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What You Need To Know About Boiler Pressure

by Rahul

Many modern boilers require little attention, including regular annual service and sometimes a look at the pressure gauge. This gauge indicates the pressure of water circulating in the system. A boiler pressure that is too high or too low can cause problems in the system and render it useless.

Not only will it be inefficient, but it will also increase your Utility Bidder bills. So it is imperative that a correct boiler pressure is maintained at all times to ensure it works efficiently in heating your house… Continue reading if you want to know how to check and maintain boiler pressure.

How to check boiler pressure?

In many modern boilers, the pressure gauge is located on the front or under the control panel. In older boiler models, the pressure gauge will be underneath the pipework. Find your instruction manual if you are unsure of the location. So what should the pressure be on the gauge?

The normal pressure on the gauge should be between 1 to 2 bars. To help you out, the ideal boiler pressure range will be marked as green on the gauge, and too high and too low boiler pressures will be marked red. Even when the boiler pressure is in these red zones, your boiler may continue to operate.

But if it is shutting off or not coming back on, then you have a boiler problem. So to avoid problems, you should occasionally check the pressure even when the boiler is operating properly. In addition to this, you should know how to correct pressure when boiler pressure is too high or too low.

Low boiler pressure

Low boiler pressure is not dangerous, but it can be uncomfortable. It is indicated by

  •         No hot water
  •         Low pressure on the gauge
  •         Radiators not warming properly

The most common causes of boiler pressure continuously dropping include:

  •         You have just bled your radiators 
  •         Or the development of small unnoticeable leaks

You can easily re-pressurize your boiler yourself by doing the following:

  •         Turn off the boiler and look for the external filling loop that can be found under the boiler. This is a short-length hose connecting two pipes that have levers at both sides.
  •         Turn both levers so that they are aligned in the direction of the hose. When doing so, the water will flow, and the pressure will increase.
  •         Shut the valves once the pressure reaches 1.2 bar.
  •         Turn on the boiler when pressure remains constant.

Normally there is no need to re-pressurizing the boiler very often, but if it happens more than once, then check for signs of leaks. If you find leaks, then it’s time for repair work.

High boiler pressure

Normally, a too high boiler pressure is not dangerous because the heating system is protected by a pressure relief valve (PRV), which safeguards against damage by allowing water to escape in case of high pressure. High pressure is indicated by 

  •         Shutting down of system
  •         Pressure in the red zone

There are a number of reasons for pressure rising 3 bars or more, including:

  •         The filling valve may have been left open or not screwed tightly shut.
  •         Or too much water may have been put in when correcting low boiler pressure.

You can lower the boiler pressure yourself by doing the following:

  •         Turn off the boiler and check that the filling loop valve is completely closed.
  •         Once the system cools down, bleed the radiators.
  •         When the radiators have bled, check the gauge. If it is still high, then repeat the process of bleeding until the pressure is in the green zone.
  •         If the pressure becomes too low, then follow the tips above to get it back up again.

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