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How To Reduce Boiler Pressure ?

The boiler can be referred to as the soul of the central heating system. Practically present in every household these days, any malfunction such as boiler pressure fluctuations in it can lead to further complications which only can be compensated by heavy repair jobs, or sometimes full replacement. Therefore, it’s important to know about your boiler’s functionality and operating method.

One of the most common issues caused in boilers is pressure fluctuations which sometimes go lower, or higher than the required limit, needing to be looked after and fixed in the meantime to avoid certain consequences. Just to save your time, here we will be discussing optimum boiler pressure, causes of high pressure, and how to lower it.

To understand the aforementioned terms, there are some things you need to know first…

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What is boiler pressure?

First things first, boiler pressure should not be confused with pressure related to tap water. It’s actually the balance between water and air in your central heating system. For a boiler to work optimum the boiler pressure should neither be too high nor too low as both can affect its functionality. On one hand, where high pressure overloads your system, low pressure can completely cut it off, each equally unfavorable in its own way! 

What is the optimum boiler pressure?

The pressure should orient around 1-bar at the time when there’s no hot water running in the system or heat isn’t turned on yet. This is actually a low-pressure setting. Once the water starts running, the pressure should be between 1.5 and 2 bars. Even increase up to 2.5 bar is normal when hot water is in use. However, Pressure higher than that is counted as high, therefore needs proper treatment to be normalized. 

What causes High Boiler Pressure?

There are various causes for High Boiler Pressure including faulty and leaky parts, or excessive amounts of water. Although the former reason may require a professional Gas Safe Engineer for which you can consult Serviceteam, the latter one can be easily fixed if you’re a DIY. The most common cause of excessive water is pressure adjustment from a very low level. It usually occurs when the filling loop pumping water to the boiler is left open. Make sure it is fitted well before taking further steps! 

How to Lower Boiler Pressure?

Pressure reading and Safety Valve Check

An effective way of normalizing Boiler pressure is given as follows, in a step-by-step manner for better comprehension. However, you might need a professional for it! 

  • First of all, find the pressure gauge situated on the front-side of the boiler.
  • Check if the pressure is sticking around 3-bars.
  • Look for the safety valve situated on the top. If it is broken or working improperly, it might be the reason for high pressure. 
  • Inspect it for any sort of cracks or steady streams of water. It is important that the valve doesn’t have any cracks or leakage as it will need a good repair job or even a complete replacement in severe cases.

Just in case everything’s alright even after a thorough check, there might be some other issue that can be fixed with simple bleeding:


If you even have the slightest idea of a boiler’s functioning, you can solve boiler pressure issues caused due to an excessive amount of water. The process is pretty straight forward. You will just have to bleed it! 

Here’s the step by step method of doing it: 

  • Buy a radiator key from your local hardware store just in case you don’t have it. 
  • Make sure that the boiler is cold before you proceed. Its a safety precaution often neglected which results in serious burn injuries. 
  • Locate the release valve on your radiator, usually situated on top. Turn it anti-clockwise to release the trapped air.
  • Along with that, you’ll also see water leaking from the radiator. It’s preferable to place a container in a proper position to keep the floor from getting wet.
  • After some time the air and water discharge will stop.

If the problem is minute, it should bring back the boiler pressure to normal.

Other Solutions

In terms of complicated issues, Here are some other possible solutions you need to try:

  • Try closing the valves on the filling as extra water supply might be overloading the boiler, consequently causing high pressure. 
  • Remove the debris by draining some water out of the filter as it might be blocking the water passage, increasing the pressure on the boiler in turn. 
  • If you know about pressure control operating, check if they are working correctly.

If all is good, call a professional to identify the problem.

Need Help?

If you are looking for any sort of boiler repair, replace, and maintenance service throughout London, Contact us straight away at 020 3925 6439. We have highly qualified gas safe engineers along with extremely customer-friendly staff who are ready to help you 24/7. Not only will they hear your questions, but will give you expert advice on tackling the situation. All you need to do is just to dial our landline number and you’ll find us at your doorsteps.


Q: Will the boiler turn off if pressure is too high?

A: If your boiler is properly functional, then yes! It will turn off safely when the pressure reaches up to a considerable level, preventing any major inconvenience. However, it can be dangerous if there are pre-existing faults in the boiler, resulting in an explosion.

Q: What happens if the boiler pressure is too high?

A: The boiler pressure is actually controlled by Expansion Vessel. However, extremely high-pressure accompanied by too much air will result in water coming out of your pressure relief valve. Nothing to be worried about. Simple bleeding will do the job for you. 

Q: How to know if the boiler is going to explode?

A: Here are the major signs that point towards the boiler explosion:

  • Leaking pressure valve. 
  • Popping noises.
  • Brown water.
  • Bad installation.
  • Unpleasant smell.
  • Pressure and temperature fluctuations.

Q: Is 3 bar boiler pressure normal?

A: Pressure up to 2.5 bar is normal. However, more than that can point towards complications in the system that needs to be checked and fixed on immediate measures.

Q: What happens if you bleed a radiator when it is on?

A: Bleeding a radiator while heating is on can be dangerous as it may be too hot to touch. Make sure it is turned off before you bleed it to avoid certain troubles.

Q: How often should you bleed a radiator?

A: A radiator should be bled at least once a year, especially at the start of the season as it will be in heavy use afterward. 

Q: What happens if the radiator isn’t bled regularly?

A; If the radiator isn’t bled on regular bases, the condition will even worsen as it might result in debris and rust build-up, consequently reducing the central heating system’s efficiency. Not only will it cause delayed healing, but comparatively high bills.

Q: Should you be able to hear water running in the radiator?

A: If you hear water dripping or tricking inside the radiator, it’s a clear sign of water pockets being formed inside. Therefore, to get the air out, you must bleed the radiator. It will solve the issue. 

Q: Why is the boiler gurgling?

A: This is also caused by air build-up in some parts of the boiler. Moreover, some blockage or sediment build at the bottom of the boiler can also be the reason. Not to mention the frozen condensate pipe that needs to be thawed. Bleeding is usually an effective method to solve the aforementioned problems. 

Q: Is a noisy boiler dangerous?

A: Any sort of noise including gurgling, banging, or whistling coming out of the boiler points towards air or another material build-up inside the appliance which if not looked after on time can lead to complete boiler breakdown or extremely expensive repairs. So make sure you do something about it before it’s too late! 

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