A How To Guide On How To Repressurise An ATAG Boiler

However, if you have an annual boiler service done by a Gas Safe registered engineer, you might not need to top up your boiler’s water level.

We said the 118 error code could indicate that you must repressurise your boiler. There are various reasons why a boiler’s pressure can drop.

Also, if you frequently top up your water levels, you may need the help of a Gas Safe registered engineer.

Reasons Why Your ATAG Boiler Is Losing Pressure Regularly

No matter the boiler brand in your home most will lose some pressure over time because of general use. However, the amount of water lost due to regular use is minimal.

But even a tiny leak can cause your boiler to stop working due to a loss in pressure. There are several common causes for a boiler to lose pressure regularly, but the most common is a leak.

A Leak In The System

As mentioned, a tiny leak will result in a pressure drop that could stop your boiler from working. Generally, a pressure drop from 1.5 to 0.5 bars would mean a loss of three litres.

For a leak to drain three litres of water within a week, it would need to lose 17ml an hour. When you consider that a tablespoon is only 15ml, it is a tiny leak.

Locating a leak/s can be difficult, as they are sometimes not visible. Leaks can be located anywhere along the system’s pipelines, such as inside a wall, under the floor, or in the ceiling.

Telltale signs that your boiler’s heating system has a leak/s include:

• Visible water or damp spots
• Inconsistent heating or hot water
• Strange noises (gurgling or hissing)
• Unexplained increase in water usage
• And unusual smells (dampness or wet metal smell)

A Gas Safe registered engineer can help locate difficult leaks within a heating system. If an engineer is looking at your system, ask them to do the next task.

Not Enough Inhibitors

Your home’s boiler needs inhibitors to prevent and slow down chemical reactions. Otherwise, newly developed compounds can cause blockages, which result in sludge and will lower your boiler’s pressure level.

One chemical reaction that develops and contributes to sludge and air pockets is when water reacts with the system’s radiators, creating rust. The byproducts of this reaction are air bubbles and rust particles.

Air bubbles, or gas, must be released from radiators to allow water to circulate around your heating system and maintain a stable pressure level.

You can bleed your radiators to alleviate air pocket blockages, which is a simple DIY task.

However, if you regularly top up your boiler’s system, the inhibitors that prevent these chemical reactions become diluted. By diluting these inhibitors, you create a heating system environment where sludge will develop more quickly.

Contact a Gas Safe registered engineer if you want to correct your system’s inhibitor levels.

Bleeding Radiators Incorrectly

As mentioned, bleeding your home’s radiator is a simple task.

Bleeding your radiators releases air pockets from your home’s heating system. These air pockets can cause blockages, so releasing them allows your boiler to distribute heat evenly around the house.

A sign that you have an air pocket in your heating system is If there are cold spots on the top of your radiators. If this is the case, you will need to bleed your radiators.

However, we can all make mistakes, and if you do so when bleeding your radiators, you can accidentally reduce your boiler’s pressure.

When bleeding your radiators, you usually want to release the trapped air bubbles gradually. However, if you accidentally open the valve too far and allow too much water out of the system, you will need to repressurise your boiler.

Boiler Pump Issues

The pump in your boiler plays a vital role in circulating water throughout the heating system and maintaining its pressure. Setting your boiler’s pump correctly can save you significant time and hassle.

If the pump is set to a high speed, it may create air bubbles in the water, leading to air pocket problems.

During an annual service, a Gas Safe-registered engineer will adjust the boiler pump as needed. However, if the pump is broken, it will struggle to maintain the heating system’s pressure.

Signs of a broken pump include it feeling extremely hot, water leaking, or cold water flowing through it.

If the pump is damaged, you’ll need a Gas Safe-registered engineer to replace it.

Expansion Vessel Issues

A boiler operates as a closed and pressurised system that circulates warm water. This means your heating system requires components that can withstand the expansion and contraction caused by temperature changes.

These temperature shifts cause minor pressure fluctuations, which are managed by the boiler’s expansion vessel. The expansion vessel’s tank contains a rubber diaphragm that inflates and deflates to maintain balance.

The diaphragm works alongside an air cushion to regulate the system’s internal water pressure. When the water heats up and expands, the diaphragm is pushed toward the air cushion. The diaphragm returns to its original position when the water cools and contracts.

The diaphragm and air cushion prevent sudden pressure spikes that could damage the heating system.

If the expansion vessel malfunctions, becomes damaged or loses its air charge, it can no longer maintain the pressure balance, resulting in a system pressure drop.

In such cases, you’ll need to contact a Gas Safe-registered engineer to repair or replace the expansion vessel.

Chilly Weather

When temperatures drop below freezing for an extended period, the external condensate pipes of your boiler may freeze.

If your ATAG boiler has a frozen condensate pipe, it might display error codes 133 or 501.

Error code 133 indicates that your boiler’s pilot light has failed to ignite after five attempts.

Error code 501 means there’s no flame after five attempts.

Your ATAG boiler does this as a safety feature. It would be dangerous to start your unit if there was no method to dispose of the toxic byproducts by the condensate pipe.

You can tell your boiler’s condensate pipe has frozen via the following signs:

• An unusual gurgling noise
• Water dripping beneath the boiler
• The boiler shutting off
• No hot water or heating

Best Pressure Level For An ATAG Boiler?

Your boiler must maintain the correct pressure level to perform efficiently.

The best pressure level for most boilers in the UK is between 1 and 1.5 bars.

However, as mentioned, ATAG says their boilers should have a pressure level of around 1 to 1.2 bars when cold and between 1.8 to 2.4 bars when working.

To check your ATEG Boiler’s pressure, its users can use one of two methods:

• The analogue gauge (which has a needle) is located at the bottom of the unit on the left-hand side.
• Or via the digital display panel. To view the level, hold the Eco button for 6 seconds and then scroll through the menu with the plus button (+) until you see “A6,” when left, it will display the water pressure in the system.

Step-By-Step To Repressuring Your ATAG Boiler

While repressurising your ATAG Boiler is simple, it is essential to follow these instructions closely.

As with any project, it’s essential to prioritise safety.

Step 1: Turn Off The Power

Turning off your boiler’s power is usually straightforward. You simply flip a switch, known as a fused spur, which resembles a large, square light switch.

If you cannot locate this specific switch, note that some boilers may be wired into standard household sockets.

For ATAG boilers, the manufacturer also recommends that boiler clocks and room thermostats for heating or hot water controls are turned off.

If you’re unsure whether you’ve successfully turned off the boiler, it’s best to switch off all power in your home at the main switchboard.

Additionally, some manufacturers recommend allowing the system to cool down for 4 to 6 hours before repressurising it.

Step 2: Identify And Locate The Filling Loop System

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

The filling loop is typically found beneath the boiler and comes in two types: external and internal.

While they differ in design, both perform the same function.

External Filling Loop

An external filling loop is usually a braided metal hose that links the main cold water supply to the central heating system. With ATAG boilers, the iS range uses an external filling loop. These loops are often stored near the boiler.

An external filling loop has two valves:

1. Water Flow Valve — Controls the flow of water from the mains.
2. Backflow Prevention Valve — Stops water from the heating system from flowing back into the mains.

Depending on the design, you may need a flat-head screwdriver to operate the valves. In some cases, levers, additional keys, or tools might be required instead.

Important: Always remove the external filling loop once you’ve repressurised your boiler. Leaving it attached can increase the risk of contamination.

External filling loops are more common in older boiler models.

Internal Filling Loop

An internal filling loop is integrated into the boiler and is usually standard in modern systems. It is more convenient as it remains permanently installed and is easier to use.

Some internal filling loops may require a key for operation, while others use lever taps. These systems might also feature a rigid filling link, a bent copper pipe with brass wing nuts and washers.

ATAG’s iC and iC Economiser Plus models use a rigid filling link in a ‘U’ shape.

Steps to Attach a Rigid Filling Link:

1. Ensure both the water mains and boiler taps are turned off. The lever should be at a 90-degree angle to the water flow.
2. Remove the blanking caps that protect the threads and outlets from debris.
3. Position the washers inside the wing nuts and carefully tighten the rigid filling link into place. Avoid over-tightening to prevent damage to the threads and leaks.

Once the filling link is securely in place, you’re ready to proceed to the next step in repressurising the boiler.

Step 3: Opening And Closing The Valves

When filling your ATAG boiler, the taps should be gently opened to a quarter of their turn—the first valve to allow cold water from the mains to flow into the filling loop. You should hear the water entering.

Slowly open the second valve to the boiler’s heating system gently. Avoid fully opening it, as this could overfill the system and cause overpressure.

Allow water to flow gradually into the system while closely monitoring the boiler’s pressure gauge.

You will see the gauge rise to between 1 and 1.2 bars of pressure. Once the needle on the gauge reaches this desired level, immediately close both valves to stop the water flow.

If you monitor via the digital screen, error code 118 will stop, and the boiler will be ready to operate. However, if the error code is still displaying, you should fill up the system a bit more, but not over 1.4 bars.

When the correct pressure level has been reached, the display will show ‘OK’, and the boiler should be ready to use.

If you’ve had to attach an external filling loop, remove it carefully and have a bowl or towel ready to catch any water that may escape.

In case you’ve accidentally overfilled your ATAG boiler, you’ll need to bleed your radiators to bring the pressure back to the correct level. As mentioned earlier, this is a straightforward task.

However, if you’d rather not take on another DIY project, you can always call a professional for assistance.

Call WarmZilla To Help You

While learning a new skill is admirable, sometimes time constraints or the need for precision make it better to rely on a professional.

WarmZilla provides emergency boiler repair services within 48 hours across the UK.

Our team of experts is here to help. Contact us for advice on your next steps or to schedule a professional visit.