How to Increase Boiler Pressure? A Complete Guide

how to increase boiler pressure

Learning how to increase the water pressure in your gas boiler is a task that can be completed without needing to call out a Gas Safe registered heating engineer.

Boiler issues are unpleasant to deal with. They may result in problems like a cold bath, ineffective home heating, and eventually pricey boiler repairs. Pressure is frequently the root of boiler problems.

The filling loop, which is typically located on the underside of gas boilers, must be found in order to increase the water pressure in your boiler. Two tap handles on the valves at either end of the filling loop (or flat-head screws on older boilers) should be present.

To let cold water into your heating system, you must open both valves; you should hear the water flowing. The valves should be closed when the pressure reaches 1.5 bar while keeping an eye on the pressure gauge. Restart your boiler and (if necessary) reset the fault code after both valves are firmly closed.

The steps below can help you learn how to raise boiler pressure.

How to Increase Boiler Pressure?

Homeowners frequently inquire about how to raise boiler pressure. To make sure that performing the procedure yourself is safe, you should first check your operating manual before moving forward.

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If you are happy to proceed, you can then increase boiler pressure using the following steps:

  1. The entire heating system needs to cool before work can be done on it, so turn off the boiler.
  2. Check the loop used to fill the boiler. There is a silver connection here between the mains and the main central heating circuit. An isolation valve will be located at one end, and a handle valve will be located at the other. Make sure the filling loop is securely attached at both ends because it can leak and result in a loss of boiler pressure.
  3. Once the line on the valve is directly in line with the pipe, counterclockwise turn the isolation valve. The ideal tool for this is typically a flat-head screwdriver.
  4. The handle valve should be turned the other way. As a result, water can move through the system, bringing the pressure levels back into balance.
  5. While doing this, keep an eye on the pressure gauge. As you open the handle valve, the gauge should rise. Stop once it reaches the recommended level for your boiler
  6. Turn the isolation valve clockwise first, then the handle valve, in the opposite order from before to close both of them.
  7. To test whether the boiler is now operating properly, turn it on.
how to increase boiler pressure

How to Increase the Boiler Pressure Without a Filling Loop?

A filling loop is incompatible with some boilers; this is especially true of older combi boiler models. In some cases, a boiler may have a filling key rather than a filling loop. The steps for repressurizing a boiler using a filling key instead of a filling loop are slightly different:

  1. Turn off the boiler.
  2. Unlock it by putting the filling key into the keyhole.
  3. Make sure water is flowing through the valve by the key by turning it. Either a wrench or a spanner is the best tool to use.
  4. Once it reaches the level advised for your boiler model, keep an eye on the valve. This will be described in the boiler manual.
  5. Reopen the valve, then restart the boiler.

What If I over Pressurise My Boiler?

Remain calm if you unintentionally overpressurize the boiler. Bleeding your radiators is the simplest way to restore the proper level of pressure. Although the process is fairly simple, it takes a long time and is best avoided.

What to Do If the Boiler Does Not Repressurise?

If you have followed the above instructions, but the pressure in your boiler drops as soon as you close the valve, there most likely is a sizable leak. Additionally, your pressure release valve might be broken.

For an inspection of your boiler system in this situation, contact a Gas Safe Registered engineer. Repressurizing the system is not something you should attempt to do repeatedly because it might lead to more harm.

What is the Correct Pressure for My Boiler?

how to increase boiler pressure

The majority of gas boilers operate at a pressure between 1 and 1.5 bars. This will appear on the pressure gauge of the majority of boilers as a green zone. When there is little or no demand, this is the pressure they typically sit at; if you are using heating or hot water, the pressure may rise.

A problem with the expansion vessel or pressure release valve could be indicated by an increase of more than 1 bar when the heating is on and at temperature.

Where Can I Find the Pressure Gauge?

The pressure gauge on a gas combi boiler or system boiler will be in the control panel and should be simple to find.

The pressure gauge for heat-only (or “regular”) boilers installed on pressurized systems will be mounted in the pipework directly beneath the boiler. Open-vented central heating systems are not pressurized and do not have a pressure gauge. They can be identified by the feed and expansion tanks in the loft.

Conclusion: Increase Boiler Pressure

Although you don’t need to be registered with Gas Safe to increase your boiler’s pressure, you should never try to repair your boiler on your own. If you are not registered with Gas Safe, it is against the law to work on gas appliances.

You should ask a qualified engineer to take a closer look at your boiler pressure if after taking these actions you are still dissatisfied with it.


What Happens If Boiler Pressure is Too Low?

A system is more likely to develop leaks if the boiler pressure is too high. But if the boiler pressure is too low, the system won’t work as well. Therefore, maintaining the proper boiler pressure is crucial to ensuring that your system heats your home effectively.

Can I Fix Low Boiler Pressure Myself?

To see if there is low pressure, check the pressure gauge on the front of the boiler. Leaks and recently bled radiators are examples of low-pressure’s causes. You can increase the pressure by putting more water into the system via a filling loop. If the issue is still present, call a Gas-Safe engineer.

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