Heating oil tank cleaning in 5 steps


Knowing how to clean your heating oil tank is important. The entire heating and hot water system obviously depends on the quality of the oil and the fuel flowing unhindered to the burner. If the oil tank is dirty or contains an obstruction preventing the oil from flowing to the burner, it might not provide a comfortable temperature for your home or hot water. Read on if you would like to learn how to clean your oil tank properly, effectively, and without too much effort.

How to clean a heating oil tank

You may have already wondered: How do I clean my heating oil tank? Or perhaps: How do I clean my oil fuel tank? This article will provide an excellent, step-by-step tutorial on how to do this.

It’s advisable to clean your heating oil tank after 10 years of use. After you’ve cleaned it for the first time at 10 years, you should continue to clean it every 5 years. How often you clean it also depends on what the tank is made from.

Cleaning a metal heating oil tank is not the same as cleaning a plastic tank. Metal ones require more maintenance, while plastic ones are practically maintenance-free. Plastic and metal tanks are cleaned in the same way but metal ones require additional maintenance. Let’s take a look at the tutorial on how to do this below:

Step 1: Empty the tank completely

Both metal and plastic tanks accumulate sludge due to the presence of water in the tank. This sludge needs to be completely removed. In addition to contaminating the oil, sludge also clogs the filter and the boiler’s taps, and much more.

The first step involves completely emptying your oil tank through the drain cock. If you want to reuse the uncontaminated oil in your tank (and not have to throw it away), you will need a container to pour it into.

Step 2: Remove the contaminated oil from the bottom of the tank

If you have a sludge accumulation at the bottom of your tank, it’s best not to reuse it. However, according to safety regulations, contaminated oil should not be disposed of into the environment, either. Any unwanted oil should be taken to a treatment plant with a special transport company.

Removing the sludge should be done using vacuum suction equipment. Boiler technicians typically have such equipment, or you could hire or buy the equipment yourself.

Any oil that has combined with the sledge will have settled at the bottom of the tank. It is for this reason that you shouldn’t wait too long between removing the useful oil and suctioning out the sludgy, oil mixture. Waiting too long could result in it drying out and adhering to the bottom of the tank.


Step 3: Disconnect the tank from the boiler system and remove it

Once you have emptied the tank (and have removed the useful oil and suctioned out the dirty oil), you should disconnect it from the socket connecting it to the boiler pump. Remove it and take it to a suitable place for cleaning.

It is important to block and elevate the pipe that goes into the oil pump. This is to avoid spilling any oil already in the system and to minimize the amount of air coming into the pipe. Once you have finished cleaning the tank, you should bleed the unit, taking care not to allow too much air to enter.

Step 4: Clean the tank with specialized products

Now you can start cleaning the tank. Even if you have not called in a technician to do the job, you will still need to hire special equipment. The special cleaning products and equipment exert pressure against the tank walls.

It’s not enough simply to clean the tank by hand as this will not work. In addition, you cannot use normal soaps or detergents, which are almost ineffective against impure oil and which can cause unexpected chemical reactions.

If you have a metal tank, after the cleaning process, you will need to polish the metal inside the tank. This will remove any rust that might have appeared and prevent it from appearing in the future.

Step 5: Reconnect the tank and fill it with oil

Once you have finished cleaning the heating oil tank, you can reconnect it and re-transfer the fuel that you removed in the beginning. This process must be precise and the oil requires a microfiltration process before it can go back into the tank. Alternatively, you could simply refill the system with the oil that you recovered before cleaning.

Frequently asked questions at Suner

How much does it cost to clean an oil tank?

The price for cleaning an oil tank varies. It largely depends on where you live. However, the main factor affecting the price depends on the size of your tank and how dirty it is.

Generally speaking, the price normally ranges from 250 to 500 Euros. Your best bet would be to contact whoever is going to perform the cleaning and agree on a specific price. Given how infrequently your tank needs to be cleaned and all the benefits cleaning brings, it is well worth the expense.

If for some reason, you don’t want to spend the money, you could always follow the above-mentioned tutorial for cleaning the oil tank yourself. It is a lot of hard work but luckily is not too difficult.

How long can oil remain in the tank?

We can approach this question in two ways. The first way refers to how long you can keep oil in the tank once you’ve filled it. The second way involves how long it takes for stored diesel oil to spoil.

The answer to the first way (the one referring to how long you can keep oil once your tank is filled) is that it depends. It depends on the size or capacity of the tank, the type of boiler, and how the boiler uses the fuel, which in this case will be a regular boiler, a mixed boiler, or a boiler heater. It also depends on the boiler’s energy efficiency, meaning how much power it’s able to generate for each unit of fuel. However, it is widely considered that a conventional 1000 liter oil tank can last between 2 and 2 and a half months when used 6 to 8 hours per day.

The answer to the second way (the one referring to the expiration date of diesel oil), you will be pleased to learn that diesel oil oxidizes very gradually but it’s still not a good idea to store it for too long without using it. Some products (such as anti-rust products, demulsifiers, stabilizers, etc) can be added to diesel oil to extend its useful life. However, generally speaking, diesel oil has a shelf life of 12 months. It is not recommended to store it for longer than a year.

If you don’t think that you’ll be using the diesel oil during the time period in which it’s likely to start oxidizing, it is better not to buy it. Diesel oil that contains rust or is impure can damage your tank, the pump, and even the burner and other components in your boiler or burner. In addition, when oxidized diesel oil starts to combust, it has a higher polluting potential.

How can diesel oil be neutralized?

“Neutralizing diesel” helps to eliminate the smell that is produced after a leak or simply the natural smell of diesel. The diesel neutralizing process refers to the process that qualified technicians use in these cases.

Wherever there is an oil tank (especially if it is a large one that is typically used for heating), the diesel oil smell can filter into the surrounding environment and onto clothes and other surfaces.

Neutralizing diesel oil is useful if you want to enjoy an environment that doesn’t have a diesel oil smell. Some people actually like the smell of diesel oil, but they are definitely not in the majority. Most people prefer not to have the smell of diesel oil in their homes.

As mentioned, the diesel neutralizing process should only be carried out by a qualified technician. It involves applying an environmental trioxygen treatment (this is ozone, which has the formula O3). This procedure also requires the use of special cartridge masks (IP3). Unpleasant environmental odors from diesel oil can also be neutralized using filters that use activated carbon.


Removing the diesel oil odor from other surfaces is different in each case. It all depends on where the odor is. Let’s take a brief look at how to neutralize a diesel oil odor in some cases:

  • From the surrounding environment: First, establish whether the smell is emanating from a non-serious spill or if it is because of a leak. If it is because of a leak, attend to this problem first as it is dangerous. In this case, the odor would only be a secondary problem. Once the leak has been sorted out (if there is one) the first thing to do is to ventilate the building well (if you have not already done so) and call in a qualified technician who will neutralize the diesel using one of the methods seen above.
  • Hands: The next thing you need to do is wash your hands thoroughly with soap or detergent, and repeat the process if necessary. You can then use one of the following application methods: white vinegar, vanilla extract dissolved in water, lemon juice and water, or salt and dish detergent. Rub one of these solutions into your hands until they smell better. You can repeat the process if needed and then wash your hands again normally.
  • From clothing: A normal washing machine wash doesn’t remove the diesel oil smell in clothing. Clothing that smells of diesel oil should be washed separately. It is better to wash them by hand with a particularly strong detergent or with some Listerine. You may want to wash them more than once. Finally, you can apply an odor-elimination spray that you can buy anywhere.

From wood: Bicarbonate of soda is normally an excellent substance to eliminate the smell of diesel oil or other fuels that your wood has acquired. Simply apply some baking soda to the affected area. It is best to leave it for 24 hours in order to be effective and absorb well. Remove the bicarbonate of soda when it is dry and avoid removing it with water.

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