How to Increase the Water Pressure in Your Boiler

A boiler is an essential part of homes and businesses. It heats spaces and provides hot water in taps and showers. A boiler is essentially connected with radiators through an extensive pipework, which runs across the entire building. In large units, it is an important part of the central heating system. To work perfectly, the boilers need appropriate pressure. Any deviation from the standard pressure results in malfunction, which may end up in a complete shutdown as well. While water pressure lower than the standard level might not pose any serious physical danger, it often results in no heat and an inconsistent hot water supply. 

A higher water pressure, on the other hand, is a seriously dangerous event, as it may end up in the bursting of pipework or water leaks from the boiler itself. That’s why keeping a watch on the water pressure in your boiler is so important. A lower boiler pressure, once or twice in a year, is just a routine matter, whereas a frequent drop in pressure is something that needs immediate attention. In most cases, you can easily raise the boiler pressure yourself, without calling the engineer. However, it is important for you to understand the whole process to avoid any mishandling. 

This blog will guide you through the entire process, so you can easily manage your boiler pressure. 

Understanding Appropriate Water Pressure of a Boiler

When talking about the water pressure, it is crucial for you to be clear on what the standard or appropriate level is for optimum performance of a boiler. The water pressure of a boiler is prominently visible on it in the majority of boilers. Normally, the pressure meter is in the form of a dial with a pointer needle. In this type of pressure meter, the standard level of water pressure is marked green on the dial. In most recent versions of boilers, the pressure meter comes in digital form, giving the exact pressure level displayed in digital numbers. 

In any case, the standard or perfect water pressure should range somewhere between 1 and 1.5 Bars when the radiator is cold. On the other hand, when the radiators are hot, the pressure may rise beyond 2.5 bars or sometimes even up to 2.75 bars. Anything less than or higher than this range is considered abnormal pressure, which needs immediate attention. 

Releasing excessive pressure is usually done through bleeding the radiators or by releasing the pressure through pressure relief valves. In the event of a drop in pressure, below 1 bar, you need to increase the pressure instantly; otherwise, there will be no heating in your building. 

The water pressure of a boiler is directly related to the amount of water present in the boiler system. A reduced pressure simply means that the volume of water in the boiler has decreased. That otherwise means you need to top up the volume of water in your boiler. All boilers are equipped with a proper system to increase water pressure by allowing it to flow into the boiler. 

Reasons For Low Water Pressure in Boilers

Under normal circumstances, a boiler should function flawlessly, without any noticeable pressure drop. Slight deviation in the pressure can occur often, which is just normal. This often happens due to very minute leaks or sometimes due to excessive bleeding of radiators. 

On the other hand, a noticeable low pressure is a sign of some fault in the system, mainly being the excessive water leaks. Here are some major causes of low water pressure in your boiler: 

• With consistent usage of boilers, some parts of the pipework may weaken or rust, which causes leakage. Water leaks are one of the main reasons for dropping the water pressure of a boiler. 
• Sometimes, water may also leak from the internal parts of the boiler. It often remains hidden, as it cannot be detected without opening the boiler’s internal parts. This also results in lowering the pressure. 
• Another reason for low water pressure might be a leak in the radiators, especially the joints and connections of the pipework with them. 
• A faulty pressure relief valve may also cause a reduction of water pressure. It often happens when the pressure relief valve is stuck open due to a fault. In this case, excessive water may escape from the boiler, resulting in low pressure. 
• As a routine matter, you often need to bleed the radiators to release air pockets or higher pressure. It may also result in excess water released from the boiler, which may cause a low pressure. 

Increasing the Water Pressure in Your Boiler

Once you have detected lower pressure in your boiler, the only remedy is to increase the pressure by injecting more water into it. The process is quite simple and often similar for most of the boilers. Most of the newer versions of combi boilers are equipped with a water filling loop, which facilitates topping up the water pressure. Some other boilers come with an internal filling key. 

Step-By-Step Guide on How to Increase Water Pressure in A Combi Boiler, With A Filling Loop

• As a thumb rule, always switch off your boiler before starting any work on it. 
• Before topping up water pressure, turn off the boiler and let it cool for at least one hour. 
• Once the boiler has cooled down, locate the filling loop. A filling loop is a flexible hose pipe with one or two valves, often at both ends of the hose. Sometimes the hose and the valves are integrated into the boiler. It can be found easily, but if you cannot find it, you may refer to the user manual provided by the manufacturer of your boiler. 
• The valves of the filling loop often come with a lever, whereas some of them can be operated with a screwdriver. Whatever the type may be, you need to turn on these valves, one after the other, so that water may enter the boiler system. You can easily hear the sound of water flowing into the boiler. 
• While the water starts entering the system, keep watching the pressure meter. You will notice a slow increase in the water pressure. Allow the water to enter the system until the required water pressure of 1 to 1.5 Bars is achieved. To be on the safe side, try to keep it slightly less than 1.5 bars. 
• Once the pressure reaches the desired level, turn off the valves one after the other. Make sure that the valves are tightly closed so as to completely cut off the water inlet. Always remember that a water inlet valve is open when its lever is aligned along the direction of the pipe. When the lever is at a ninety-degree angle to the direction of the pipe, it is closed. 
• Once the required pressure is achieved and the water inlet valves of the filling loop are tightly closed, you can safely restart the boiler. Usually, it should take around 5 to 10 minutes for the water to get heated. 
• After restarting the boiler, you need to monitor the pressure meter to check whether the pressure remains stable. 
• Under normal circumstances, it should remain stable. If water pressure drops considerably again, it is time to call a Gas Safe registered engineer to thoroughly check and detect the fault. Remember, only a Gas Safe-registered engineer is authorized to work on a gas boiler. 

Step-By-Step Guide on How to Increase Water Pressure In A Combi Boiler, With Filling Key

• Internal filling is clipped inside the boiler. Once located, remove it from the clip. 
• Insert this key in the filling link, which can be found on the right side, in the form of a hole. 
• When fully inserted, turn the key anticlockwise. Then, slowly turn the white square clockwise, which will allow the water into the boiler system. You can hear the sound of water entering the system. 
• Keep watching the pressure meter until the desired pressure of 1 to 1.5 bars is achieved. When the pressure is topped up to the desired level, turn the white square to its original position. Simultaneously, turn the key back to its original position and take it out. 
• Dry off the filling key and put it back into its clip. 
• Turn on the boiler. You may also have to reset the boiler. 
• Monitor the pressure to ensure that it remains stable. 
• If the pressure drops again, you may need to call a Gas Safe-registered engineer to detect and fix the fault. 

Important

• If the pressure keeps dropping, even after the top-up, it is an indication that the boiler needs a thorough inspection. You should now call a Gas Safe-registered engineer to detect the fault. Never try to look for faults inside the boiler yourself. It will be a risky attempt. 
• Never overpressurize your boiler. Anything beyond 2 bars (cold pressure) is considered overpressurizing. Always keep it below 2, preferably around 1.5 bar.
• Make it a routine to monitor water pressure at least once a month. 
• Ensure to conduct an annual servicing of your boiler. 
• Make sure that your boiler is included in the annual gas safety inspection.

Conclusion

Maintaining a perfect water pressure in a boiler is crucial for its optimum performance. A higher pressure may result in damaging the internal parts as well as the bursting of the pipework. It may also cause water leaks. On the other hand, a lower pressure may not be a dangerous proposition, but it results in improper performance of a boiler. In the case of low pressure, you may experience no heat and a lack of hot water in taps and showers. 

An occasional drop in pressure once or twice a year is just normal, but frequent lowering of the water pressure is something more serious. You may try to top up the pressure by following the SOPs, but if the pressure drops again, you need to call the gas safe registered engineer to find the actual problem. Always remember that only a gas safe registered engineer is authorized to work on a gas boiler.