position 7 Change the room thermostat setting to the desired temperature The oil burner should start after the electric power has been switched on step 6 There is no pilot to light as is the case with gas fired appliances The spark for ignition is provided automati cally on demand from the room thermostat Oil Burners 43 Note Allow the burner to operate at least 10 minutes before making any final adjustments Whenever possibl
48. sulting in better combustion Oil Burners 39 FLEXIBLE COUPLING Figure l 36 Fan and flexible coupling The shape of the turbulator varies in different models but the purpose is the same to thoroughly mix the air and oil spray Figure 1 37 shows a double turbulator consisting of an air impeller and nose piece HIGH TENSION WIRES TO TRANSFORMER NOSE RIECE AIR IMPELLER AIR CONE KsSSSSSSSS Dy rerT IIIT IIIT IL LIRTITIILITIZELIIN ITI TOTI TILT IIT I NTT alec ru as ADJUSTMENT SSS i Lo aS 4 N Pey J m G a o A n wes Lx m ELECTRODE ASSEMBLY NOZZLE Figure l 37 Details of a draft tube showing double turbulator consisting of air impeller and nose piece 40 Chapter Primary Safety Control Service The cadmium detection cell is the most effective type of primary safety control used on oil burners Malfunctions cause primary safety control to build up electrical resistance across the cell until the burner is automatically shut off As soon as the burner shuts off a reset button pops up on the burner The button must be reset pushed down to restart the burner Caution If the burner does not restart when the reset button is pushed down do NOT keep resetting the button Doing so will flood the firebox with oil If ignition does not take place the flooded firebox could result in a fire or an explosion The primary safety control can be tested by remov
49. t diagram in Figure 1 25 PRESSURE GAUGE EASY FLOW BLEED VALVE 2ND STAGE GEARS BLEED ORIFICE PRESSURE OIL RETURNED TO OPTIONAL INTERNAL REGULATING AND STRAINER CHAMBER RETURN TO SUCTION CUTOFF VALVE 7 OIL UNDER PRESSURE B OIL RETURNED TO TANK Figure l 25 Circuit diagram of a system using a two stage fuel pump Courtesy Sundstrand Hydraulics 26 Chapter Fuel Pump Capacity The capacity of an oil burner fuel pump should be sufficient to han dle the total vacuum in the system The vacuum is expressed in inches and can be determined by the following procedure e 1 inch of vacuum for each foot of lift 1 inch of vacuum for each 90 elbow in either the suction or return lines 1 inch of vacuum for each 10 feet of horizontal run inch OD line 1 inch of vacuum for each 20 feet of horizontal run 12 inch OD line After you have calculated the total vacuum you can use these data to select the most suitable pump for the burner Table 1 1 lists various vacuums and suggests appropriate pump capacities Table l I Types of Pumps Recommended for Different Vacuums Total Vacuum Type of Pump Up to a 3 inch vacuum Single stage pump 443 inch vacuum Two stage pump 14 inch vacuum or more Single stage pump for the burner and a separate lift pump with a reservoir Courtesy National Fuel Oil Institute Fuel Pump Service and Maintenance A vacuum gauge and a pressure gauge are both use
50. the provisions of the National Electrical Code ANSI NFPA 70 199 or latest edition Warning Only certified HVAC technicians or those with equivalent experi ence should attempt to install an oil burner Some sort of manual shutoff control should be provided for the oil burner in order to stop the flow of oil to the burner when the air supply is interrupted This must be placed at a safe distance from the unit and in a convenient location These manual shutoff valves generally consist of either a switch in the burner supply cir cuit for electrically driven units or a shutoff valve on the oil sup ply line 42 Chapter Primary safety controls automatic shutoff devices must be pro vided for all oil burners and oil fired units that operate automati cally without the need of an attendant on duty in other words those types of equipment found where a stationary engineer would not be employed i e noncommercial and nonindustrial locations One problem encountered when converting solid fuel heating equipment to oil use is the accumulation of potentially dangerous vapors in the ashpit of the unit This can be avoided by removing the ash door or by providing bottom ventilation to the unit This precaution is unnecessary if the ashpit also serves as a part of the combustion chamber Never install or permit the installation of an oil burner until the boiler or furnace has first been inspected and found to be in good condition The flue ga
51. uel pumps are available in a number of different sizes and designs see Figure 1 22 Single Stage Fuel Pump A single stage pump contains only one set of pumping gears see Figure 1 23 These pumps are commonly used in single pipe gravity feed installations or two pipe installations under low lift conditions with up to 10 inches of vacuum The following are the principal com ponents of a single stage fuel pump Pumping gears Cutoff valve Strainer Shaft seal Noise dampening device Shaft bearing Body Bleed valve oN aubh wn 22 Chapter PRESSURE GAUGE RETURN Vs ae ee Pa pa REGULATE a PRESSURE t INLET NOZZLE PORT i w e AIR BLEED a VE RETURN 1 4 INLET 1 4 116 BY PASS PLUG INSERT FOR 2 PIPE SYSTEM Figure 1 22 Fuel pump assembly Courtesy Sundstrand Hydraulics Fuels Used in Oil Burners No and No 2 fuel oil are both commonly used for residential heat ing purposes The No 2 is slightly more expensive but the fuel oil gives more heat per gallon used The lighter No fuel oil is used in vaporizing or pot type oil burners The No 2 fuel oil is used in both atomizing and rotary oil burners The manufacturer of the oil burner will generally stipulate the grade of fuel oil to be used If this information is unavailable the label of Underwriters Laboratories Inc and the Underwriters Laboratories of Canada will stipulate the correct grade of fue
52. ure 1 9 Oil burner with transformer removed revealing the gun assembly Courtesy Wayne Home Equipment Co Inc 10 Chapter CONNECTOR TUBE GUN ASSEMBLY OIL PUMP Figure 1 10 Gun assembly details Courtesy Lennox Industries Inc combustion process The amount of air can be manually adjusted by an air adjustment gauge located between the blower wheel and the inlet air scoop see Figure 1 7 Depending on the oil burner manufacturer a combustion air blower is also sometimes called a blower wheel a burner motor fan or an induction blower Do not confuse the combustion air blower with the furnace indoor blower The former delivers air to the oil burner for combustion The latter delivers the heated air to the rooms and spaces inside the structure Operating Principles The operation of a gun type high pressure atomizing oil burner can be traced in Figure 1 12 The fuel oil is drawn through a strainer from the supply tank by the fuel pump and is forced under pressure past the pressure relief cutoff valve via the oil line where it eventually passes through the fine mesh strainer and into the noz zle The amount of pressure required to pump the fuel oil through Oil Burners lI PRESSURE GAUGE PORT 1 3 MM H INLET PORT NOZZLE PORT SHOWN 1 6 MMI e 3 MM aN 0O Q INLET PORT BLEED PORT 14 6 MM RETURN PORT Ya
53. will depend on the requirement of the burner air pattern and combustion chamber For example 70 to 90 spray angles are recommended for round or square com bustion chambers see Figure 1 34 and 30 to 60 spray angles are recommended for long narrow chambers see Figure 1 35 Recommended combustion chamber dimensions and spray angles for nozzles are given in Table 1 4 Figure 1 33 Varieties of spray angles Courtesy Wayne Home Equipment Co Inc 36 Chapter SASS EEN 70 T0 90 COSI SOs Figure 1 34 Spray angles 70 to 90 suitable for round or square chambers Courtesy Wayne Home Equipment Co Inc Electrodes The electrodes must be frequently checked and adjusted to ensure proper and efficient ignition of the fuel oil Broken or malfunction ing electrodes can result in smoke leaking out into the rooms of the structure This problem called a puffback is not an uncommon one in oil fired appliances see sidebar Puffbacks A puffback or the leaking of sooty smoke from the combustion chamber of an oil furnace or boiler is caused by the accumulation of fuel oil in the combustion chamber of the furnace or boiler after an ignition failure When the oil burner is successfully restarted the accumulated fuel oil burns too rapidly for the exhaust system to carry away the smoke The excess smoke is forced out into the rooms through the seams in the furnace or boiler combustion cham ber walls
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