Setting Fuel Pressure: Oil Furnace Guide

Setting the fuel pressure on an oil furnace is a simple task that can be done in a few minutes. Here is a step-by-step guide on how to do it:

First, locate the front access panel of your furnace and unscrew it using a Phillips screwdriver. If your furnace doesn't have screws, simply lift the panel to detach it.

Next, find the metal box containing the valves on the gas pipe. This is usually along the lower part of the access point. The gas pipe typically runs from the wall of your home to the furnace.

Now, identify the gas valve. It is a large, round tower with a metal screw sticking out of its top. Most furnaces have only one valve, but some two-stage furnaces have separate high and low-pressure valves.

Before adjusting the valve, ensure your furnace is turned on and the pilot light is lit. If not, locate the pilot light switch near the gas valve and turn it on. Wait for a few minutes, then relight the pilot light using a long stem lighter.

To adjust the gas pressure, you will need a manometer, which is a device that measures gas pressure. Connect a clear hose to the barbed tip of the manometer. Then, plug the manometer into the outlet port of the valve using a tube adapter.

If your furnace has two valves, start with the taller valve, which controls the high-pressure setting. Check the safe pressure setting listed near the valve or on the manufacturer's stickers.

Turn on the manometer and adjust the valve using a flathead screwdriver. Rotate the screw clockwise to increase the gas pressure and counterclockwise to reduce it. Set the pressure according to the manufacturer's recommendations.

If your furnace has a low-pressure valve, locate it near the high-pressure valve. It will be noticeably shorter. Adjust the thermostat to a low temperature so the high-pressure valve shuts off.

Finally, adjust the low-pressure valve to the recommended setting, usually 1.6 WC for natural gas. Again, use a flathead screwdriver and turn the screw clockwise to increase the pressure and counterclockwise to reduce it.

Once you've made the necessary adjustments, remove the manometer, close the outlet port, and secure the front access panel of the furnace.

It is important to note that gas furnaces can be dangerous if mishandled. If you notice gas leaks or other serious issues, contact a licensed heating and cooling specialist for assistance.

The relationship between pump pressure and nozzle size is critical

The pump pressure and nozzle size must be matched to the specific oil burner and boiler or furnace being used. The manufacturer will usually specify the acceptable range of nozzle sizes and pump pressures for a given burner. Changing the nozzle size or pump pressure can affect the burner's efficiency, flame length, and spray pattern.

Nozzle size is typically measured in gallons per hour (GPH) or litres per hour (LPH) and indicates the capacity of the nozzle to deliver heating oil. The pump pressure is usually set to 100 psi for residential oil burners, but some modern burners may be designed to run at higher pressures of up to 140 psi.

Increasing the pump pressure can allow for a smaller nozzle size while still maintaining the same fuel input. For example, a 1-GPM nozzle at 100 psi can deliver the same amount of fuel as a 0.75-GPM nozzle at 140 psi. However, it is not advisable to change the nozzle size or pump pressure unless there are issues with the burner, as it can affect the burner's performance and efficiency.

The spray pattern of the nozzle is also important, and there are three basic types: solid, hollow, and semi-solid (or universal). The spray pattern is designated by a letter stamped on the nozzle, such as "A" for hollow or "B" for solid. The spray angle, measured in degrees, indicates the width of the spray pattern. A wider spray angle is typically used for shorter, wider combustion chambers, while a narrower spray angle is used for longer, narrower chambers.

In summary, the relationship between pump pressure and nozzle size is critical to ensuring efficient and safe operation of an oil furnace. The nozzle size, pump pressure, and spray pattern must be matched to the specific burner and boiler or furnace, and any changes can affect the burner's performance and efficiency.

Higher pump pressure results in a finer oil mist

The oil pump is one of the most important parts of an oil furnace. The pump works to supply oil to the oil burner motor, which then sprays out a high-pressure stream of oil and ignites it so that the furnace runs and produces heat. The pump output can be adjusted on most fuel units, typically within a range of about 100 psi up to 150 psi.

However, it is important to note that simply raising the pump pressure will not proportionally increase the amount of oil delivered. For example, if you have a boiler designed to run at 1.00 GPH and you install a 1.00 GPM nozzle, the nozzle is rated to deliver one gallon per hour at 100# (pounds) of pressure, and 100# ONLY. If you raise the oil pump pressure to 200#, the nozzle will not deliver twice as much oil, but roughly a third more. This could exceed the boiler's capacity and destroy it over time.

Therefore, when increasing pump pressure, it is critical to also adjust the nozzle size and use a "nozzle firing rate chart" to determine the REAL firing rate. Additionally, without a combustion test apparatus, you cannot determine the results of your adjustments and could create a dangerous situation. It is always best to consult a professional when making any adjustments to your oil furnace.

A combustion test apparatus is needed to determine the results of tweaks

When adjusting the fuel pressure on an oil furnace, it is crucial to have a combustion test apparatus to determine the results of your tweaks. Without it, you risk creating a dangerous situation with potential smoke, carbon monoxide (CO), and excess air issues. Here's why a combustion test apparatus is necessary and how it helps:

Safety First:

The primary goal when working on an oil furnace is safety. Carbon monoxide (CO) is a highly toxic gas, and even small amounts can be dangerous. A combustion test apparatus helps you monitor CO levels during and after adjustments to ensure they remain below the allowable limit of 400 parts per million (ppm) air-free. Anytime CO levels rise or become unstable, immediate action is required.

Combustion Analysis:

A combustion test apparatus provides critical data for combustion analysis. It measures oxygen (O2) and carbon dioxide (CO2) levels, flue gas temperature, and draft, among other parameters. These measurements help you fine-tune the furnace for optimal performance while maintaining safe combustion conditions.

Fuel Pressure and Nozzle Size Relationship:

The relationship between fuel pump pressure and the nozzle size is critical. Adjusting the fuel pressure without considering the nozzle size can lead to overfiring or underfiring the boiler, resulting in premature equipment failure. A combustion test apparatus helps you understand this relationship and make informed adjustments.

Smoke Testing for Oil Burners:

For oil-fired systems, complete combustion testing includes smoke testing. While it is commonly believed that a smoky oil flame will produce CO, years of testing have shown that CO can be generated without visible smoke. Smoke testing helps identify incomplete combustion, ensuring that your adjustments result in a clean and efficient burn.

Fine-Tuning and Efficiency:

The combustion test apparatus allows you to fine-tune the furnace for optimal performance. By monitoring O2 and CO2 levels, you can adjust the fuel-air mixture to achieve a clean burn with minimal excess air. This not only improves efficiency but also reduces the formation of harmful pollutants like nitrogen oxides (NOx).

Identifying Problems:

The combustion test apparatus can help identify issues with the furnace or its components. For example, an increase in excess air readings when the blower starts or a decrease when it stops may indicate a heat exchanger crack. Draft tests can also reveal problems with the chimney or draft hood.

Meeting Manufacturer Specifications:

Different furnaces have specific operating requirements. The combustion test apparatus helps you ensure that your adjustments meet the manufacturer's specifications for fuel pressure, O2 and CO2 levels, stack temperature, and other parameters. This is crucial for safe and efficient furnace operation.

In conclusion, when making adjustments to the fuel pressure on an oil furnace, a combustion test apparatus is essential for safety, performance optimisation, and problem identification. It provides critical data for combustion analysis, ensuring that your tweaks result in a safe, efficient, and properly functioning furnace.

The oil pump pressure can be adjusted with a flathead screwdriver

Step 1: Locate the Hydraulic Pump's Pressure Adjustment Screw

The pressure adjustment screw is usually located at the front or back of the pump. It is important to find this screw first before attempting to make any adjustments.

Step 2: Open a Valve to Relieve Hydraulic System Pressure

Before making any adjustments, it is crucial to relieve the pressure in the hydraulic system. Locate the release valves and open them to release the pressure. This step is important for safety reasons.

Step 3: Use a Flathead Screwdriver to Loosen the Locknut

Use a flathead screwdriver to loosen the locknut on the adjustment screw. This will allow you to turn the adjustment screw and make the necessary changes to the pump pressure.

Step 4: Turn the Adjustment Screw Clockwise or Anticlockwise

Now, you can turn the adjustment screw to increase or decrease the pump pressure. Turning it clockwise will increase the pressure, while turning it anticlockwise will decrease the pressure. Make sure to refer to your hydraulic pump's user guide for specific instructions and safety precautions.

Step 5: Recheck the Output Pressure

After making the adjustments, it is important to recheck the output pressure to ensure that it is at the desired level. You can use a pressure gauge to measure the output pressure accurately.

Adjusting the oil pump pressure is a crucial step in ensuring the proper functioning and longevity of your hydraulic system. It is important to follow the correct procedures and safety precautions when making any adjustments to your equipment. Always refer to the user manual or seek professional assistance if you are unsure about any steps.

The oil pump pressure can be checked with a manometer

• Find the oil pressure sender. This is a small black cylinder that reads the oil pressure and is usually located on the top or side of the engine block.
• Remove the electrical connector from the oil pressure sender.
• Using a wrench, remove the oil pressure sender from the engine block.
• Attach an oil pressure gauge to the sender port. Ensure that the end of the gauge's hose matches the style port on the engine.
• Turn on the vehicle and take a reading from the gauge.
• Compare the reading to the recommended pressure range for your specific vehicle, which can usually be found in the user manual.
• If the pressure is significantly lower or higher than the recommended range, there may be an issue with the oil pump or another component in the system.

It is important to note that checking the oil pump pressure is different from setting the fuel pressure on an oil furnace. To set the fuel pressure on an oil furnace, you would need to adjust the fuel pump according to the manufacturer's instructions. This typically involves adjusting a screw or knob to increase or decrease the fuel pressure. It is recommended to consult a professional or the furnace's manual before attempting to adjust the fuel pressure on an oil furnace.

Frequently asked questions