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Winter Weather Advice: How to repressurise your boiler

Before you turn your heating back on again after the summer, it is essential that your boiler is operating efficiently in preparation for the winter season. This will give you peace of mind that your heating and hot water is ticking along nicely, ensuring your home is nice and warm for the cold months ahead.

In the guide, we’ll take you through the steps on how to repressurise your boiler so you’re ready for winter.

When turning your heating back on, you may notice that you have low boiler pressure. This can affect your whole central heating system as your radiators may struggle to heat your home properly and water.

Low boiler pressure can be caused by water leaks or excessively bleeding your radiators. As a safety precaution, your boiler may switch off completely which will leave you without heating and hot water.

Check your boiler pressure

If you’re unsure whether or not your boiler needs repressurising, the first thing to do is check your gas boiler’s pressure. The typical boiler pressure is between 1 - 1.5 bars. If it is lower than this, it is highly likely that you will need to repressurise your boiler.

Depending on the model of boiler you have in your home, your boiler’s pressure should be displayed on the front of the boiler interface. You will find either a physical or digital pressure gauge. The dial (or bar) will tell you the level of pressure in the system.

If you notice that the boiler pressure has significantly dropped, it could be that a leak in the system has occurred. Check your boiler systems for any signs of water leaking and call a gas safe heating registered engineer as soon as possible to fix the problem.

How to repressurise your boiler

Repressurising your boiler is something that you can do yourself that doesn’t require a gas safe registered engineer. However, if you do require some help make sure to contact your installer who will be happy to help.

Before starting the process, check your boiler manual. Depending on the make and model of your boiler, there may be additional steps to follow to ensure you repressurise your boiler correctly and safely. However, here are some general instructions for you to follow:

It’s important that your entire heating system is fully switched off. Leave your system to cool before you carry out the next step.

This is a silver connection between the mains and primary central heating circuit. One end will have a handle valve while the other end will have an isolation valve. Sometimes, the filling loop can leak which can cause the boiler to lose pressure so it’s important that both are properly attached at both ends

It’s important that the line on the valve is directly in line with the pipe. If you have a flat head screwdriver, this would be a good tool to use for this.

This enables water to flow smoothly in the system, restoring balanced pressure levels.

As you do this, you should notice the gauge increase as you open the handle valve. Stop once it reaches the recommended pressure level for your boiler.

Do the opposite and turn the handle valve clockwise first and then turn the isolation valve clockwise.

Check the pressure gauge to see if it has gone back up to the normal level. If it has, your boiler should be working again.

How to repressurise a boiler without a filling loop

Some boilers don’t always have a filling loop; this is usually the case for older models of combi boilers. This means that you may have a filling key instead of a filling loop. If you’re unsure, check your boiler manual.

Here are the steps for repressurising a boiler without a filling loop:

1. Turn off your boiler and wait for the whole heating system to cool down.

2. Insert the filling key into the keyhole to unlock it.

3. Turn the valve next to the key until water flows through it. We recommend that you use either a spanner or wrench to do this.

4. Keep checking the valve until it reaches the recommended level for your boiler.

5. Close the valve and turn your heating system back on.

My boiler’s pressure has dropped again, what do I do now?

If you have followed the steps and your boiler’s pressure has immediately dropped again, there could be another issue. A rapid drop in boiler pressure can be linked to a major water leak or a problem with the pressure release valve.

Contact your local heating engineer as quickly as possible as if the leak gets worse it has the potential to cause further damage to your boiler and your whole heating system which could be costly to repair.

Need help repressurising your boiler?