Leaking Boiler Repair and Maintenance

boiler leaking from the bottom
  • 1-3 hours
  • Intermediate
  • 5-30
What You'll Need
Old rags
Fairy liquid
Hot water
What You'll Need
Old rags
Fairy liquid
Hot water

An efficient boiler adds to the comfort of our daily living experience. It performs an essential water heating role to meet household needs. Boilers for home use may be powered by oil, natural gas, or electricity.

Depending on your model, the system may sometimes leak oil, giving you a leaking boiler. This may be caused by a damaged valve or pipe in the heating system. The fuel pipe or other parts may be loosely attached.

Components in the burner may also be defective. A persistent leak may cause stains to develop on the floor. It may also give rise to an unpleasant smell if left unattended.

Here's what you can do if you spot an oil leak. There's also a lot of maintenance you can do to prevent issues in the first place.

If you feel ill-equipped to handle these repairs yourself, call in the professionals. It will cost more but will offer you a lot of piece in mind. And having them address small problems early on will prevent larger problems from arising at a later date.

Step 1 - Turn Off

For most projects, the first step is to turn off a power source and this is not different. Before you begin your repair work, be sure to turn off the heating system.

This may seem like a small thing, but it is necessary in order to ensure that you work in a safe environment. Do not skip this step.

Step 2 - Inspect

Carefully check the entire heating system to detect the exact source of the leaking in the system. This will help you determine where to focus your repairs and gain knowledge about the issue facing your leaking boiler.

Step 3 - Tighten Components

hand tightening parts on boiler

As you inspect the system, you may come across some loose components. The fuel pipe may be insecurely fitted. If so, tighten it to give a firm fitting. Loose attachments may allow oil to seep through during operations.

If the boiler stops leaking after this, you are done. If not, move on to the next step.

Step 4 - Replace Damaged Components

It is best to replace any damaged parts you identify. Detach the faulty component and take it with you to a boiler dealer. This will ensure that you get the right replacement.

Once you get the new part, put it on your boiler, replacing the old part. You can also order new parts online.

Step 5 - Open the Burner

The burner performs the heating function. Oil leakage sometimes occurs here. If leakage is from the filter or fire valve, the top of the burner should be wet. A dry top indicates the problem may be from elsewhere within the burner. Use a screwdriver to remove the burner top.

Place screws and top in a convenient place for easy retrieval later. You may want to put them in a baggie so they do not get loose. Do not misplace these or the rest of the steps will be much more complicated than need be.

Step 6 - Inspect Oil Line

The oil line is attached to the oil pump. Carefully inspect the oil line to determine if it is okay. Any worn out or damaged areas could allow oil to seep through. It is best to replace the oil line if it appears faulty. While some DIYers can do this, novices may want to get professional help if the oil line is deemed to be the issue with your boiler system.

Step 7 - Inspect Oil Pump

Check the screws and plugs on the oil pump. These may have been loosened during maintenance, such as bleeding the system. This can allow leakage to occur. Be sure to tighten components if you find they are loose.

Step 8 - Identify Hydraulic Jack

This hydraulic jack may also cause oil to leak. The component could have been damaged during operations or previous maintenance work. It could also have worn out. A faulty hydraulic jack has to be replaced quickly. Remove the item and take it with you to a dealer to get a fitting replacement.

Step 9 - Close the Burner

Retrieve the burner top and screws from storage. Attach as before. Turn the system on. No more oil leakage should be evident.

Step 10 - Clean

Use fairy liquid and lots of hot water to clean oil stained areas around the boiler. There could simply be some debris that needs to be eliminated in order to ensure your system works properly.

Boiler Maintenance

hands opening wall mounted water heater

With any major appliance, you can avoid a lot of repairs by regularly maintaining the device. Your boiler is no different. This is easily accomplished. First, you have to verify the reading on the water gauge against the water that is actually in the boiler.

Next, test the relief valve. While the boiler is running, raise the valve. Steam should be discharged for a short while before stopping. If steam discharge continues, you’ll need to replace the valve.

Boiler maintenance is a must if you hope to have your boiler efficient at all times. Boilers give a vital service in hot water supply and household warming. They add to the comfort level of the home. Too often, repairs become necessary when the boiler malfunctions.

Regular maintenance can help avert ceaseless repairs. This will help you save hundreds if not thousands of dollars on overall costs. Maintenance is also advised to avert accidents and boost household safety. Maintenance will also boost the efficiency of your boiler and extend its life span. Below are some maintenance tips.

Air Vents and Flues

Blocked air vents hamper the boiler from working efficiently. This particularly applies to gas boilers. Dirt may accumulate in vents or flues and cause a blockage. It is a good idea to inspect vents and flues regularly. If any blockage has occurred, clear it to allow the free passage of air.

Water Level

It is vital that you check the boiler water level every fortnight or so. Should the boiler operate without water, this can easily damage it beyond repair. It can also cause an accident and endanger the lives of family members.

Be sure that the pilot light is on as you check the water level. If the water level is below the minimum, you need to check the plumbing and correct any faults. Sometimes, all that is required is a few minor adjustments in the setup. Sometimes, however, bigger repairs will become necessary.


Sometimes leaks will occur during normal usage of the boiler. Gas or fuel may leak through the valves. This usually indicates some adjustments are necessary to the system. If you detect damaged or worn out parts, this calls for repair or replacement as quickly as possible.


Hard water usually gives rise to excessive lime-scale in the boiler. This prevents the boiler from working as it should. If left to accumulate, lime-scale will hamper the heating capacity of the boiler.

You will need to de-scale your boiler should you notice too much lime-scale within it. Check your owner's manual for instructions on how to do so without damaging the boiler itself.


Regular lubrication is essential for the smooth operation of most mechanical systems. Your boiler will benefit from routine lubrication, as this will support its working capacity. Be sure to lubricate boiler parts that are frequently in motion, such as the fan and pumps.

Clear Dust

Dust easily accumulates in the boiler room because of the boiler operations. Check the boiler room regularly and clear any dust in sight. Pay particular attention to the boiler parts as dust accumulation will affect the system from working well.

The fan often develops much dust build-up. Be sure to clear all dust to enable optimal efficiency. Be gentle when clearing dust from the boiler so as not to damage anything or push the dust further down in the system.

Gas Boiler

You can carry out many types of gas boiler repairs yourself. More complex repairs will require professional help, but some common problems are fairly simple to fix. Learn more about these common problems below.

No Heat

When no heat comes from the boiler, there could be several potential causes. First, you should check the circuit breaker (or fuse). If it is in the "Off" position, switch it to "On" and try the furnace again. This is an easy fix.

In the case of a damaged fuse, you will need to replace it.

If the pilot light has gone out, activate it by following the instructions on the boiler. Make sure the thermostat is in "Heat" mode, and turn the thermostat up a few degrees to see if the boiler kicks in.

Check the water in the boiler. It should be half full and between 12 to 15 PSI. You can adjust it with the pressure-reducing valve. If your unit doesn't have a pressure-reducing valve, open the water-feed valve until the pressure is set at 12 PSI.

Low Boiler Heat

If you suddenly find inadequate heat coming from the boiler, the problem will inevitably be low pressure in the boiler. You can read the boiler pressure reading on the indicator.

If the level is under 12 PSI, the boiler needs more water. In most cases, the pressure-reducing valve will rectify this automatically. If you don't have a pressure-reducing valve, follow the directions in the previous section.

Where there’s been a gradual reduction in heat over a period of time, it’s a good sign that the boiler needs to be flushed. You can do this yourself instead of calling in the professionals, thus saving you a lot of money.

Boiler Water Leakage

large boiler with water around the base

If you find water around the boiler, the problem will be due to a leaking connection in the pipes, a faulty pump, or a faulty pressure-relief valve.

Where the pump is the cause of the leak, you can carry out a simple gas boiler repair that requires the removal of the pump and a new pump seal.

If the pressure-relief valve is at fault, try turning off the boiler until the water cools. Open the manual pressure-relief valve for 3 seconds and allow some water to discharge. If the valve continues to leak afterward, open it again to let any trapped sediment flow out.

If the valve will not close, you will need a more complex gas boiler repair to replace the valve. If no water appears when you open the valve, you'll know the valve is plugged and must be replaced. (Check that there is water in the boiler before doing this.)

Noisy Pipes

Nobody wants noisy pipes as they can be quite a nuisance. They can also be a sign of a bigger problem.

Especially noisy pipes may result from water in the return lines or a faulty circulator pump. If water is trapped in the return lines, it will usually happen because the line is no longer pitched down toward the boiler. You can rectify this condition with a simple gas boiler repair; you can use a pipe hanger to change the angle.

If the problem is in the circulator pump, check for a broken spring-loaded coupling that connects the pump to the motor.


If you have a leaking boiler, the above tips will help you fix the issue to get your boiler working like new. Make sure to also perform regular maintenance on the boiler system. This will prevent issues from happening in the first place and save you money on costly repairs in the long run.

Boiler maintenance should be part of your quarterly home checks. Make sure to take a little time, even just a few minutes will do, to check on the boiler. While the device is usually out of sight, it should not be out of mind and should be given the care and attention it deserves.

If the above ideas do not solve any issues with your boiler, it's time to call in the professionals to help you fix the boiler and ensure it has a long life keeping you and your loved ones warm and safe.