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8 Reasons Your Boiler Is Leaking Water & Ways to Fix

BoilerPicture this: You go to check on your boiler because you notice cycling issues and find water leaking underneath. This is a common problem with older boiler systems. Boiler leaks can lead to serious damage. From mold and fungi growth to dangerous health risks, boiler leaks should never be ignored.

You’ll need urgent attention from a heating professional. Modern boilers can achieve efficiencies as high as 98.5%, so it’s worth getting a replacement. To help you determine if it’s time to purchase a new system, we have compiled a list of issues that can be associated with your boiler leaking water.

Why Your Boiler Is Leaking Water

Read on to learn eight reasons why your boiler is leaking water.

1. Deterioration

Water can escape over time through deteriorating pipes in your hot water boiler as they start to weaken. If the deterioration does not spread to multiple pipes or valves, solving the boiler leak is a simple task. Replacing the deteriorated part can fix the problem. If the deterioration spreads to more than one pipe throughout the system, there is no repairing it. You’ll likely need to replace the boiler entirely.

2. Pressure

If the boiler pressure becomes too high, leaking water could be the result. To lessen the risk of the boiler imploding, it will release pressure and, therefore, release water. You can tell if your boiler is leaking water because of the pressure if the pressure gauge is above 2. Your boiler should read anywhere between 1 and 2 on the pressure gauge. Knowing how to fix a leaking boiler, in this case, is easy. Simply change the pressure to resolve the issue.

Thermometer3. High Water Temperature

Another possible cause of boiler leaks is high water temperature. Your boiler will have a temperature control valve (TCV) that should stop the temperature from rising too high. Scalding water may come out of the taps and must be fixed by a professional boiler repair service.

4. Insecure Joints

If your boiler is leaking water, this is a sign of wear and tear. Water leaks are more common in boilers older than 10 years. Boiler leaks can be caused by loose joints or pipe connections.

To prevent water from coming out, the joints must be tightened by a professional technician.

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5. Bad Installation

If you hire a boiler repair company that poorly installed your system, you could be experiencing leaks as a result. If water comes through the pipe fittings, poor installation is usually the culprit. To avoid this issue again, you must hire a reputable company staffed with registered engineers. They’ll have to install a new boiler for you.

6. Expansion Tank Failure

If you notice your boiler is leaking water, your expansion tank may be failing. Depending on the boiler, this piece could be located inside the boiler or separate from it. These tend to be difficult to replace. If you have a warranty for your boiler, you won’t have to pay to fix this problem. This issue is pretty common and can happen because of deterioration. The leak won’t begin until the boiler has been on for some time.

Boiler7. Boiler Is Worn Out

A boiler is under the most pressure and can get overworked during the wintertime. If a boiler fails in the winter, it’s a sign that it needs replacement.

You’ll know your boiler is worn out by spotting deterioration. If there is a lot of corrosion, it won’t be hard to find. A leak caused by an overworked boiler can come from underneath the boiler or outside of the overflow pipes. You may also find a boiler heat exchanger leak.

You can look for these leaks by checking the pipes and keeping an eye on different boiler parts. If the boiler doesn’t look too good, you should opt for a replacement boiler. A small level of corrosion is often an easy fix but requires professional help nonetheless.

8. Problems With the Heat Exchanger

The heat exchanger is the most expensive part of the boiler. They often fail if they are not of quality.

You likely won’t be able to spot this issue on your own. However, you may notice an odd smell and whistling or kettling noises. Water leaking on the floor is another sign you have a problem with the heat exchanger.

If you suspect problems with your heat exchanger, hire the professionals at ServiceMark right away.

What To Know Before Purchasing a New Boiler

If you need a boiler replacement because of a leak issue, you’ll need to take a few things into account. Use these key considerations before making a purchase:

TechnicianTypes of Boilers

Boilers can run on natural gas, oil, or liquid propane. When choosing a fuel to run on, check the availability in your area. This is very important—boilers can only run on a fuel to which your home has access to. Fuel rate and availability aren’t always uniform, which is why you’ll need to make sure you match them accordingly.

If there are multiple options to choose from where you live, a certified technician can help you make the right choice. It is not always the best idea to go with the cheapest.


If you are looking to keep your utility costs down, finding an efficient boiler is key. You can check the different efficiency levels of boilers by looking at their Annual Fuel Utilization Efficiency (AFUE) ratings.

The Federal Trade Commission requires new boilers to have their AFUE on display so consumers can compare efficiencies.

The most effective boilers will have ENERGY STAR certification and likely cost more upfront, but you’ll save a lot more in the long term.


When choosing a boiler capacity, think about the demands of your home. You don’t want a boiler that is too big or too small to avoid the risk of lessening the efficiency. Too-large boilers can lead to short cycling; too-small boilers may constantly overwork, leaving cold and hot spots throughout your home.

Many factors go into proper boiler sizing, which is why they are often mismatched. Without the help of a boiler service, you’ll run the risk of choosing the wrong boiler for your application. Allow a professional heating service to perform load calculations, and recommend the best-sized boiler for your home.

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Regular maintenance is required to keep your boiler working at max efficiency and avoid leaking issues. Part of the maintenance routine will include checking its parts and periodic cleaning.

Before buying a new boiler, ensure you understand the maintenance requirements. Your installation company should be able to conduct annual maintenance as well.

Water HeaterBoiler Repair & Installation Services

You’ve spotted a boiler leak, now what? If your boiler is leaking water, you should call the professionals right away. We offer dependable boiler repair and replacement services to homes in areas such as Drexel Hill, Ardmore, Easton, Wilmington, Upper Darby, and Elkton. We strive to provide credible heating services to homeowners. In addition, we offer other types of HVAC services such as air conditioning repair, heat pump installation, and furnace repair. Our team is filled with licensed technicians who go through performance training each year. We are ready to keep you comfortable in your home! Contact us now for boiler services or maintenance requests.

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