Why Does My Boiler Keep Losing Pressure


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Boilers are an essential part of any central heating system, providing us with hot water and warmth during the colder months. However, one common issue that many homeowners face is a boiler losing pressure. 

If your boiler pressure keeps dropping, it can be frustrating and can impact the efficiency of your heating system. In this blog, we will explore the causes of boiler pressure loss, how to recognize it, and what steps you can take to fix the problem.

How Boiler Pressure Works

To figure out why your boiler is losing pressure all the time, you need to know how pressure works in a boiler. If you have central heating, the water pressure inside is called boiler pressure. Maintaining the flow of hot water is important for keeping the heating system working right. 

The pressure release valve helps keep the pressure in the boiler from getting too high and causing damage. The expansion tank is also very important because it protects the whole system from damage by taking in extra air.

The Function of Boiler Pressure

For central heating to work, the boiler must have enough air. It makes sure that your boiler works well so that it can heat your home and give you hot water. Boiler pressure release valves bring it down to a safe level. It lets go of pressure when it gets too high, which protects the central heating system. The expansion tank, on the other hand, takes in extra air, especially when warm water expands. This keeps the air steady, which makes sure the boiler is safe and works well.

The boiler pressure affects how well a central heating system works. If the pressure is too low, the system might not be able to heat or heat the water enough, which could make the home uncomfortable. But high pressure could put stress on the system, which could lead to leaks or the boiler breaking down. The right pressure is important for the safety and efficiency of a boiler.

Importance of Maintaining Optimal Boiler Pressure

High Pressure Means Better Heating

Keeping the boiler pressure at the right level is important for the heating system to work well. How comfy your home is will depend on the pressure level of your hybrid boiler or traditional heating system with hot water tanks.

Minimize Heating Problems

Keeping the pressure in the boiler system within the range given may stop heating problems. A drop in pressure can make radiators cold, hot water supply problems happen, and the heating system works less efficiently. Keeping an eye on the pressure gauge and making sure it stays in the right range will help you find pressure loss early and stop problems before they happen.

Saves Your Money

Checking the pressure levels keeps the heater working efficiently and could save you a lot of money on fixes. Finding pressure loss lets you get to the bottom of the problem quickly and stop it from getting worse

High Pressure Enhance Boiler Durability

Keeping the air in your boiler at the right level may also help it last longer. High pressure puts stress on the system, which leads to more leaks and other issues. Low pressure could make it harder to get hot water and heat. If you keep the pressure at the right amount, your boiler system may last longer and not need to be replaced or serviced as often.

Another safety step is to check the boiler pressure. The pressure release button keeps dangerously high pressure from building up. As needed to keep the system from breaking, pressure is let out. Safety is very important, and keeping the pressure in your boiler system up is a key part of keeping your home safe.

How to Determine Your Boiler's Pressure

You can figure out your boiler’s pressure by knowing the normal range of pressures. The pressure range is different for each type of boiler, but 1–1.5 bar is the norm. The boiler’s user manual might tell you what the normal pressure range is. The pressure gauge on the boiler should also be checked often. In this way, you can keep track of changes in pressure and find problems.

Recognizing Normal Boiler Pressure Range

For a combi boiler to work well, the pressure must stay in the right range. The best range for central heating and hot water is usually between 1 and 1.5 bar. See the user manual for your new stove to find out what the pressure range is. If you check the pressure gauge every so often, you can see if anything has changed and act quickly to keep it working well.

Detecting Low Boiler Pressure

Low steam flow makes central heating less warm and efficient. Low pressure can be seen in heaters that are cold and water that isn’t hot enough. To keep things from getting worse, this problem needs to be found quickly. Your boiler may not have enough pressure if the gauge shows less than 1 bar. Regularly checking the pressure gauge can help you find low boiler pressure before it gets worse.

Identifying Causes for Boiler Losing Pressure

Internal Boiler Leaks

Detecting internal boiler leaks is crucial. Look for water around the boiler or pipes, and listen for unusual hissing sounds. Additionally, check the pressure relief valve for any signs of leakage.

Faulty Pressure Relief Valve or Expansion Vessel

A faulty pressure relief valve or expansion vessel may lead to pressure loss. Ensure the valve is releasing water at the correct pressure and that the expansion vessel is functioning properly.

Internal Boiler Leaks

It is very important to know that internal boiler leaks can lower pressure without leaving water stains. It might be hard for someone who knows what they’re doing to figure out why the boiler is losing steam because of leaks inside. Wet spots, rust marks, and water around the system could be signs that the boiler is leaking. Leaks inside the system can lower pressure and make the central heating less effective, so they need to be fixed right away.

Faulty Pressure Relief Valve or Expansion Vessel

If a boiler’s pressure drops, the pressure release valve and expansion tank need to be checked. If the release valve or expansion tank isn’t working right, the pressure could change quickly or in strange ways. To find problems early, these parts must be checked on a regular basis. Keep in mind that a broken release valve can lead to pressure loss even if there are no leaks. To get the pressure back to normal, it is important to find and fix problems with the release valve and vessel.

Issues with Recently Bled Radiators

If there are problems, the boiler pressure could drop quickly after the pipes have been bled. Pressure loss could be caused by air that is still in the central heating system after bleeding. To keep the pressure steady, air vents must be tightly shut. If you notice pressure loss after a radiator leak, you need to act quickly to avoid problems. Cleaning radiators that have just been bled may help keep the boiler pressure stable and the central heating system running smoothly.

Damaged Boiler Components

You can stop air loss in the central heating system by checking the expansion tank. If the pressure release valve is broken, the pressure may drop. Rust, wet spots, and water stains may be signs that your boiler is leaking. Air openings are important because they change pressure. By reading a modern boiler guide, you can learn about the system’s parts and make sure they work well and last a long time.

How to Locate a Leak in Your Heating System

If you think your central heating system is leaking, look for water that you can see. The refill loop on a hybrid boiler may also help you find the leak by making the pressure go up. If you can’t find the leak, you should call a Gas Safe professional, especially if it stays even after you fill up the system.

Visual Inspection Techniques

As you look over the boiler system, check the pipes, valves and vents for leaks. Look for rust or rusting on the boiler and its parts. Check to see if the air release valve works and see if the expansion tank is broken or full. Make certain that the air pressure is correct. You might want to get in touch with a professional expert for a more thorough check and analysis.

Professional Leak Detection Methods

There are a number of professional tools that can be used to find and fix boiler leaks. Some of these steps are trying the pressure to find leaks, looking at the pipes and joints visually, and checking the expansion tank. Thermal photography can find leaks that are hidden. If your central heating system breaks, the best thing to do is to call a plumber to look at it and fix it.

Can a Boiler Lose Pressure Without a Leak?

Pressure can drop in boilers without them leaking. There are many reasons why boiler pressure drops aren’t caused by leaks. When parts of the boiler break, like the pressure release valve or expansion tank, the pressure drops. If these parts need to be fixed or inspected, a trained worker should do it.

Non-Leak Related Pressure Loss

The loss of air in the boiler might not be caused by a leak. Problems with the expansion tank, poor pressure release valves, or air in the system can all cause pressure loss. Pressure loss can also be caused by a broken pressure gauge or a system that isn’t working right. 

These worries about things that don’t leak could affect how well the combi boiler and central heating system work. A skilled and alert worker can spot these kinds of problems and make sure the system is well taken care of by repairing the boiler on a frequent basis.

Boiler Component Malfunctions

If a boiler part fails, the pressure in the central heating system could drop. It could be because of lines that are leaking or a pressure release valve that isn’t working right. Pressure drops can also be caused by expansion tanks that are rusting or pressure monitors that are broken. If air gets stuck in the system, the radiators may need to be bled. These problems need to be fixed right away for the central heating system to be safe and work well.

Steps to Fix Low Boiler Pressure

When dealing with low boiler pressure, first place is to check for any visible signs of water leakage in the central heating system. Use the filling loop to re-pressurize the combi boiler to the recommended levels. If you’re unsure about this process, it’s good news that a Gas Safe engineer can assist you. 

Regular maintenance and a boiler service can prevent such issues and ensure the safe functioning of your new boiler. Remember, always hire a certified professional for any boiler installation or repair tasks.

Self-Repair Tips for Minor Issues

In case of minor issues, you can try repressurising a combi boiler using the filling loop. If your boiler keeps losing pressure, check for leaks in the central heating system. Additionally, bleeding radiators and checking the expansion vessel could help. Always ensure safety by following manufacturer guidelines. 

However, for major problems, it’s best to call in a safe engineer for a boiler service. The good news is that with timely maintenance and self-repair, you can avoid the cold water and ensure that your new boiler functions smoothly.

When to Call a Certified Engineer

If your boiler keeps losing pressure, it’s time to call a certified engineer. A safe engineer will assess the central heating system and determine the cause of the problem. If you have a new boiler installation, a good news is that most boiler companies offer credit through a panel of lenders. In such cases, the financial conduct authority regulates the minimum spend and amount of credit. So, when you encounter such issues with parts of the system, don’t hesitate to seek professional help.

Preventing Further Pressure Loss in Your Boiler

By keeping up with boiler maintenance, you can keep your central heating system running smoothly. Modern boilers, especially hybrid boilers, keep the air steady, which is good for houses. Pressure release valves keep pressure from escaping, but if they don’t work right, they can lower boiler pressure. To keep a system in good shape, you need to find and fix things that cause pressure loss, like a filling loop that isn’t working right or boiler service issues.

Regular Maintenance and Inspections

Regular upkeep and checks are needed to keep the pressure in the central heating system from dropping. Finding water leaks and rust spots can help you keep the pressure up. You can keep the boiler’s pressure steady if you know how to use the expansion tank and pressure release button. It might save you time and money to know how much it costs to fix a boiler leak and how much pressure is lost.

Is Regular Pressure Drop Normal in Boilers?

Understanding the natural fluctuations in boiler pressure is essential. Safety devices regulate pressure levels, but it’s important to differentiate between normal pressure loss and potential issues. Factors like the heating system and water pressure can impact boiler pressure. Additionally, consider how boiler pressure affects energy bills in detached homes.


To keep your boiler working well and safely, you need to know and keep its ideal pressure. Figuring out why the boiler is losing power is very important for keeping problems from happening in the future. Common reasons are pressure release valve failure, internal leaks, and radiators that have been bled. 

Find and fix heating system leaks fast by looking or getting help from a professional. It’s normal for boilers to lose some pressure, but if it happens often or with other issues, you should talk to a trained professional. Regular upkeep and checks are needed to keep the pressure up and the boiler’s life long.