A How to Guide on How to Repressurise a BAXI Boiler

If you’ve recently discovered that your BAXI boiler is acting strangely and displaying the error code E118 or E119, it must be repressurised.

While repressurising a boiler may seem like a task best left to a professional or a Gas Safe registered engineer, you may be surprised to learn that you can do it yourself.

Do All Boilers Need To Be Respressured?

Most boilers must be repressurised once or twice a year because they constantly move hot water around, and some water will eventually escape.

However, if you have an annual service booked with a Gas Safe registered engineer, it might not need one.

Before you learn how to repressurise your BAXI boiler, let’s discuss why it may lose pressure or must be repressurised more frequently than the usual amount.

Why Do Boilers Lose Pressure?

Any boiler (no matter the brand) may lose pressure for various reasons. Most of these reasons are related to changes in weather or wear and tear of the overall heating system infrastructure.

Also, when your BAXI boiler displays error codes E118 or E119, the system pressure has dropped below 0.5 bars and will turn itself off to prevent damage.

If you are seeing these error codes more frequently (for example, four times a year), here are some common causes for a boiler to lose its pressure:

Leaks In The System

A small leak in your heating system’s pipes, radiators, and boiler can cause the pressure to drop. Depending on the size of the leak, this pressure drop can happen instantly or gradually.

Locating a leak can be difficult, as they’re not always visible. They can be located along a hidden pipeline length in a wall or under the flooring.

A good indication that your system has a leak, or leaks, is if you need to top up your boiler’s pressure regularly.

Faulty Pressure Relief Valve

A pressure relief valve is a crucial safety component in any boiler system. Its primary function is to release pressure if there is too much of it.

The valve is designed to open automatically when pressure is too high. But if it is faulty or not working, it could release pressure at inconsistent times, not seal properly, and cause a small leak.

In the worst-case scenario (and very unlikely), it could stop releasing built-up pressure, which can be highly problematic.

Issue With The Expansion Vessel

Your boiler’s expansion vessel is an essential component that helps maintain consistent pressure throughout the central heating.

If the expansion vessel is damaged, your boiler’s pressure will drop, requiring a Gas Safe registered engineer to repair it.

Cold Weather

When the temperature outside drops below freezing for an extended time, your boiler’s external condensate pipes can freeze.

With a BAXI boiler, you will see an error code of either E133 or E28 to indicate this has happened.

But when your condensate pipe freezes, the boiler will shut down or release built-up pressure, lowering the system’s pressure over time.

Loose Joints Or Connections

Over time, your boiler’s system will be subjected to wear and tear. This wear and tear will result in connections and joints becoming loose, creating small leaks.

Your boiler will lose pressure over time, and how quickly it happens depends on the following:

• The health of your overall system
• How often do you use your boiler
• Major temperatures fluctuations

The last cause of low pressure could be due to lousy maintenance.

Bleeding Radiators

Bleeding radiators is a simple task that anyone can do themselves. The main purpose of bleeding a radiator is to release trapped air in the heating system.

DIYers can release too much water with the trapped air when bleeding radiators. Depending on how much water escapes will affect your boiler’s pressure.

If a lot of water escapes, the system’s pressure will drop dramatically, but if you keep it tidy, only a slight pressure adjustment will be needed.

Many of the causes above will require a Gas Safe registered engineer to fix the problem before repressurising your BAXI boiler.

But what is the best pressure level for your BAXI boiler?

What Is The Best Pressure Level For A BAXI Boiler?

Your boiler requires a stable pressure level to operate efficiently.

The best pressure level for most boilers in the UK is between one and 1.5 bars but always refer to your boiler’s manual in case your manufacturer’s recommendation is higher or lower.

Also, a BAXI boiler’s pressure gauge will be displayed on the front of the unit.

Understanding this pressure gauge is simple: all is good if the needle is in the green section. But if the needle is in the red sections, the boiler’s pressure is too high or low.

If you have discovered that your boiler needs to be repressurised and are confident there are no other issues, it’s time to start repressurising your BAXI Boiler.

Step By Step To Repressurising Your BAXI Boiler

When you discover that your boiler’s pressure is too low, or perhaps you’ve been served with the BAXI Boiler error codes E118 or E119, you will want to switch off your boiler and repressurise your system.

Step 1: Turn Off The Power

You can turn off your boiler by the closely located fuse spur (or, for the layman, a big switch). If you can’t find this switch, boilers can also be wired into a standard home socket.

But when in doubt that you haven’t switched off your boiler, turn off all the power in your home from the switchboard.

When you’re confident the power is off, locate your system’s filling loop system.

Step 2: Identify and Find The Filling Loop System

A filling loop system is used to top up the water levels in your boiler’s heating system or to connect your boiler to your home’s cold water mains.

Usually, the filling loop system is located underneath the boiler.

There are two types of filling loop systems: External and Internal.

While there can be some differences in how these systems work, they generally follow the same principles.

External Filling Loop

As the name indicates, these filling loops are located outside your boiler. Usually, the external filling loop is a metal braided hose that connects your main cold water supply to your central heating system.

The external filling loop features two valves. One controls the water flow from the mains, while the other ensures no backflow from the heating system into the mains. A flat-head screwdriver may be required to open and close these valves.

Once you’ve repressurised your boiler, you will remove the external filling loop. If you don’t remove the filling loop, assuming it’ll save you time in the future, don’t.

Leaving an external filling loop attached will increase the chances of contaminating your heating system and lead to sludge build-up, which will require calling in a professional.

Internal Filling Loop

An internal filling loop is integrated into your boiler, common in modern boilers. You will either need a key to unlock it or a lever tap that doesn’t require additional tools to release your internal filling loop.

Internal filling loops are more convenient and can be permanently installed, meaning there is no need to detach and store them away.

Sometimes, the installer will store away a linkage part of your internal filling loop near the boiler. This linkage is called a rigid filling link. Usually, these links are bent copper pipes and come with two brass wing nuts and washers.

Before attaching it, ensure the water mains and central heating boiler taps are securely off. If it is not marked on the system, generally, you want the lever to be positioned in a direction that crosses the pipe.

When attaching the rigid filling link, remove the system’s caps (which are bound to be attached to protect the pipes’ thread), place the washer in position, and slowly tighten the wing nuts into place.

Don’t force the wing nut to take; doing so will damage the thread and cause the rigid filling link to leak.

Now that your filling loop is in place, it’s time for the next step.

Step 3: Opening The Valves

As we mentioned, both filling loop systems have two valves to ensure that the water from the mains flows in one direction.

Open the first valve, allowing cold water from the mains to fill the loop. When ready, gently open the second valve to the boiler’s heating system. Don’t open the valve all the way, as this will fill up the system too quickly, overpressurising it.

Allow the water to flow into the system slowly. At the same time, you must keep an eye on the boiler’s pressure gauge.

You should see the needle start to rise. Wait for the needle to move to the green area on the gauge, and close off the second when happy with the pressure level.

Your BAXI boiler’s manual will indicate the perfect level to repressurise your boiler, which is around 1 to 1.5 bars and a little more. For example, you might want to add an additional 0.1 bars to ensure that if slippages occur, the pressure drops below the optimal level.

Step 4: Closing The Valves

As mentioned, when the correct pressure is achieved, you will close off the valve to the boiler’s heating system.

The next valve to close is the water mains valve. Make sure that the valves are correctly closed. If they aren’t, you will notice the pressure in your system continues to rise.

You must remove the external filling loop for those who have attached it. Make sure to have a towel or bowl to catch the water in the pipe.

Step 5: Turn It Back On

If everything has gone smoothly, it is time to turn the BAXI boiler back on. After turning the boiler on, monitor the pressure level to ensure it stays within the acceptable range.

You will need to take an additional step for those who have accidentally added too much water.

Step 6: Draining Excess Water

To lower the pressure in your boiler system, you will need to locate your radiator’s key or a flat-head screwdriver.

This will be familiar to those who have bled their radiators before. However, you will need an additional person to monitor the boiler’s pressure gauge to tell you it is at the desired level.

But for those who haven’t done so before, you will need to do the following:

Find The Bleed Valve

Most bleed valves are located at the top of the radiator, but they can be on either side (left or right).

Usually, a bleed valve will look like a small metal square, or depending on the manufacturer and your opinion, it could look like a screw located with a hexagon nut surrounding it.

If you are in doubt, most radiator companies publish an online manual for their product for you to double-check.

Bleed The Radiator

Insert your radiator key, or use your flat-head screwdriver, and turn it in an anti-clockwise direction. Make sure to loosen the valve slowly, as a quarter rotation is often enough to release the water in the radiator.

Make sure to have a container to catch the water. Close the bleed valve when the pressure reaches the correct level. Hopefully, that extra person monitoring the pressure gauge informs you quickly.

If you accidentally drain too much water again, you can repeat the filling process or call a professional for help.

Call WarmZilla To Help You

While it is noble to learn a new skill, sometimes it’s best to call a professional for help. WarmZilla offers emergency boiler repair services within 48 hours anywhere in the UK.

Feel free to talk to one of our many experts. They can advise you on the next best step.