COMMON OVEN REPAIR PROBLEMS
The contemporary home is filled with a wide array of cooking appliances, and while your options are truly limitless, nearly all homes have an oven. Ovens provide the baking and broiling power you need for a wealth of delicious meals and desserts, but your oven won’t be able to complete cooking tasks if it doesn’t run properly.
There are a variety of common oven repair problems you may experience. Though you may want to solve them yourself, for the best results you should consider consulting with a professional appliance repair service. To help you diagnose any issues you may experience with your oven, we’ve compiled a list of common oven repair problems.
- Oven Does Not Heat Up
Your oven’s main function is to heat up for cooking, and any oven that does not heat up, is clearly not operating properly. This might seem like a major problem, but it could stem from some simple causes.
If you have a gas oven that does not heat, it may feature a faulty igniter. With a gas cooking range, you can check if there is an issue with the igniter by testing one of the stovetop burners. As you try to light the burner, you should hear several clicks before the gas ignites. If you notice no clicks, and your gas doesn’t ignite, you’ll want to replace your unit’s igniter. Testing an igniter in a wall oven can be more challenging, as the appliance’s igniter is located within the oven itself. This test frequently requires professional appliance repair assistance.
If you have an electric oven, you can visually check the heating elements to see if they are glowing red. If they are not glowing, they should be replaced.
- Oven Does Not Heat To The Correct Temperature
An oven that does not heat to the correct temperature will increase cooking times and result in undercooked food. This problem is typically the result of a faulty temperature sensor, which may require some simple maintenance or need to be replaced.
The temperature sensor is located within the oven to measure its heat, ensuring the appliance does not overheat. First, you should inspect the sensor and make sure it is not touching the oven wall, as this will impact its ability to measure internal temperatures correctly. If it’s not touching the wall, you can test the sensor with an ohmmeter to see if it is working properly. Be sure to consult with a professional oven technician if you’re unsure of how to do this.
There may also be a problem with your oven’s overall temperature calibration. If all your oven’s heating elements and igniters are working properly, and there appears to be no issue with the temperature sensor, you may need professional service to recalibrate the appliance.
- Oven Does Not Cook Food Evenly
Ovens are supposed to provide consistent and even heat for baking, and an oven that does not cook food evenly can be very frustrating. Like many common oven repair problems, this issue is often linked to issues with the heating elements or temperature sensor.
First, you should preheat your oven to do a visual test to see if heating elements are lit or glowing. If they function properly, test your temperature sensor. Should you notice any problems with the heating elements or sensor, they should be replaced.
If you notice no problems with your oven’s components, you may simply need to adjust the position of your oven racks, or switch to new cookware. Small adjustments to how you use your oven can transform inconsistently cooked dishes into evenly cooked masterworks. If your adjustments don’t seem to work, and your oven components appear to be functioning properly, you’ll want to consult a professional appliance repair service.
- Oven Light Does Not Work
An oven light offers added convenience that helps you check on food without opening the oven and disturbing the cooking process, and an oven light that does not work can be pretty annoying.
Most of the time, all you’ll need to do is replace your oven’s light bulb to solve this problem. But if you replace the bulb and it still does not work, your oven may have a faulty light switch, connecting wires, or electronic control system. These types of electrical problems can be difficult and dangerous to fix without the proper expertise, and it’s best to contact an appliance repairman for help.
- Oven Door Won’t Shut
You obviously want to have a properly functioning oven door. An oven door that won’t shut is a fairly common repair problem, and thankfully this one can be fixed pretty simply.
An oven door that will not shut can often be fixed by replacing its door hinges. Examine your door’s hinges to ensure they are moving properly, and if they aren’t, they should be replaced. Oven door problems can also be caused by the door springs used in some models, or the gasket that lines the inside edged of the oven door. These parts are also easy to replace, but professional oven repair services will ensure the job is done right.
- Oven Does Not Self-Clean
Almost all of today’s ovens provide a self-clean feature, saving you time when it comes to appliance maintenance and cleaning.
Problems with your oven’s self-cleaning function can stem from a variety of causes. One common cause is a problem with the door lock motor and switch assembly. During a self-cleaning cycle, the door lock switch activates the door lock motor to ensure your oven is closed throughout the cycle. An oven with a defective door lock system will not self-clean. You can inspect the oven door and motor yourself, though this is best left to a professional.
Self-cleaning problems can also be related to issues with your temperature sensor or a defective oven control board. Clock failure and wiring deficiencies are also common causes of this issue. Due to the sheer number of potential causes of self-cleaning problems, it’s ideal to consult with professional appliance technicians for solutions.
- Fallen Rack In Your Oven
There is no reason your oven racks should fall while in use, and while a fallen oven rack might seem insignificant, it can be a sign of a major problem.
The only reasons oven racks should fall is because the racks have somehow broken, or there is a problem with your oven’s interior. Over long periods of time, an oven’s interior can be damaged or warped to the point that your racks no longer fit, and fall when you move them to different levels in the oven liner. If problems with your oven’s interior are covered by your appliance warranty, a repairman can fix them.
This issue can require very extensive and expensive repairs, and if you’re not covered by a warranty it may be best to simply replace your oven. If you need to replace your oven, consider browsing this online selection of premium ovens.
Expert Oven Repair Services For The Contemporary Home
Your kitchen requires a working oven, and you should not have to deal with an oven that doesn’t function efficiently and effectively. To ensure your appliance works properly, you can have your oven serviced by a factory certified technician, who is capable of diagnosing and solving common oven problems.
For the best oven repair results, you may want to consider assistance from a professional home appliance repair service.
MICROWAVE OVEN REPAIR IN NAIROBI KENYA
Microwave Oven Repair services in Nairobi Kenya. Is your microwave oven broken? Is it not turning on? Not heating, broken glass, broken hotplate? We fix microwave ovens in Nairobi. Call us for service.
MICROWAVE OVEN MEMBRANE SWITCH
If the touch pads on your microwave oven do not respond but the display lights up, the problem is most likely with the membrane switch. This component, which is more commonly referred to as the touch pad, is actually a series of soft touch electrical switches. It is usually made up of two layers of a thin Mylar plastic with a conductive material on the inner surfaces. A formed gap between the two surfaces will separate the conductive coatings until pressure is applied by the user, making the two surfaces come in contact. When the two conductive surfaces contact each other, an electrical circuit is completed to provide an input signal to the control board. With repeated use, the conductive coating will eventually wear out and be unable to make a good enough contact to send the signal to the control board. To access the membrane switch you will need to unplug the unit and remove the cabinet. The membrane switch is often attached to the control panel and is usually connected to the electronic control board with a flat ribbon style connector. Check the connection first and if it appears okay, then you can test the membrane switch for continuity with a multi-meter. There should only be a few ohms of resistance for each touch pad when pressed. To perform this test you will require the matrix layout of the membrane switch which should be contained in the electrical schematic.
MICROWAVE OVEN CONTROL BOARD
If the touch pads on your microwave oven do not respond but the display lights up, the problem may be with the control board. The control board generates a low voltage that is supplied to the membrane switch. When a pad is depressed, the voltage signal is switched back to the control board. The control board receives these input signals from the membrane switch or touch pad and uses these commands to turn on output relays that control the various components of the microwave, such as the turntable motor and the magnetron. If the control board does not generate the low voltage signal, or if it does not sense the input signals from the membrane switch, then no output functions will occur. If you have verified that the membrane switch is fine and the connection to the control board is okay, then the control board may be defective. Replacement will require disconnecting the power and removal of the cabinet and control assembly.
MICROWAVE OVEN DRIVE MOTOR
If the turntable on your microwave is making an unusual noise, the problem may be with the drive motor. Most microwave ovens with a glass tray use a motor driven coupler to turn the tray or a roller guide. The motor is typically located below the floor of the oven, and access will need to be through the bottom. The motor is normally held in place with a retaining screw and will have two wires attached to it as well. If the motor is making a grinding noise it will need to be replaced.
MICROWAVE OVEN MAGNETRON
If your microwave is making an unusual or loud humming noise, you may have a problem with the magnetron. This component is part of the high voltage circuit and provides the microwaves that generate the heat. If the magnetron is defective, it may cause a loud humming or buzzing noise. Access to the magnetron will require removal of the cabinet. Disconnect the power and also discharge the high voltage capacitor to prevent an electrical shock. You can then locate the magnetron and disconnect the two attached wires and the mounting screws to remove it. You should also check the high voltage diode to verify that it is not shorted before condemning the magnetron.
MICROWAVE OVEN DRIVE COUPLER
If your microwave is making an unusual noise, the problem may be with the drive coupler for the turn tray. Most microwave ovens with a round glass tray use a motor driven coupler to rotate the tray on a roller guide. Some models that use a rectangular tray will have a drive coupler that has an offset center roller to drive the tray guide from side to side. For either style, remove the tray and roller guide from the oven and then inspect the coupler. Some models may require you to remove the motor from the bottom before you can pull the coupler off of the motor. The coupler normally has a D shaped opening that fits tightly onto the motor shaft. If it is cracked or worn it may become noisy and will need to be replaced. If you have to remove the bottom cover, you will need to disconnect power from the appliance first.
MICROWAVE OVEN ROLLER GUIDE
If your microwave is making an unusual noise when the turn tray is rotating, the problem may be with the roller guide under the tray. Some microwave ovens with a round glass tray use a motor driven coupler to turn the roller guide. The roller guide is used to support the tray and to engage the rotating coupler. Remove the tray and then inspect the roller guide. Check the hub to see if it engages the coupler securely and also the outer rollers for signs of cracks or damage. If there are signs of wear or damage, it should be replaced. Other models may just use the roller guide to support the tray, however the roller wheels may be damaged or worn and causing an unusual noise. If the roller guide appears to be normal, then check the coupler for damage.
MICROWAVE OVEN HIGH VOLTAGE DIODE
If your microwave is making an unusual or loud humming noise, you may have a problem with the high voltage diode. This component is part of the high voltage circuit along with the capacitor and the magnetron. Access to the diode will require removal of the cabinet. Disconnect the power and also discharge the high voltage capacitor to prevent an electrical shock. You can then locate the diode and use a multi-meter to check for continuity. Reverse the meter leads to check for continuity in the opposite direction. There should be continuity in only one direction and if not, it will have to be replaced.
MICROWAVE OVEN COOLING FAN
If your microwave is making an unusual noise, the problem may be with the cooling fan. The cooling fan is located inside the cabinet and is used to cool the magnetron. Disconnect the power and then remove the cover and locate the fan assembly. Inspect the housing for any foreign objects that may contact the fan blades and then check the
MICROWAVE OVEN DOOR INTERLOCK SWITCH
If your microwave oven doesn’t appear to shut off when the door is open, you may have a problem with the door switch. The door switches, often referred to as interlock switches, provide power to the various components of the microwave. They are designed to interrupt the power when the door is open. In certain situations when an interlock switch fails, the interior light, fan motor, or stirrer motor may continue to operate after the microwave oven door is opened. The magnetron will not operate because of a failsafe monitor switch. The interlock switches are located inside the cabinet and are activated by hooks or latches on the door. Unplug the unit and remove the cabinet. The interlock switches will have wires attached to the terminals marked common (C) and normally open (NO). You can check the switches for continuity using a multi-meter. The closed door will depress the actuator button on the switch; you should see continuity between these terminals. When the door is open there should be no continuity, and if there is the switch needs to be replaced.
MICROWAVE OVEN SMART BOARD
If your microwave oven doesn’t shut off until the door is opened, you may have a problem with the control board. The control board, sometimes referred to as the Smart Board, powers the relays that control the various functions of the microwave. If the control is defective it may not shut off a relay when the function is complete, and then opening the door to interrupt the power to the control would be the only way to terminate the cycle. If you have this symptom, the control board may be at fault. Unplug the unit and remove the cabinet. If the relays are not part of the control board, you should check the output terminals on them for continuity first. There shouldn’t be continuity when the relay is not powered. If the relays check okay, then the control board is likely defective.
MICROWAVE OVEN HIGH VOLTAGE DIODE
If your microwave oven doesn’t heat, you may have a problem with the high voltage diode or rectifier. This component helps provide the high voltage that powers the magnetron. The high voltage diode is located near the magnetron and the high voltage capacitor, so access will require removal of the cabinet. Disconnect the power and also discharge the high voltage capacitor to prevent an electrical shock. You can then test the diode for continuity with a multi-meter. Diodes are polarity specific and you should see low resistance with the meter leads in one direction and higher resistance when the meter leads are reversed. Most multi-meters will have a special setting for diodes or rectifiers. If the high voltage diode shows low resistance in both directions or shows no continuity at all, then it will need to be replaced. If you find the high voltage diode tests okay, then you will need to determine whether power is being supplied to the circuit. This is a high voltage circuit and further testing should only be performed by a qualified technician.
MICROWAVE OVEN DOOR SWITCH
If your microwave oven doesn’t heat, you may have a problem with a door switch. The door switches, often referred to as interlock switches, provide power to the various components in the microwave when the door is in a closed position, and interrupt power when the door is open. Sometimes it is possible that when an interlock switch fails, the fan motor and or stirrer motor may continue to operate but the magnetron won’t. The interlock switches are located inside the cabinet and are activated by hooks or latches on the door. Unplug the unit and remove the cabinet. The interlock switches will have wires attached to the terminals marked common (C) and normally open (NO). Check the switches for continuity using a multi-meter. With the actuator button depressed, you should see continuity between these terminals. If there is no continuity the switch will need to be replaced. You should also verify that the door hooks properly engage the switch actuator when the door is closed and adjust if necessary.
MICROWAVE OVEN MAGNETRON
If your microwave oven doesn’t heat, you may have a problem with the magnetron. This component is part of the high voltage circuit and provides the microwaves that generate the heat. If the magnetron is defective, the unit may blow a fuse, or you may still have all other functions operating normally. Access to the magnetron will require removal of the cabinet. Disconnect the power and discharge the high voltage capacitor to prevent an electrical shock. You can then locate the magnetron and disconnect the two attached wires. Attach the leads from a multi-meter to the magnetron terminals and check for continuity. There should be only 2-3 ohms of resistance between these terminals. If there is no continuity, then the magnetron will need to be replaced. Also, check for continuity between both terminals and the grounded outer case of the magnetron. If there is any continuity between either of the terminals and ground, the magnetron will need to be replaced. If the continuity checks do not reveal any defects, then live voltage tests may be required and should be referred to a qualified person.
MICROWAVE OVEN DOOR LATCH LEVER OR BUTTON
If the door on your microwave oven won’t open, you may have a problem with the door latch lever. The door latch lever assembly usually consists of a paddle or button that either pivots downward or pushes into the control panel. It then contacts the door latch assembly and releases the door hooks to allow you to open the door. If the pivot or lever portion is broken, then the door hooks cannot be lifted to release the door. Unplug the unit and remove the cover to access the door latch lever. You may also need to remove the control panel to gain better access. Remove the broken piece and insert the new part into the pivot openings. On models that use a push button style, release the retaining tabs and install the new part making sure that the return spring is installed correctly.
MICROWAVE OVEN DRIVE MOTOR
If the turntable on your microwave doesn’t rotate or is making a grinding noise, the problem may be with the drive motor. Most microwave ovens with a round glass tray use a motor driven coupler to turn the tray or a roller guide. The motor is typically located below the floor of the oven, and access will need to be through the bottom. The motor is normally held in place with a retaining screw and will have two wires attached to it as well. If the motor is making a grinding noise it will need to be replaced. If the motor doesn’t turn, you can check for voltage or continuity with a multi-meter. With the power disconnected and the bottom panel removed, locate the motor and unplug the wires to the motor. Measure for continuity at the motor terminals or at the wire harness that is still attached to the motor. If there is no continuity, the motor will need to be replaced. For voltage checks, you will need to plug the unit into a live outlet and therefore this check should only be performed by a qualified person.
MICROWAVE OVEN COUPLER
If the turntable on your microwave doesn’t rotate, the problem may be with the drive coupler. Most microwave ovens with a round glass tray use a motor driven coupler to turn the tray on a roller guide. Some models that use a rectangular tray will use a drive coupler that has an offset center roller to drive the tray guide from side to side. For either style, remove the tray and roller guide from the oven and then inspect the coupler. Most models will have a three sided coupler that will just pull off of the motor shaft. Some models may require that you remove the motor from the bottom before you can pull the coupler off of the motor. The coupler normally has a D shaped opening that fits tightly onto the motor shaft and if it is cracked or worn it will need to be replaced. If you have to remove the bottom cover, you will need to disconnect power from the appliance first.
MICROWAVE OVEN ROLLER GUIDE
If the turntable on your microwave doesn’t rotate, the problem may be with the roller guide under the tray. Some microwave ovens with a round glass tray use a motor driven coupler to turn the roller guide that the tray rests on. The roller guide is used to support the tray and to engage the rotating coupler. Remove the tray and then inspect the roller guide. Check the hub to see if it engages the coupler securely and also the outer rollers for signs of cracks or damage. If there are signs of wear or damage, it should be replaced. If the roller guide appears to be normal, then check the coupler for damage.
MICROWAVE OVEN CHARCOAL FILTER
If the exhaust fan on your over-the-range microwave is not working, the problem may simply be the charcoal filter. The charcoal filter is used to trap and absorb cooking smells when no external vent system is used. Over time, the charcoal filter will become clogged and restrict the air flow. The charcoal filter is normally located behind the exhaust air outlet grill. You can typically detach the grill by removing some retaining screws and then remove and replace the charcoal filter which may also have a spring clip to hold it in place. Replace the charcoal filter on a regular basis to maintain a good airflow. You should also check the condition of the primary grease filter as well.
MICROWAVE OVEN GREASE FILTER
If the exhaust fan on your over-the-range microwave is not working, the problem may simply be the grease filter. The grease filter or filters are used to trap cooking oils and fats to prevent contamination of the exhaust system. With normal use, the grease filters will become clogged and restrict the air flow. Normally, the grease filters are located on the bottom of the microwave and are held in place with spring clips or tabs for easy removal. Regular cleaning of the grease filters in hot water and detergent will help maintain proper airflow, however, if the filters are very dirty or damaged they should be replaced. If an external exhaust system is not used, you should also inspect the internal charcoal filter.
MICROWAVE OVEN DAMPER ASSEMBLY
If the exhaust fan on your over-the-range microwave does not appear to be working, the problem may be with the damper assembly. If you are connected to an external exhaust system, the damper is used to prevent unwanted outside air from entering the room. The damper is basically a metal or plastic flapper that closes off the exhaust duct when the fan is not running, and opens when the fan turns on. The damper may have a spring assisted flapper or it may rely on gravity to keep it closed when the fan is not in use. If the damper does not open easily or completely, then the airflow may not be sufficient to remove steam or cooking smells. The damper is located at the exhaust outlet of the microwave and removal from the wall or cabinets may be necessary. Verify that no foreign objects or the exhaust duct connector are interfering with the damper. Replace the damper if it appears to be damaged or does not open and close easily. When re-installing the vent connector, make sure there is no interference with the damper.
MICROWAVE OVEN FAN MOTOR
If the exhaust fan on your over-the-range microwave does not appear to be working, the problem may be with the fan motor. The fan motor is located at the top rear of the microwave and exhausts the air into the duct system or re-circulates into the room through the charcoal filter depending on the installation. If the fan motor does not turn on when selected, you will need to disconnect the power and remove the unit from the wall or cabinet to service. Remove the cover and locate the fan motor. Rotate the motor by hand. If the motor will not turn, it needs to be replaced. If the motor turns freely, you can check the motor for continuity with a multi-meter and if no continuity is found, you will need to replace the motor. If the motor does show continuity, the next step would be to check for power to the fan motor. This is a live voltage test and should only be performed by a qualified person. If the correct voltage is available, then the motor is likely defective. If no voltage is detected, the problem may be with the wiring or the electronic control board.
MICROWAVE OVEN DOOR SWITCH
If your microwave oven won’t start, you may have a problem with a door switch. The door switches, often referred to as primary or secondary interlock switches, provide power to the various components in the microwave when the door is in a closed position, and interrupt power when the door is open. Sometimes it is possible that when a door switch fails, the display and controls may appear normal, but the oven won’t operate. The interlock switches are located inside the cabinet and are activated by hooks or latches on the door. Unplug the unit and remove the cabinet. The interlock switches will have wires attached to the terminals that are marked common (C) and normally open (NO). You can check the switches for continuity using a multi-meter. With the actuator button depressed, you should see continuity between these terminals. If there is no continuity the switch will need to be replaced. You should also verify that the door hooks properly engage the switch actuator when the door is closed and adjust or replace it if necessary.
MICROWAVE OVEN CERAMIC FUSE
If your microwave oven won’t turn on and the display is blank, the problem may be the ceramic fuse. The ceramic fuse is used to protect the components of the microwave oven if you have a severe power fluctuation or if there is a critical fault with one of the internal components. When the fuse fails, power is interrupted to the controls of the microwave and it will become nonfunctional. The ceramic fuse is located inside of the cabinet near the entry point of the power cord. Remember to unplug the cord before attempting any repairs. You can check the fuse for continuity with a multi-meter. If the fuse failed for no apparent reason, check the major components such as the magnetron, high voltage diode, capacitor and transformer, and associated wire terminals, before changing the fuse. If the fuse failed when opening or closing the door, check for a shorted door switch, monitor switch, or improper adjustment of the door latch assembly. Use only the manufacturers’ suggested part number when replacing this fuse.
MICROWAVE OVEN THERMAL FUSE OR CUT OUT
If your microwave oven won’t turn on, you may have a problem with the thermal cut-out. Microwave ovens use one or more thermal cut-outs, sometimes called thermal fuses, to protect the oven from overheating. They are located inside of the cabinet, often near the oven cavity or the magnetron. If the thermal cut- out fails, power is interrupted to the controls or to the control outputs. Unplug the unit and remove the cabinet. Locate the thermal fuse or cut-out and remove the wires from the terminals. Check for continuity with a multi-meter and replace the part if no continuity is shown. Verify that the cooling fan is functional and that the air flow is not restricted.
MICROWAVE OVEN DOOR LATCH ASSEMBLY
If your microwave oven won’t turn on, you may have a problem with the door latch assembly. The door latch assembly usually consists of two hooks that protrude from the door and fit into the door switch holder that is mounted to the frame of the microwave. The hooks will contact the door switches to provide power to the controls and also, latch onto the holder to keep the door closed. The latch assembly is normally made of plastic and usually has a spring attached to provide downward tension to keep the hooks engaged. If either of the hooks is broken or does not have any spring tension, the switches may not be engaged. If this happens, the oven won’t turn on and you may need to replace the assembly. Unplug the unit and remove the inner door panel to access the door latch. The inner panel is normally attached by plastic tangs and caution should be used to remove it.
MICROWAVE OVEN DOOR LATCH ASSEMBLY
If the door on your microwave oven doesn’t appear to close properly, you may have a problem with the door latch assembly. The door latch assembly usually consists of two hooks that protrude from the door and fit into the door switch holder that is mounted onto the frame of the microwave. The hooks will contact the door switches to provide power to the controls and also latch onto the holder to keep the door closed. The latch assembly is normally made of plastic and usually has a spring attached to provide downward tension to keep the hooks engaged. If either of the hooks is broken or does not have any spring tension, you may need to replace the assembly. Unplug the unit and remove the inner door panel to access the door latch. The inner panel is normally attached by plastic tangs and caution should be used to remove it.
MICROWAVE OVEN TORSION SPRINGS
If the door on your microwave oven doesn’t appear to close properly, you may have a broken torsion spring. On microwaves that have a door that opens downward, torsion springs are used to keep it closed. There are normally a left and right side spring and they are often different sizes. If your door won’t stay closed, one of the springs may have broken. Unplug the unit and remove the inner and outer door panels to access the torsion springs that are located at the bottom front of the door. Depending on the model involved, the panels may be held in place with screws from the inside, bottom, or sides. Use caution as the outer glass door may be heavy.
OVEN MAINTENANCE SERVICES IN NAIROBI AND NAIROBI KENYA
We offer oven Maintenance services for customers in and around Nairobi, Nairobi County Area, Machakos, Kiambu, Thika, Ngong, Kajiado, Limuru Athi River, Syokimau, Langata, Kitengela, Embakasi, Karen, Loresho, Lavington, Kileleshwa, Spring Valley, Kiuna, Thoome, Muthaiga, Runda, Gigiri, Nyari, Ruaka,
What is Oven Maintenance?
Oven maintenance refers to all the procedures and activities (covered by a program for plant maintenance) carried out to preserve the initial operating conditions (mechanical, thermal, and electrical) of an oven and and its parts.
Oven maintenance activities should focus on the following aspects:
Scheduled inspection of the oven’s overall status
Replacement of loose/flaking, worn, rusty, damaged, or broken components (e.g., nuts, screws, bolts, screw threads, taper pins/fasteners)
Regular lubrication of moving parts and/or metal-to metal contacts (drives, motors, bearings, chains)
Repair and welding of equipment subject to stress and load
Oven maintenance is essential to guarantee its ideal conditions of operation and conservation. A properly maintained oven:
Offers a longer service life to the baker
Guarantees maximum equipment availability
Works efficiently in terms of fuel consumption to directly bake the products
Generates minimum heat losses (e.g., through the humid air extraction system and wall insulation)
Ensures steady state conditions during baking, hence producing consistent quality
Prevents breakdowns, idling, and rework
Minimizes explosion risks (e.g., in the case of direct gas-fired ovens)
Reduces downtime and prevents total plant shutdowns that directly affect production, order deliveries, and sales
Relevance
Oven maintenance is a key component of the whole plant maintenance program. Members of staff (e.g., in purchasing, maintenance, quality, and operations departments) should pay special attention to the oven because it:
Imparts final and definite characteristics to the products
Is the equipment with the longest cycle time in the production line
Is the processing unit that consumes the majority of the energy (fuel and electricity) used by the plant
Is the machine with the highest acquisition costs (lease/rental prices, depreciation and amortisation costs, value of asset, commissioning, and setup charges)
Greatly affects the total manufacturing costs of a bakery, according to its energy efficiency
Broken and/or malfunctioning ovens can bring bread-making plants to a standstill. Medium-sized and retail bakeries usually operate under the “we fix it” approach, in which the maintenance department performs all maintenance activities and interventions. These activities are “firefighting” maintenance that occurs when one of the ovens, mixers, or proofers in the processing line breaks down.
In the traditional bakery, the production department works under the “we operate the oven and run it until it breaks” mentality. Oven operators generally do not perform any maintenance activities. Instead, the operators contact the maintenance department when the oven breaks down. In addition, the operators are inactive during the maintenance activities.1
When the production line is operating smoothly, a down or broken piece of equipment impacts all preceding steps (i.e., mixing of ingredients, dough make-up operations, and proofing), thus increasing the risk of product contamination and deterioration.
This is why bakeries should migrate to a proactive maintenance approach for ovens, which covers:
Preventive maintenance: Planned sequence of inspections, interventions, and repairs designed to avoid equipment failure.
Corrective maintenance: Scheduled interventions or works for malfunctioning or broken equipment in order to restore it to proper working condition.
Unscheduled maintenance: Reactive interventions or works immediately performed when a critical repair and/or replacement is needed, often during unpredicted breakdowns.
Temporary repairs: Quick repairs that use a variety of approved temporary materials (e.g., tape, wire, strings, cardboard, plastic) and that are replaced with permanent repairs as soon as possible.2
How it works
In order to execute and sustain oven maintenance activities, bakeries require management guidelines, operating procedures, safety instructions, oven maintenance manuals from the manufacturer, trained and educated personnel, documentation, and recordkeeping.
The following equipment parts and conditions should be taken into account in the oven maintenance subprogram:
- Welded metal components
- Driving chains and belts
- Motors and drives
- Steam lines and fittings
- Air lines and fittings
- Seals and gaskets
- Fans/blowers
- Fan filters
- Explosion door arrangement
- Oven flues
- Bearings
- Conveyor belts/bands
- Oven band tension
- Automatic tracking rollers
- Temperature controllers
- Sensors
- Motors and electrical control equipment
- Dampers
- Burners and gas equipment
Oven maintenance checklist
Different types of ovens require special attention. A preventive oven maintenance subprogram, including adherence to the manufacturers’ recommendations, should be established and followed. This program should set a minimum maintenance schedule that includes inspection and work interventions. An adequate supply of spare parts should be maintained, and inoperable equipment should be cleaned, repaired, or replaced, as required.
Visual operational checklist
- Burners, for ignition and combustion characteristics
- Air–fuel ratios
- Baking temperatures
- Operation of ventilating equipment/air extraction fans or blowers
- Regular shift checklist (checks performed at the start of every shift)
Check the set point of control instrumentation (e.g., temperature, heat flux, humidity of baking chamber, and air flow for convective drying mechanisms).
Check positions of hand valves, manual dampers, secondary air openings, and adjustable bypasses.
Check blowers, fans, compressors, and pumps for unusual bearing noise and shaft vibration; check belt tension and belt fatigue of V-belt-driven equipment.
Perform lubrication in accordance with manufacturer’s requirements.
Periodic checklist (maintenance activities performed at intervals based on the recommendations of the manufacturer and the requirements of the process)
- Inspect flame-sensing devices for condition, location, and cleanliness.
- Inspect thermocouples and loose connections.
- Check setting and operation of low and high temperature limit devices.
- Check igniters and verify proper gap.
- Check control valves, dampers, and actuators for free, smooth action and adjustment.
- Test fuel manual valves for operation and tightness of closure as specified by the manufacturer.
- Test instruments for proper response to sensors failure.
- Clean or replace the air blower filters.
- Clean the water, fuel, gas compressor, and pump strainers.
- Inspect burners for proper operation, air–fuel ratio, plugging, or deterioration.
- Check all orifice plates, air–gas mixers, flow indicators, meters, gauges, and pressure indicators; if necessary, clean or repair them.
- Test pressure relief valves; if necessary, repair or replace.
- Inspect air, water, fuel, and impulse piping for leaks.
- Inspect radiant tubes and heat exchanger tubes for leakage, and repair if necessary.
- Lubricate the instrumentation, valve motors, valves, blowers, compressors, pumps, and other components.
- Test and recalibrate instrumentation in accordance with manufacturer’s recommendations.
- Test flame safeguard units.
