Replacing Your Oil Tank Fuel Gauge: A Step-By-Step Guide

If you're having trouble determining the amount of oil in your tank, it may be time to replace your oil tank gauge. This can be done by yourself if you are handy and know your way around an oil tank, or you can contact an HVAC technician to replace it for you. This process involves first understanding how your float gauge works, then loosening the fitting, pulling up the disc, and loosening the fitting completely. Once the fitting is completely loose, you can remove the float assembly and install your new float gauge.

Understanding how a float gauge works

A float gauge is a device that sits inside your oil tank and displays the level of oil remaining in your tank. It does not show the number of gallons inside but instead measures what percentage of your heating oil tank is full or still available.

The float gauge works by using a floating piece (the 'float'), which sits at the end of a hinged arm. The float is usually made of cork or, more recently, plastic, and sits atop the oil. As the oil level lowers, the float moves down with it. At the other end of the hinged arm is a plastic disc that moves up and down with the float. The disc is housed behind a plastic vial that can be removed by hand. The disc and vial together provide a rough indication of the oil level in the tank.

Over time, the float can get stuck or weighed down by sludge, causing it to no longer read properly. The thin metal piece connecting the hinged arm to the disc can also get bent, or the whole assembly can rotate inside the tank, causing the float to get wedged against the inner wall. This will prevent the float from moving up or down, and the gauge will need to be replaced.

To replace a float gauge, you will need to loosen and remove the old assembly, pull up the disc to lift the float out of the oil, and then completely loosen and remove the fitting. You can then install a new float gauge by reversing these steps, ensuring that the float can extend into the open area of the tank without hitting the inner wall.

Signs that your float gauge is broken

A broken float gauge will not be able to accurately measure the amount of oil or fuel in your tank. Here are some signs that your float gauge is malfunctioning:

• Erratic Gauge Behaviour: A rapidly fluctuating or erratic fuel gauge could indicate a faulty fuel sender unit. If your gauge is functioning correctly, it should continuously move towards empty until you fill up the tank. A faulty sender unit might cause the gauge to abruptly change position or give an incorrect reading.
• Gauge Stuck on Empty: If your fuel tank displays empty even when it is not, it could be due to the float snapping or separating from the arm. This problem can also be caused by a faulty resistor in the system.
• Gauge Stuck on Full: Although less common, a defective resistor could cause the gauge to be locked at full. Alternatively, the transmitter might be to blame if the resistor is functioning correctly.
• Sludge Buildup: Over time, sludge can build up on the float, causing it to no longer float properly. This is a common issue with older heating oil tanks.
• Bent or Broken Metal Arm: The thin metal arm that connects the float to the disc can bend or break, especially if you push down on the disc.
• Assembly Rotation: The entire assembly can rotate inside the tank, causing the float to get wedged against the inner wall. This will prevent the float from moving up or down, and the gauge will become stuck.
• Corroded Wires: Corroded wires, especially in the case of a fuel sending unit located on the fuel pump, can interrupt the voltage and cause the gauge to malfunction.

If you notice any of these issues, it is recommended to consult a professional or refer to a repair guide for guidance on replacing or fixing your float gauge.

Tools required to change the gauge

Replacing the gauge on your oil tank is not a very difficult task if you are handy with tools. However, it is important to note that if you are uncomfortable with the process or encounter any difficulties, it is best to contact a professional for assistance.

• Rubber gloves and old clothes: It is important to protect your skin and clothes from the heating oil, as it has a strong smell and can cause stains.
• A wrench, preferably a 14" pipe wrench or bigger: You will need this to loosen and tighten the fittings on the oil tank.
• Pipe dope or thread sealant: This will be used to seal the threads of the new gauge and ensure a tight connection.
• Penetrating oil or Liquid Wrench (optional): If the fittings are difficult to loosen, you can soak them in penetrating oil for several hours or days to make them easier to turn.
• Paper towels and a garbage bag: The process of removing the old gauge and installing the new one can be messy, so it is a good idea to have these items on hand to catch any dripping oil and dispose of the old gauge assembly.
• A marker: You will use this to mark the fitting to indicate the direction in which the arm of the new gauge should fall once it is installed.
• A flashlight (if needed): If your oil tank is in a dark area, you may need a flashlight to see the gauge and fittings clearly.
• A gauge stick, yardstick, or metal rod (optional): While not necessary for installing a new gauge, it is a good idea to have one of these tools on hand to manually check the oil level in your tank.

Step-by-step guide to changing the gauge

Step 1: Prepare

Before you begin, make sure you have the right tools and safety equipment. You will need: rubber gloves, old clothes, a 14" pipe wrench (or bigger), pipe dope/thread sealant, and penetrating oil (optional). It is also recommended to have paper towels and a garbage bag ready for any oil spills during the process.

Step 2: Understand the float gauge mechanism

The float gauge consists of a floating piece ("float") made of cork or plastic that sits atop the oil. This float is attached to a hinged arm, with a plastic disc at the other end. The disc moves up and down with the float and is housed behind a removable plastic vial. Together, the disc and vial provide a rough indication of the oil level in the tank. Over time, the float can get stuck or weighed down by sludge, leading to inaccurate readings.

Step 3: Loosen the fitting

Start by removing the plastic vial by hand to expose the disc. Then, use the pipe wrench to loosen the metal fitting that threads into the tank. Be careful to only loosen it slightly (no more than half a turn) to avoid the float hitting the inside wall of the tank. If the fitting is difficult to loosen, you can soak it in penetrating oil for several hours or a couple of days to make it easier.

Step 4: Pull up the disc and fully loosen the fitting

Use both hands to pull the disc up as far as it will go, lifting the float out of the oil. This will allow you to rotate the assembly without it crashing into the inside of the tank. Once the disc is fully raised, continue unscrewing the float gauge fitting from the tank.

Step 5: Remove the float assembly

With the fitting completely loose, you can now remove the float assembly. Release the disc to allow the float to settle back into the tank. Slowly raise the assembly out, allowing the float to fall, and catch any dripping oil with paper towels. Place the old assembly immediately into the garbage bag.

Step 6: Install the new float gauge

To install the new float gauge, reverse the previous steps. Start by cleaning the fitting on the tank and applying pipe dope to the threads of the new float gauge assembly. Mark the fitting to indicate the direction the arm should fall once the assembly is on the tank, ensuring the float doesn't hit the inner wall. Gently lower the float into the tank until the fitting mates with the tank.

Step 7: Secure the new float gauge

Lift the disc to raise the float out of the oil, then hand-tighten the assembly as far as you can. Continue lifting the disc and tighten with the pipe wrench until snug. Stop tightening once the arm is oriented properly in the tank. Finally, secure the plastic vial in place by hand-tightening it.

Benefits of installing a Smart Oil Gauge

A smart oil gauge is a clever device that syncs with an app and gives you a complete overview of your oil usage, when to place an order, and how much you have spent. It is compatible with most devices, such as a laptop, tablet, or smartphone. Here are some benefits of installing a smart oil gauge:

Remote Oil Tank Monitoring

You can check your heating oil tank from your smartphone or tablet anytime, from anywhere with internet access. This is especially useful if you have a second home or a rental property, making it super easy to monitor oil tanks.

Never Run Out of Heating Oil

With a smart oil gauge, you will be immediately notified when levels are low, so you can place an order right away. No more standing in the cold or forgetting to check.

Automated Delivery

The smart oil gauge can organise your top-ups for you. It can assess when your heating oil is low and arrange your order for the most effective time. This feature can be turned off if you prefer to order manually.

Financial Overview

The smart oil gauge can show you a complete overview of your spending in comparison to your usage, helping you keep a tighter grip on your finances. It can also help you understand your heating oil usage by showing you exactly how many gallons you are using each day and when your highest usage times are.

Use on Multiple Devices

The smart oil gauge can connect and send alerts to a PC, mobile, or laptop. This means anyone you live with can also take responsibility for monitoring oil levels. It also connects to Alexa, making it even easier to find out when your next heating oil order is due.

Protect Your Assets

In the unfortunate event of a leak or theft, a smart oil monitor with an app will immediately notify you of any unexpected drops in the oil level, allowing you to take action immediately, no matter where you are.

Simple and Affordable Setup

Setting up a smart oil gauge is simple and affordable. Everything you need is included in the package, and if you don't feel comfortable setting it up yourself, a trained installation specialist can help you.

Frequently asked questions