Boiler Maintenance

A simple guide to boiler pressure

Published on
January 5, 2024
Text on a blue background that reads: Boiler pressure: everything you need to know. Next to this there is an image of a boiler pressure gauge

Boiler pressure: everything you need to know

At Padly, we understand that boiler pressure can be a confusing aspect of your heating system. Don't worry, our experts are here to put your mind at ease by breaking it down for you. In this guide, we'll delve into what boiler pressure is, how it affects your boiler's performance, and what the correct pressure should be. We'll also explore common signs of both high and low boiler pressure, along with their potential causes. Whether you're a seasoned homeowner or a first-time boiler owner, understanding boiler pressure is essential for a cosy and stress-free winter.

What is boiler pressure?

Boiler pressure measures the pressure of the water in your heating system and boiler. It is essential to ensure the proper functioning of your boiler and radiators. Too high or too low pressure can lead to issues, so maintaining the correct pressure is key. You can check your boiler pressure using the pressure gauge, which is a small dial usually found on the front of the boiler. This will indicate the pressure within your system to identify any leaks or pressure drops.

Why is boiler pressure important?

Boiler pressure plays a crucial role in determining the efficiency of your entire central heating system. Maintaining a stable and correct pressure level is key to ensuring your home stays warm, your water stays hot and makes sure your boiler is not under any unnecessary strain.

What's the correct pressure for my boiler?

The correct boiler pressure typically ranges between 1 and 1.5 bars, although it will vary depending on your boiler type, make and model. Our experts recommend consulting your boiler's manual to determine the right pressure for your specific system.

High boiler pressure

As your boiler produces more heat, the pressure naturally increases which causes your pipes to expand. A slight rise in pressure is normal, but it should stay within a certain range. If it shoots up too high, then problems can occur.

Signs your boiler pressure is too high:

  • The pressure gauge has moved into the red zone
  • Your central heating system has stopped working/shut down
  • The filling valves are loose or not properly secured
  • The pressure gauge is showing a reading of 0 pressure, which means the pressure release valve (PRV) has been activated as a safety precaution

Causes of high boiler pressure:

Our experts have listed below some of the most common causes of high boiler pressure:

  • Repressurising: If you repressurised your boiler when it was still hot, causing it to expand. It is imperative to always pressurise when your heating system is cold.
  • Faulty expansion vessel: The expansion vessel is designed to absorb excess pressure in the system. If there is not enough air in the expansion vessel, then pressure can rise beyond the normal range
  • Excessive water: Your boiler can have too much water in it which can cause high pressure
  • Aging boiler: If your boiler is over 10 years old and you are experiencing pressure problems, then the two are likely connected
  • Faulty components: There are multiple components in a boiler that are related to measuring and dealing with pressure. If these get damaged in some way or malfunction, then it could easily cause your pressure to increase

If you've noticed that your boiler's pressure is too high, our experts recommend acting quickly as it can be dangerous for boilers to operate on a high pressure level. To find out how to fix high boiler pressure see below.

How to fix high boiler pressure

Bleed the radiators

One way you can reduce boiler pressure is to bleed your radiators. To do this, our experts recommend following these steps:

  1. Turn off the heating and let the radiators cool down
  2. Use a radiator key to open the valve
  3. Place a bucket underneath the valve to catch the water that comes out
  4. Turn the key and release the trapped air until water drips out - this should bring the pressure down
  5. Check the pressure gauge after releasing some water to see if it's at the right level again

Low boiler pressure

Now, let's talk about the other end of the spectrum - low boiler pressure. If your boiler pressure is too low it can cause your boiler to shut down or not pass hot water around your central heating system. While this is not as serious as high boiler pressure, it can quickly affect your comfort levels, especially during the winter.

Signs your boiler pressure is too low:

  • You have no running hot water
  • Your radiators aren't warming up
  • The pressure gauge has dropped

Causes of low boiler pressure:

Our experts have shared below some of the most common causes of low boiler pressure:

  • Radiator bleeding: When bleeding a radiator to release air and water, it is possible for the boiler pressure to become too low. That's why its essential to keep an eye on the pressure gauge when doing this.
  • Water leaks: Leaks in the boiler system or its components, such as pipes or radiators can lead to water loss and lower pressure
  • Faulty expansion vessel: If the expansion vessel fails to maintain proper pressure, it can lead to low pressure in the boiler

If you feel confident enough and it is safe to do so, you can increase your boiler's pressure. To find out how, see below.

How to fix low boiler pressure

Increasing your boiler's pressure is fairly simple, however it should be attempted with caution. Our experts recommend following these steps to safely increase your boiler pressure:

  1. Turn off your boiler completely
  2. Find the filling loop - this is usually found underneath the boiler with levers either side or a keyed filling loop
  3. Fill the filling loop - turn the valves to align with the braided hose and watch the pressure gauge climb
  4. Stop the valves once it reaches 1-1.5 bars on the pressure gauge
  5. If there are no leaks or faults, your boiler should return to normal.

Our experts recommend letting your boiler run for a few hours afterwards and then check the pressure gauge again. If the pressure has remained steady, you should be in the clear. However, if you suspect a leak or a more serious issue, do not hesitate to contact us, so that we can get one of our qualified engineers out to you ASAP to resolve the problem.

To summarise, understanding and maintaining the correct boiler pressure is essential for the efficiency and safety of your heating system. Whether its dealing with high or low boiler pressure, taking the appropriate steps to address these issues can ensure your home stays warm and comfortable during the winter months. Remember to consult your boiler's manual for specific pressure recommendations and, if needed or for added peace of mind, contact us to speak to one of our boiler experts.

If you're dealing with persistent boiler pressure issues, it could be time for a boiler replacement. Don't fret, new boiler installations are fuss-free with Padly - get an instant quote online and spread the cost with boiler finance. Get a quick quote now.

Spread the cost with Padlys 0% APR finance options

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