What Should My Boiler Pressure Be?

Pressure gauge

Your boiler is an incredibly important appliance in your household; however, since it is often locked away in a cupboard, its maintenance is easy to forget about. Boilers supply households with both hot water and central heating, both of which are crucial for our comfort. These appliances make sure that you can have your shower to wake you up in the morning, that you can sanitise your dishes, and that your radiators keep the temperature right when the weather is cold outside.

The pressure on your boiler’s gauge should be between 1 and 1.5 bars when you have the central heating in the off position. The needle on the pressure gauge should not be in the areas marked red. If it is, your pressure will either be too high or too low.

Although boilers should only be maintained by properly trained and certified gas engineers, it is still important that you do your part and regularly check the pressure gauge on the front of this appliance. If the pressure is in a red zone indicating that it is either too high or low, there is something wrong and it is important that you contact a professional to identify and fix the problem.

How does my boiler work?

Gas boilers supply your house with hot water by circulating water in pipework over a series of gas flames. Just like a pan over the hob, as the water passes over the flames it is heated up. This water is used to heat up your house through a central heating system and provide you with your primary source of hot water, to use for things like baths and washing clothes and dishes.

Boilers are also built with pressure relief vales which helps them safely and quickly control jumps in pressure. This pressure relief valve means that your boiler is equipped to run the central heating of your housing in addition to your hot water simultaneously.

If your boiler’s pressure is too high or low, it will most likely shut down completely as a safety precaution. If this happens, call a plumber with a gas engineering license to examine and fix your boiler.

Why does the boiler pressure increase when the boiler is on?

When your boiler turns on and begins heating water within the appliance, the water expands within the central heating system, causing increased pressure. When your boiler is off, the pressure should be low; however, when turned on you should notice a gradual increase on the pressure gauge.

Why do I have low boiler pressure?

You might notice your taps failing to get hot water or your radiators not getting hot enough sometimes. If this happens, it is important to check your boiler pressure because your boiler may have stopped working as the pressure is too low. There are a few reasons why the pressure in your boiler might be low. First, this might mean that there is a leak in your water system. Even if this leak is small and initially unnoticeable, it is still likely that it has led to a gradual reduction in pressure in your boiler. Check around your pipes, radiators, and your boiler to see if there is any dampness. If there is, it’s best to call a plumber who is a registered gas engineer. They will be able to fix the leak in addition to assessing your boiler.

Your boiler pressure might drop when you bleed your radiators. This procedure takes hot water out of your central system, ultimately lowering your pressure. In this instance there is nothing to be concerned about, and the pressure of the boiler will likely return to normal within a few hours.

How do I check the pressure of my boiler?

Checking the pressure of your boiler should be a simple process. Most modern boilers have a water pressure gauge on the front of the appliance. If you have a hydraulic gauge, there will be a needle indicating low and high pressure levels within red sections. If you have a digital gauge, there will usually be a flashing pressure reading warning you that there is low or high pressure in your boiler. 

How often should I check my boiler pressure?

It is important that you check your boiler pressure once a month to make sure that it is not too high or low. You should check the pressure a few hours after bleeding your radiators, because although the pressure will most likely drop you will want to ensure that the pressure hasn’t stayed low. Finally, before you start using your central heating system in the autumn or winter, it is useful to double check your boiler pressure. The last thing you want is for your family to endure a few days of no central heating in the winter because your boiler was overworked.

Your boiler’s pressure should not be something you’re afraid of checking. In most instances, problems that arise have an obvious explanation and are easily fixed. However, if you have any concerns about the condition of your boiler, it is always advisable to contact a registered service engineer.

If you have any questions or would like some advice about an existing or new radiator, the team at Great Rads are always here. Simply drop us a message and we'll get back as soon as possible.


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