How to Repressurise a Worcester Bosch Boiler

But you can quickly fix this issue yourself by repressurising the system.

Now, let’s discuss what the best pressure level is for your Worcester Bosch boiler?

Best Pressure Level For A Worcester Bosch Boiler?

All boilers need to maintain 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 this being said, always refer to your boiler’s manual if your manufacturer’s recommendation is higher or lower.

With Worcester Bosch, they have released to the public a system-filling guide and have said their boilers work best between 1 to 1.5 bars.

Also, in this guide, Worcester Bosch explains in detail how to read their pressure gauge, which is located on the front of the boiler.

To summarise their guide, your boiler will work efficiently if the needle is in the green zone. If it is in the red zone, your boiler will most likely shut down.

The Worcester Bosch guide also states that:

“It is advised that should the system need refilling on a very regular basis, a plumber should be called to check for leaks in pipes or, more likely, radiator valves.”

But if you’re sure your boiler just needs to be repressurised, here’s our step-by-step process.

Step By Step To Repressurising Your Worcester Bosch Boiler

Now that you’re ready to repressurise your Worcester Bosch boiler, you will want to follow our step-by-step closely.

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 some differences exist 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, which is common in modern boilers. You will either need a key to unlock it, or your internal filling loop will have a lever tap that doesn’t require additional tools.

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 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 blanking caps (which help keep the thread intact and prevent debris from gathering in the outlet), position the washer, 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 monitor 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.

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.

For those who have repressurised their Worcester Bosch boiler with an external filling loop, you will need to remove it.

When removing the external filling loop, 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 Worcester Bosch 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 another 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.