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How to Reduce Boiler Pressure

how to reduce boiler pressure

Every household should have a central heating system, and yours is probably no exception. However, you’re also more than likely to pay it no mind until something goes wrong.

With boilers, the two most common issues involve too high and too low boiler pressure. If you want your unit to operate correctly, you need to know how to deal with these problems whenever they arise.

In this article, you’ll learn how to reduce boiler pressure.

Even if you know nothing about boilers, rest assured – it’s easy!

Read on, and you’ll find out how to check boiler pressure and what to do when the pressure is too high.

Normal Boiler Pressure

Ideally, the pressure inside your boiler should read between 1 and 2 bar. However, there are different boiler models, so you should check the manual to see what range is optimal for your unit.

If there are some issues with the pressure, your boiler will stop working correctly. It may be up and running for a while but if you leave it unchecked, you risk total boiler failure. And when that happens, your only solution might be to get a new boiler.

Checking Boiler Pressure

To determine whether there’s something wrong with your boiler system, you need to check the pressure first.

To do that, find a pressure gauge first. Your boiler model might have a gauge with an analogue (pointer) display or a digital display.

The first one looks like a speedometer or a clock face, with the pointer indicating the pressure. If the pressure’s right, the pointer should be in the green zone, and if it’s too low or to high, it will move towards either end of the scale.

Newer boilers may be equipped with a digital display, which can be an LCD, LED or screen type.

It can also show other information such as temperature or time. In the case of increased pressure, you may see an error message on the display, or you’ll see a flashing pressure reading with a warning.

When Boiler Pressure Is Too High

If your boiler pressure is too high, you’ll notice the following signs:

  • The system may shut down completely
  • The pressure gauge dial is in the red zone or is visibly increased

There may be several reasons why boiler pressure can be too high:

  • You may have accidentally over-pressurised the boiler.
  • Your filling valves may not be shut or screwed tight enough.
  • You may have left filling valves open by accident.
  • If it happens randomly, there may be some issue with your heating system.
  • There’s an excessive amount of water in the system.

Additionally, even in the case of new boilers, pressure issues may be caused by faulty boiler components.

If you’re not a qualified engineer, you’re unlikely to determine the real cause, and you won’t have the skills to replace certain parts.

So, if your boiler doesn’t function properly due to some faulty parts, contact a professional to do some boiler repairs or install a new boiler.

How to Reduce Boiler Pressure

If you want to reduce your boiler’s pressure, follow this step by step guide:

  1. Turn off the boiler.

  2. Make sure that the filling loop valves are fully closed.

  3. Wait for the system to cool down.

  4. Bleed each of the radiators to release the pressure.

  5. Check the pressure gauge when you’re done with every radiator.

    If the pressure hasn’t dropped, bleed one or more radiators once again.

  6. Keep checking the boiler’s pressure gauge.

    If it’s in the green zone or reads about 1.2 bar, you’ve managed to successfully reduce boiler pressure.

  7. In case the pressure is too low, follow the steps to increase it.

  8. Close off the filler valves when you’re done.

How to Bleed Your Radiators

Above, you can read about the general process of reducing high boiler pressure.

How exactly can you bleed your radiators? You’ll find out below:

  1. Purchase a radiator key or look for it if you own one already.

  2. Make sure that your boiler is cold before you start bleeding it.

  3. Prepare a small container and a cloth or a towel to avoid wetting the floor.

  4. Find the release valve on your radiator – it should be located on the top of the unit.

  5. Slowly turn the valve with a radiator key to release the excess air.

    Have a container and a towel ready because the water may start leaking as well.

  6. Check the pressure gauge and observe.

    The process will be complete when the pressure returns to its optimal range.

When Bleeding the Radiators Won’t Help

You’ve bled the radiators and boiler pressure keeps rising or is still too high.

It’s a sign that there may be something wrong with your boiler. For example, the water pressure gauge may be at fault, or you may have issues with other internal components, such as the expansion vessel.

In this case, you should contact a boiler engineer who would determine what the problem is and apply the right solution.

Is High Boiler Pressure Dangerous?

You may be concerned for your safety when you see that boiler pressure gauge in the red zone.

There’s no need to worry since most boilers have a pressure release valve – it releases water when the system is under pressure.

Be careful, though – the water might be extremely hot, so don’t forget about safety measures when you’re bleeding the radiators. However, the situation in itself is not dangerous.

If, for some reason, you can’t fix the issue and the high pressure shuts down your boiler time and time again, get in touch with a heating engineer.

The Bottom Line

As you can see, reducing boiler pressure is very easy.

You just have to know how to check boiler pressure and what steps to follow when something’s not right. You don’t have to be an engineer to deal with high boiler pressure and other heating system-related issues.

However, keep in mind that sometimes it’s better to contact a Gas Safe registered engineer.

Some tasks should be performed by professionals, and only experts can correctly determine what’s the reason behind certain issues.

Additionally, they have the equipment necessary to perform their job safely and efficiently.



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