Ideal Fuel Pressure For Oil Burner Furnace Operations

Oil burner nozzles are used to atomize fuel oil and allow it to burn. Atomization refers to the process of raising the pressure of the fuel and forcing it through the nozzle, resulting in a fine spray. The fuel pressure in an oil burner furnace is typically set at 100 psi, although some burners may require higher pressures of up to 140 psi or more. Adjusting the fuel pressure can affect the atomization of the oil, with higher pressures resulting in a finer spray and improved burner efficiency. It is important to note that changing the fuel pressure may require adjustments to the nozzle size to maintain the desired fuel flow rate. Improper adjustments to the fuel pressure and nozzle size can lead to incomplete combustion, increased fuel consumption, or even damage to the boiler. Therefore, it is recommended to consult a qualified technician or refer to the manufacturer's specifications before making any adjustments to the fuel pressure or other settings in an oil burner furnace.

Fuel pump pressure and nozzle size

The fuel pump pressure and nozzle size are critical components of an oil burner furnace. The fuel pump pressurises the oil, forcing it through the nozzle, where it is atomised into a fine spray. This process is essential for the efficient combustion of the oil.

Fuel Pump Pressure

The fuel pump pressure can vary depending on the specific oil burner furnace model and manufacturer. However, most residential-style oil burners operate at a pressure of 100 psi. It is important to refer to the manufacturer's specifications to determine the correct fuel pump pressure for your particular furnace. Adjusting the fuel pump pressure can affect the atomisation of the oil and, consequently, the combustion efficiency of the furnace.

Nozzle Size

The nozzle size is another critical factor in the combustion process. The nozzle is typically rated in gallons per hour (GPH) at a specific pump pressure, usually 100 psi. For example, a 0.85 gph nozzle will deliver 0.85 gallons of oil per hour at a pump pressure of 100 psi. The nozzle size can be adjusted to regulate the fuel flow rate, allowing for fine-tuning of the furnace's heat output.

Relationship Between Fuel Pump Pressure and Nozzle Size

The fuel pump pressure and nozzle size are interdependent. Increasing the fuel pump pressure can compensate for a smaller nozzle size, maintaining the desired fuel flow rate. For instance, if a 1 gph nozzle is used at a pump pressure of 120 psi, the actual fuel flow rate will be approximately 1.10 gph. This adjustment can be useful when a specific nozzle size is required to fit the shape and size of the combustion chamber.

Nozzle Spray Pattern

In addition to the metering rate, the nozzle spray pattern also plays a crucial role in efficient combustion. The spray pattern is characterised by the spray angle and spray type. The spray angle refers to the angle at which the spray emerges from the nozzle, with smaller angles resulting in narrower spray patterns. The spray type, indicated by a letter stamped on the nozzle, determines the distribution of droplets within the spray pattern. Common spray types include solid (B), hollow (A), and semi-solid (W).

Maintenance and Replacement

Periodic replacement of the nozzle is necessary for the clean and reliable operation of the oil burner furnace. Nozzles can become clogged with debris or eroded due to friction with the oil, requiring replacement. It is essential to refer to the manufacturer's specifications and seek professional assistance when adjusting the fuel pump pressure or replacing the nozzle to ensure the continued safe and efficient operation of the oil burner furnace.

Oil burner maintenance

Step 1: Turn off the furnace

Before beginning any maintenance on your oil burner, it is important to first turn off the furnace to protect yourself and your home. This involves switching off the electrical power and fuel supply. The electrical power switch is usually located near the burner or at the top of the cellar stairs and is often marked with a bright red plate. The fuel shutoff valve can be found near the oil tank or on the incoming gas pipe.

Step 2: Remove carbon soot and other debris

The combustion chamber plays a key role in the furnace's performance, so it is important to keep it clean. Use a small wire brush and/or an industrial shop vacuum to remove carbon soot, carbon dioxide, water vapour, and other debris from the chamber. Check for any cracks or holes in the chamber, as this may require you to replace it.

Step 3: Evaluate the flue pipe

The flue system ensures that the furnace's combustion products exit your home properly. Check the flue pipe for any cracks, holes, or leaks, especially where the pipe meets the furnace. Minor holes can be patched with foil tape, but larger holes may require a replacement.

Step 4: Replace the oil filter

The oil filter should be replaced at least twice per heating season as it stops small impurities from clogging the oil burner nozzle, which can cause the furnace to misfire and shut down. The oil filter is usually located close to the furnace and can be replaced in a few minutes.

Step 5: Replace the air filter

The air filter should be replaced every one to three months, depending on the size of your home, whether there are pets or smokers, and your furnace model. First, purchase the correct air filter for your furnace and locate the existing filter, which is usually inside the furnace or inside the furnace's return air vent. Look for an arrow that indicates the airflow direction, which will show you how to install the new filter.

Step 6: Adjust the burner and test its efficiency

To test the burner's efficiency, a combustion analysis is required. This involves measuring the flue gas concentrations and temperature, the draft pressure, and the soot level. A combustion analyser is used to collect these measurements and can be purchased or rented.

Step 7: Clean the floor vents

Vacuum the floor vents and remove any dirt, dust, pet hair, or other debris to ensure consistent furnace performance and maintain air quality.

Additional Maintenance Tips:

• Nozzle: The burner nozzle should be replaced regularly as it can become clogged with debris or worn down over time.
• Fuel pressure: Check that the fuel pressure is correct for your furnace. This can be adjusted with an adjustable pressure relief valve.
• Filter: Replace the filter located at the air handler.
• Heat exchanger: Keep the heat exchanger vacuumed out and clean to ensure your oil furnace has a long lifespan.
• Annual maintenance: Schedule annual maintenance visits from a professional technician to ensure your furnace is running smoothly.

Safety Considerations:

• Oil burners can be dangerous if you are untrained, so it is important to consult a professional if you are unsure about any maintenance tasks.
• When working with a gas furnace, ensure that the entire power system and any connected circuits are inactive.
• If you discover a gas leak, contact a furnace professional immediately.

Oil burner safety mechanisms

Oil burners are fitted with safety mechanisms to ensure proper ignition and prevent accidents and injuries. Here are some essential safety measures and mechanisms for oil burners:

• Light Dependent Resistor (LDR): This component, also known as a "cad cell control", "master control", or "fire-eye control", detects the flame and ensures proper ignition. The LDR's resistance changes based on the amount of light it is exposed to, with lower resistance when exposed to light from a properly ignited flame.
• Exhaust Stack Control: Older oil burners used a bimetallic heat-sensing element protruding into the exhaust stack. This "stack relay" or "stack control" sensed the heat of the exhaust gases to confirm ignition, serving a similar function to the LDR in newer systems.
• Electromagnetic Valve: This valve allows fuel to be shut off from the sprayer by electrical control, helping to avoid drips and facilitating the purging of fuel mist during startup or restarting. This safety mechanism prevents the oil-air mixture from exploding.
• Fuel Pressure and Nozzle: Proper fuel pressure and nozzle maintenance are crucial for safe operation. Nozzles should be replaced regularly as they can become clogged or worn, affecting fuel atomization and burner efficiency. Fuel pressure should be set correctly, typically around 100 psi, to ensure optimal fuel delivery and atomization.
• Maintenance and Troubleshooting: Regular maintenance and timely interventions are essential for safety and performance. This includes cleaning, inspecting electrical connections, verifying the fuel supply, and testing safety controls. Understanding common issues and their resolutions can help prevent accidents and ensure efficient operation.
• Safety Gear: When working with an oil burner, it is important to wear safety goggles, insulated gloves, a face mask, and keep a fire extinguisher nearby. Ensuring burner is unplugged before servicing, keeping flammable materials away, and allowing it to cool before handling are also crucial safety precautions.

Oil burner ignition

The ignition process in an oil burner is a critical aspect of its overall functionality and performance. Here is a detailed overview of the oil burner ignition process, along with some specific instructions and considerations:

Understanding Oil Burners

Oil burners are devices attached to oil furnaces, water heaters, or boilers, and they play a crucial role in igniting heating oil or biodiesel fuel. This ignition process generates heat, which is then transferred to either air or water through a heat exchanger. One of the most common types of oil burners is the "vaporizing gun burner," often used in residential home heating systems.

Ignition Process

The ignition process in an oil burner typically involves several key components and steps:

• Fuel Atomization: The fuel, such as heating oil or biodiesel, is forced under high pressure through a nozzle. This results in the fuel being atomized into a fine spray with a specific flow rate, angle of spray, and pattern, usually in the shape of a cone.
• Ignition Source: The atomized fuel spray is then ignited by an electric spark. This spark is generated near the end of a blast tube, where air is forced through by a fan driven by the oil burner motor.
• Fuel Pump and Motor: The fuel pump plays a vital role in pressurizing the fuel and delivering it to the nozzle. It is typically driven by a capacitor start motor, which ensures consistent fuel supply.
• Adjustable Heat Output: The heat output of the burner can be adjusted by regulating the rate of fuel delivery via the nozzle. This is often achieved using an adjustable pressure relief valve between the pump and the nozzle.
• Electromagnetic Valve: This component allows for precise control of fuel delivery to the sprayer. It helps prevent drips when the valve is closed and facilitates the purging of fuel mist during startup or restarting.
• Fan and Combustion Chamber: The fan, powered by an electric motor, blows air into the combustion chamber, where the ignition of the fuel spray takes place.
• Safety Mechanisms: Oil burners are equipped with safety mechanisms to confirm proper ignition. These mechanisms, such as cad cell controls or fire-eye controls, use light-dependent resistors to detect the presence of a flame.

Fuel Pressure Considerations

Maintaining appropriate fuel pressure is essential for the efficient and safe operation of an oil burner. Typically, the fuel pressure in an oil burner should be set at around 100 psi (pounds per square inch). However, it's important to refer to the specific manufacturer's recommendations for the given oil burner model. Deviating from the specified fuel pressure settings can impact the performance and safety of the burner.

Ignition Troubleshooting

If you encounter issues with the ignition of your oil burner, there are several factors to consider:

• Air and Oil Handling Systems: Ensure that the blower wheel is in good condition and that the combustion head is operating within its specified range. Check for any damage or obstructions in the combustion head and make sure the static plate is functioning correctly.
• Fuel Quality and Contamination: The quality of the fuel can impact ignition. Contaminants such as water, dirt, bacteria, or sludge in the oil storage tank can lead to ignition problems. Regular cleaning and maintenance of the oil handling system are crucial.
• Nozzle Condition and Alignment: A clogged or partially plugged nozzle can affect the ignition process. Check the nozzle for any blockages and ensure it is properly aligned and concentric with the combustion head.
• Cold Oil Temperatures: Cold oil can increase viscosity and lead to larger oil droplets, making ignition more challenging. Adjusting the pump pressure and nozzle size can help mitigate this issue.
• Ignition Components: Inspect the ignition components, such as the spark plug or glow bars, for any damage or wear. Ensure they are functioning correctly and producing the necessary spark for ignition.

Maintenance and Tune-ups

Regular maintenance and tune-ups are essential for optimal performance and longevity of your oil burner. This includes tasks such as replacing the nozzle, filters, and fuel pump, as well as cleaning the heat exchanger and ensuring the system is in good working order. It is recommended to have annual or biennial tune-ups performed by qualified technicians to reduce wear and extend the lifespan of your oil burner.

Oil burner troubleshooting

Step 1: Check the basics

Before you do anything else, check the thermostat. Is the fan mode set to “automatic?” Is the thermostat set to “heat?” If not, adjust the settings and see if that solves the problem.

Next, check your fuel oil supply. Don't just rely on the gauge — gauges are prone to failure. Unless you just had it filled recently, check the fuel tank itself. Use a dipstick to determine how much fuel you have.

Step 2: Inspect the furnace

Can you hear the furnace running? Is the cabinet warm to the touch? If not, the air filter may be so dirty it's blocking the flow of warmed air. Remove the filter. If the furnace then starts working, you've found the problem. Install a clean filter ($3-$30, depending on make and model) and you're done.

In rare cases, clogged ducts can restrict airflow sufficiently to reduce the performance of your furnace. Duct cleaning is dirty work that’s best left to professionals.

Step 3: Check for leaks and soot

If the furnace still isn't working, look for two potential culprits: leaks in oil lines and soot in the burner chamber. Leaks let air into the system, which can hurt performance. Soot indicates inefficient combustion that can lead to other problems. Either condition should be corrected by an expert.

Step 4: Listen for trouble

If the furnace is making a knocking sound, you likely have air in the lines. Purging the air -- called bleeding the lines -- isn't difficult, but it can frustrate a beginner. If you’re not confident, have your system checked over by a service pro.

A clattering sound may mean that the access panels on the furnace have worked loose and are rattling. A squealing sound probably indicates problems with a belt or the blower motor. Shut down the furnace, check the belt, and put just a few drops of electric-motor oil in any oiling ports on your firing assembly fan (some sealed units run oil-free, so you may not have ports).

Step 5: Check the air filter, oil supply, and oil filter

If the furnace sounds like it's running intermittently, check the air filter first. Then check your oil supply and filter. If the tank is full and the filters are clean, it's time for a service call focusing first on the burner nozzle and electrodes that ignite the fuel.

Frequently asked questions