Top 6 Reasons Why Your Boiler May Be Leaking Water

6 Jan by Will Kruse

Top 6 Reasons Why Your Boiler May Be Leaking Water

If you have a boiler, chances are you’ve had a leak or two in your day. Boilers are pressurized systems; over time, that pressure can build up and cause a boiler to leak water. There are a few different reasons why your boiler may be leaking water, and each one requires a different fix.

In this article, we will discuss why your boiler may be leaking water, what you can do to diagnose and fix the issue, and how you can prevent it from happening in the future.

  1. Cracked Heat Exchanger 

    The heat exchanger is responsible for transferring heat from the combustion chamber to the water in the boiler. If the heat exchanger becomes cracked, water can leak out into the surrounding area.It is important to have a professional inspect the heat exchanger to make sure that this is the source of the leak. Usually, the best way to fix a cracked heat exchanger is to replace it.

  1. Faulty Pressure Relief Valve 

    The pressure relief valve is responsible for releasing excess pressure from the boiler when it gets too high. If the valve is not functioning properly, it can cause water to leak from the boiler. You should have a professional inspect the pressure relief valve to make sure it is working correctly.

  1. Blocked Condensate Pipe 

    The condensate pipe is responsible for carrying away excess water from the boiler. If the pipe is blocked, water can back up and leak from the boiler. To diagnose this issue, you should have a professional inspect the condensate pipe and clear any blockages.

  1. Faulty Seal or Gasket 

    Boilers contain several seals and gaskets that are designed to keep water from leaking out. Over time these seals and gaskets can become damaged or worn out, leading to leaks. Replacing these seals and gaskets is often the best way to fix the leak.

  1. Build up of Limescale 

    When water is heated, the calcium carbonate in the water starts to break down and form a hard, white substance called limescale. This build up can restrict the flow of water through the boiler, leading to a build up of pressure and eventually a leak.Make sure that your boiler is maintained regularly. This means having it serviced and cleaned at least once a year by a qualified technician. During this service, the technician will inspect the boiler for signs of limescale build up and take the necessary steps to remove it.

  1. Faulty Expansion Tank 

    A faulty expansion tank can be a big issue for your boiler and can lead to water leaks if not taken care of. Expansion tanks are a vital component of your boiler system and are used to help regulate the pressure of the hot water in your boiler.When the water in your boiler is heated, it expands, and the expansion tank helps to absorb this extra pressure. Without an expansion tank, the pressure can build up and cause the boiler to leak, leading to costly repairs and water damage.

    When an expansion tank is faulty, it can cause water leaks, loud banging noises, and high water pressure. If you notice any of these issues, it’s important to contact a professional as soon as possible to inspect and replace the expansion tank.


A boiler leaking water can be caused by a variety of things, including a cracked heat exchanger, a faulty pressure relief valve, a failed pump seal, a corroded heat exchanger, a broken thermostat, a blocked condensate pipe, faulty seal or gasket, or a faulty expansion tank.

It is important to identify the cause of the leak in order to determine the best course of action. If the cause of the leak is not apparent, it is best to contact a professional to assess the issue and take the necessary steps to repair it. Taking care of the issue quickly will help protect your home from further damage and ensure that your boiler is functioning properly.

Are you looking for a reliable plumbing, heating, and cooling company to service your boiler? Look no further than L.J. Kruse Co., a family-owned and -operated business in Berkeley, California. We offer a wide range of commercial and residential heating services, including boiler repair and service. Contact us today to get started!

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