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Home , Boiler, Furnace

Maintaining Conventional Residential Oil-Fired Heating Systems

Greg Tuttle, Graduate Student, Department of Agricultural Engineering Susan Mireley, Associate Professor and Extension Housing Specialist Department of Human Environment and Design

Periodically, oil-fired heating exchanger; a distribution systems need adjustment to keep system (ducts in the case of forced them running in the safest, most air systems, pipes in hot efficient and least costly manner. systems); a burner by-products This publication covers maintenance This publication is designed to help of conventional oil-fired heating elimination system (exhaust stack, systems only Information on you understand how oil-fired maintenance and repair of the or ); and control newer oil is not covered. heating systems work (both forced mechanisms (such as the air and hot water systems), what and master switch). Understanding periodic preventive maintenance how these various parts operate and tasks the units should have, and work together is an important part of what special tasks and problems any preventive maintenance might arise that would need the program. attention of a heating contractor.

All oil-fired heating systems are composed of a heat producing source (a in the case of forced air systems and a for hot water systems)

2 HOW AN OIL-FIRED WORKS

How the Typical control, the furnace blower begins and finally the baseboard units (i.e., Oil Burner Works pulling cool air through the radiators or convectors in some When a room thermostat is return air registers and ducts (see systems) in the various (see turned up or the Figs. 1 and 3). The air is passed Fig. 4). As cool room air passes drops below the thermostat setting, through a filter to clean it of dust. over the warmed baseboard unit the unit signals the furnace or It then passes through the heat surfaces, the air absorbs heat and boiler that additional heat is exchanger, as described above, distributes it throughout the room. needed. As a result of the signal, where it is warmed by the hot Individuals, furnishings and objects the burner motor activates the gases passing through near the baseboard units are also oil , sending to a the on their way warmed by heat given off by the nozzle at the end of an air tube out of the . The furnace units. The now cool water (see Figs. 1 and 2). Under high blower then forces the warm completes the cycle, flowing from pressure, the fuel oil is pushed supply air into a plenum and the baseboard units through the through the nozzle to form a fine through the supply ducts, finally return branches and the return mist. At the same time, the burner distributing it through supply main back to the boiler. blower, also operated by the registers in each room in the . When the water in the boiler burner motor, blows room air into The two air supplies, the drops below a predetermined the same air tube. The two-the air combustion air and the air temperature, the activates and the fuel oil mist-combine to distributed through the house the burner (see Fig. 2). The heat form a highly flammable vapor that system, should never come in given off by the burner warms the is then ignited by a spark supplied direct contact with each other. heat exchanger and rewarms the by the ignition electrodes. Once water in the boiler, which holds it in started, the flames continue to burn How a Hot Water Distribution reserve until the circulator pump in the with System Works moves the water through the additional fuel oil and room air When a house thermostat calls distribution system once again. supplied through the air tube/ for heat from a hot water This two-phase process enables nozzle. In turn, the combustion distribution system, the circulator the system to maintain an on- gases from the flame flow through pump is activated (see Fig. 2) and demand supply of hot water at all the flue passageways of the heat supplies hot water held in reserve times. The homeowner does not exchanger, heating it, and then in the boiler throughout the have to wait for the water to be continue to flow up and out the distribution system-through the reheated and circulated through the exhaust stack (see Fig. 1 for a supply main, the supply branches system. forced air distribution system and Fig. 2 for a hot water distribution MAINTENANCE AND INSPECTION system). In the meantime, heat is YOU CAN DO transferred from the flue gases through the heat exchanger During the heating season, heating system operating to the heat distribution medium furnaces and can efficiently and safely. You can do (either air or water) that flows accumulate a build-up of dirt. a number of the maintenance through the supply system, In addition, the various moving and inspection tasks yourself. distributing heat to various parts of parts wear. Dirt and wear can You may want to ask your heating the home. lead to a loss of system efficiency, contractor to show you some of system failures, and health and the procedures during his or her How a Typical Forced Air safety problems. Annual next visit or consult your heating Distribution System Works inspections and maintenance system owner’s manual. It should When the air temperature in the are required to keep an oil-fired provide an excellent guide to the heat exchanger reaches a predetermined temperature, which is controlled by a -and-limit 3 types of activities do-it-yourselfers manufacturer’s name and probably the correct owner's manual can be can do. This publication describes the address on the nameplate sent to you. Both numbers can be some of those activities in a affixed to your unit somewhere. If found on the unit's nameplate. general way, but the owner's the manufacturer's address is not If you are a novice do-it manual will give you specifics for available, consult your heating yourselfer, follow the your system. contractor or search the Yellow manufacturer's recommendations If the owner's manual is not Pages to find the name of a carefully, and do only those tasks available, write to the heating contractor that sells the explained in the manual. All others manufacturer and request that one brand you own. In your letter, give should be done by a heating be sent to you. You will find the the model and serial number of contractor. Oil is an efficient your unit so

4 and safe fuel if the equipment burner motor. Vacuum away any connections, bare wires, blown burning it is well maintained by loose dust and wipe away any oil fuses, tripped circuit breakers and knowledgeable people. Novices buildup or greasy dirt. Lubricate tripped reset buttons (the reset and inexperienced tinkerers should the burner motor according to your button automatically disconnects be aware of the potential for owner's manual. the to an overloaded creating problems. 3. Inspect the burner mounting electrical motor) indicate that an plate for evidence of leaks (see electrical problem is present. The Furnace/Boiler Fig. 1). They can alter the fuel/air Contact your heating C-6ntractor 1. Change the fuel oil filter mixture and allow smoke to to correct it. (Warning: electricity periodically (see Figs. 1 and 5). escape into the room. If smudges is potentially dangerous for people The fuel filter cleans the fuel of are present around the plate, call not familiar with its operation. any impurities (e.g., dirt and water) your heating contractor to correct Repairs should be made by a that may affect the efficient supply, the situation. qualified service person.) ignition and burning of the fuel. 4. Inspect the furnace's/ boiler's 5. Inspect the exhaust stack for Consult the owner's manual for the electrical system (i.e., master bad connections and damaged or correct procedure. switch and electrical cable, see corroded pipes (see Figs. 1 and 2). 2. Clean and lubricate the burner Fig. 1). Electrical problems affect Replace if damage is evident. motor (see Fig. 1). Dust and oil the performance of a unit and also 6. Clean the draft regulator, buildup will shorten the life of the present a safety hazard. Bad the mechanism controlling the rate controls are found on older units, failure. Replace the belt when at which combustion gases are while primary controls are found slippage can no longer be pulled up and out the exhaust stack on newer ones. If the reset button corrected or belt failure seems (see Figs. 1 and 2). Soot and dust trips the burner off, a fuel supply likely. Adjust the belt tension buildup can interfere with the draft or ignition problem has occurred. according to your furnace's regulator's efficient operation. Push the reset button once to owner's manual. (Note: many Vacuum any loose dust and wipe restart the burner. If the reset newer oil furnaces do not have a off any greasy soot. Also clean the button trips the burner off again, fan belt-a motor drives the fan back side of the hinged plate. Any contact your heating contractor. directly.) Warning: shut off modifications or changes in the 13. Safety note: oil-fired furnaces electricity to the unit before draft regulator setting should be and boilers require an adequate starting belt adjustment. done by a qualified service person. supply of air to ensure proper and 3. Replace the 7. Inspect the fuel storage tank safe burning of the fuel. In periodically to ensure that air is for leaks. Clues include oil stains or addition, adequate clearances are circulating freely and cleanly (see puddles and/or a strong odor in the necessary between combustibles Fig. 1). Dirty air filters slow air vicinity of the tank. Call a heating such as walls, and framing movement, make other furnace contractor to replace the unit. members and the furnace/boiler, components work harder (which 8. Clean the furnace room the vent stack and the chimney shortens their useful life), and periodically. Dirt and lint from Never enclose a unit unless you waste energy. Inspect them areas surrounding the unit can be check with a heating contractor monthly initially to determine how pulled into the burner along with about the unit's combustion air often they should be changed. combustion air. Eventually they will needs. Never store combustible Follow directions provided in the slow the movement of combustion materials near the unit. furnace owner's manual. air to the unit, causing it to burn 4. Inspect work for air leaks inefficiently and give off soot. Forced Air Distribution System that result in heat loss and wasted 9. Clean and adjust the room 1. Clean the blower fan and the money (see Fig. 3). While the fan . Dust buildup interferes blower housing and clean and is operating, locate them by with efficient thermostat operation. lubricate the blower fan shaft and running your hand over areas Remove the cover and wipe away the blower motor (see Fig. 1). where you suspect leaks. Seal dust with a soft brush, such as a Dust, dirt and debris buildup leaks with duct tape. watercolor paint brush. Work affects the efficient operation and 5. Clean and clear the room carefully- thermostats are fragile. useful life of these components. supply and return air registers of 10. Observe the color of smoke Remove it with a vacuum or soft any dust or obstructions (see Fig. leaving the chimney. Black smoke cloth and lubricate according to 3). They reduce air circulation and is a sign of poor combustion. Call a your owner's manual. (Note: some waste energy dollars. A vacuum heating contractor to make needed newer units may not require will do a good job. adjustments. lubrication because the bearings 6. Any warning signs noted 11. Inspect any visible sections of are sealed.) Warning: shut off during the heating season such as the chimney and the chimney top. electricity to the unit before unusual odors from the registers, If they are worn or damaged, starting these procedures. discoloration over registers, consult your heating contractor. 2. Inspect the blower fan belt for excessive dirt in the house air 12. Most oil furnaces are wear and correct tension (see Fig. supply, or unusual cycling of the equipped with a reset button 1). It is fairly common for the belt burner or fan or both should be located on either the stack control to be too tight, which can lead to reported to your heating or the primary control-the safety premature failure of the motor or contractor. devices that shut the burner off if fan bearings and possible belt 7. Periodically throughout the a flameless condition exists. Stack breakage. On the other hand, a heating season, make a conscious loose belt can slip, causing faster effort to listen to your unit as it belt wear and premature belt goes through a heating cycle. The 6 normal procedure is: the room thermostat calls for heat, pump (see Fig. 2). Dust and dirt systems contain automatic bleeders the burner goes on, the fan then buildup inhibit efficient operation. and do not require this step. starts. Both should remain on until Consult your owner's manual for Consult and follow your owner's the thermostat temperature is instructions and lubrication needs. manual for the correct satisfied. Once it is satisfied, the 2. Clean and bleed baseboard procedures.) burner stops first, followed by the units (convectors or radiators in 3. Inspect baseboard units to fan. If the burner or the fan or both some systems; see Fig. 4). Both ensure that adequate clearance cycle on and off frequently before dust and dirt buildup on the exists between them and the , the thermostat is satisfied, a baseboard unit's fins and air in the particularly carpeted . problem exists. Consult your pipes decrease the Clearance is necessary to allow air heating contractor. Likewise, if the efficiency of the baseboard unit. A to flow freely around the unit. If burner ever goes on but the fan vacuum and a softbristle brush your hand cannot slip easily into does not follow, call a heating work well together for cleaning the this area, consult a heating contractor. fins. If air is present in the pipes, contractor about raising the unit. you'll hear a sound similar to water Hot Water trickling. Bleed the unit by opening Distribution System the air until water runs freely 1. Clean the circulator motor and from the unit. Then close the valve. lubricate the motor and circulator (Note: many modern hot water MAINTENANCE AND INSPECTION A SERVICE PERSON SHOULD DO

Though you can do the maintenance and repair tasks described in your owner's manual, other jobs require the knowledge of a heating contractor. Inexperienced homeowners attempting these tasks may make mistakes that expose them and their families to unnecessary hazards and possibly damage the equipment. We mention these tasks because a heating contractor should do them during a regular maintenance visit. When selecting a contractor, ask about the standard service procedures followed and see if they are similar to those described here. We 4. Inspect, clean and adjust the flameless condition, the stack suggest that a heating contractor ignition electrodes (see Fig. 1). If control will shut down the burner. service your system every year. ignition does not occur because of It needs to be functioning well at The cost will be approximately $50 a problem with the electrodes and all times. (Newer units do not have per visit. the fuel/air mixture continues to be a stack control. They have, instead, pumped into the combustion a solid state primary control, which The Furnace/Boiler chamber, an explosive condition incorporates a cad cell, a light- 1. Clean or replace the burner will exist, an obvious safety hazard. sensitive mechanism that monitors nozzle (see Fig. 1). With use, the 5. Inspect and clean the electricity to the burner, shutting burner nozzle passage ways may transformer (see Figs. 1 and 2). the burner down if a flame is not become partially blocked or The transformer amplifies the produced. The cad cell should be enlarged. In either case, the electrical voltage supply (from 110 inspected for dirt and soot amount of fuel oil being delivered to 120 volts to 5,000 to 10,000 accumulation and cleaned as to the combustion chamber will not volts) to the electrodes, initiating needed. It should also be be correct and the resulting fuel/air the spark that starts combustion. realligned.) mixture will contain either too 6. Adjust the air volume control 9. Adjust the draft regulator (see much or too little fuel. Both (see Figs. 1 and 2). This Figs. 1 and 2). Improper conditions will lower the efficiency mechanism controls the amount of adjustment can result in excessive of the furnace or boiler. air in the fuel/air mixture, a major heat loss up the flue. 2. Clean the burner blower (see factor affecting burner efficiency. 10. Clean the heat exchanger Fig. 1). Dirt buildup on the blower 7. Inspect and adjust the fuel oil surfaces (see Figs. 1 and 2). causes an improper air/oil mixture pump, which regulates the amount Cleaning improves heat transfer by cutting down on the amount of and the pressure of fuel oil in the between the heat exchanger and air supplied to the unit and lowers fuel/air mixture (see Figs. 1 and 2). the heating medium (the air or the efficiency of the burner. Improper calibration of the fuel oil water supply). 3. Adjust the burner flame (see pump decreases furnace or boiler Figs. 1 and 2). An improper burner efficiency. flame level will generate less heat 8. Inspect, adjust and clean per unit of fuel than the proper stack control, a necessary safety flame could produce. device (see Figs. 1 and 2). If the furnace or boiler is operating in a 11. Check for combustion leaks. Combustion leaks allow dangerous gases to escape into the furnace room. 12. Perform efficiency tests and make required adjustments. Efficiency tests help the contractor determine burner efficiency and overall furnace or boiler efficiency and point to specific areas where adjustments can be made to increase efficiency. These tests are essential to ensure that your oil furnace or boiler is running at its peak level of performance. Because of their importance, the tests are described and explained in more detail on pages 14-15. the heat exchanger becomes too Hot Water Forced Air hot. It is never adjusted or Distribution System Distribution System changed-the other two can be, 1. Check the circulator pump 1. Align the blower pulley and however, For example, the fan-on coupler for wear and broken the blower motor (see Fig. 1). temperature is usually about 135 coupler springs (see Fig. 2). The Improper alignment can cause degrees F. When the air around coupler connects the motor with abnormal belt wear and slippage. the heat exchanger reaches this the pump. Normally, if the coupler (Note: most newer oil furnaces do temperature, the blower fan comes springs are broken, a loud racket not have pulleys a motor drives the on and moves the heated air occurs; they have been known to fan directly.) throughout the home. The fan-off be broken, however, with little 2. Adjust the blower fan speed temperature is usually set at noise. (see Fig. 1). Excessive fan speed approximately 100 degrees F. 2. Check the operation of all will cause duct noise and waste When the air surrounding the heat safety controls (see Fig. 2), such as electricity. If the fan is set exchanger reaches this the safety , which would unnecessarily low, an excessive temperature, the fan blower stops relieve the system if overly high amount of heat will be lost through so it doesn't circulate cool air pressure should occur because of the supply ducts before it reaches through the home and cause overheating. the registers to provide room heat. uncomfortable drafts. To save 3. Check and adjust air and water 3. Adjust and test the fan-and- energy, you may want to ask your levels in the , which limit control, which measures the heating contractor to lower these provides a reservoir for the safe temperature of the air surrounding two temperature settings to a level collection of water as it expands the heat exchanger. It closer to the house thermostat during the heating cycle (see Fig. automatically turns the furnace setting. As a result, the furnace 2). Note: many new expansion blower on and off during each will supply more heat to the house tanks contain bladder or diaphragm burning cycle and shuts the burner BUT the air will feel cooler. You devices that control water and air down if the heat exchanger may experience some draftiness levels automatically. becomes overly hot. The control and discomfort after the changes monitors three temperatures: a until you become accustomed to fan-on temperature, a fan-off the new settings. temperature and a temperature limit, which is a safety device designed to shut the burner off if

OIL FURNACE OR BOILER EFFICIENCY TESTS

Efficiency tests are the best means relatively expensive. Four tests thermometer. available to determine if your oil should be conducted to ensure that Two steps have to be taken furnace or boiler is functioning at a furnace achieves maximum before conducting the tests. First, a its maximum efficiency level and efficiency. hole must be drilled in the flue pipe thus providing you with the most Efficiency tests are a series of close to the body of the heating output for your energy measurements: a draft furnace/boiler and ahead of the dollars. Efficiency tests indicate volume measurement, a smoke draft regulator. This hole will be the amount of heat output you are test, a carbon dioxide (C02) used to insert the test equipment receiving in relation to fuel input percentage reading and a flue gas and provide readings. After the into the system. temperature reading. The first two tests are completed, it can be Efficiency tests should be done tests are done to make burner replugged with a sheet metal by a heating contractor because adjustments, and the others provide screw. Second, immediately before performing them and making a measure of the overall efficiency testing, the furnace or boiler must necessary adjustments requires of the system. The equipment be brought up to its normal specialized knowledge. In addition, required for these tests includes a operating temperature. This can be the equipment needed to perform draft gauge, a smoke tester, C02 accomplished by turning the house them is specialized and indicator and a flue gas thermostat above its normal reading for 10 to 15 minutes. The tests are then conducted. The first test conducted measures the amount of draft or the speed of the movement of combustion gases up the chimney. The test indicates how forcefully the gases are being moved out of the house. The test probe of the draft gauge is inserted into the flue pipe hole and the reading recorded. A high draft reading indicates that the hot gases are being drawn up the flue too quickly and excessive heat is being wasted through the chimney. A low draft reading, on the other hand, indicates the gases are not being vented quickly enough. To correct draft problems, the heating contractor will adjust air intake to the burner and combustion chamber and the balance weight on the draft regulator .

14 The second test is a smoke test, excessive amount of heat is indicates furnace efficiency. An which indicates the soot content of escaping up the chimney, thus efficiency percentage below 75 the flue gases. The probe for the wasting energy dollars. Low percent indicates that the flue gas smoke tester is inserted into the temperatures, on the other hand, temperature is too high and the flue pipe hole and a specified such as 300 to 350 degrees F. or percent C02 in the flue gas is too amount of smoke is drawn through lower, indicate that corrosive low. filter paper. The darkened filter may be occurring in We strongly urge that you have a paper is then compared to a smoke the chimney. The contractor will heating contractor perform the test scale (ranging from 0 to 10) correct either situation. efficiency tests annually. The cost supplied with the test kit. Anything The results of the C02 and flue of hiring a contractor varies, but on higher than 2 on the scale means gas temperature tests are applied the average, it runs approximately the air/fuel mix is poor and an to a chart similar to the one shown $50 for a regular maintenance excessive amount of unburned fuel in Fig. 7, which provides an visit. The contractor should be able is escaping up the chimney. The indication of furnace or boiler to estimate the time needed and heating contractor will adjust the efficiency. The C02 percentage thus the additional cost for air supply to the burner to achieve reading is located along the conducting the tests. The potential a more smokeless flame. horizontal line of the graph and the savings on your annual heating bill Measuring and adjusting the flue gas temperature is located from the adjustments could very furnace or boiler's draft and along the vertical line. The point well pay for the call and perhaps achieving a low smoke test number inside the graph where lines from save some extra dollars as well. set the stage for accurate C02 and these plotted points intersect stack temperature tests. These final two tests are used to calculate the operating efficiency of the unit.

The contractor measures the C02 content of the flue gas to determine if excess air is present in the flue. It is accomplished by inserting the C02 indicator probe into the flue pipe hole and extracting a specified amount of flue gas. The reading should register somewhere between 0 and 14 percent. If the percentage of

C02 is low (less than 8 percent, for example), the air/fuel mix is high in excess air, and valuable heat is being wasted out the flue or chimney. The heating contractor should adjust the air/fuel mixture. Finally, the flue gas temperature is taken to determine the unit's ability to utilize heat and not waste it. It is measured by inserting the flue gas thermometer into the flue pipe hole. A high flue gas temperature, such as 500 to 550 degrees F or over, indicates an

15 Sources:

Brotherson, Donald, Heating the Home, G3.1. Small Council- Research Council, University of Illinois, 1976.

Energy, Mines and Resources Canada. The Billpayer's Guide to Heating Systems. Minister of Supply and Services Canada, 1983.

Knight, Paul A. Mechanical Systems Retrofit Manual: A Guide for Residential Design. New York: VanNostrand Reinhold Company, 1987.

Mireley, Susan and Don D. Jones, The Indiana Do It Yourself Home Maintenance Checklists: Space Conditioning Systems, HE-63. Indiana Cooperative Extension Service, Purdue University, July 1986.

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