Why Is My Boiler Losing Pressure?

If you are experiencing your boiler losing pressure, it’s important to identify the cause sooner rather than later. Adequate pressure is essential for the system to function efficiently, providing heating and hot water on demand.

Regularly checking and maintaining the correct pressure is important for the overall performance. So, why does boiler pressure drop?

In this blog, we answer that very question – alongside giving plenty of sound advice around checking your pressure, preventing pressure drops and locating potential leaks.

What is boiler pressure?

Your pressure gauge – often located front and centre on your boiler – allows you to view operating levels.

Heating pressure, often referred to as boiler pressure, is the pressure of the water within a heating system or boiler. It’s measured in units like bar or psi.

Maintaining the correct heating pressure is crucial for the proper functioning of the system. Too low pressure may result in inadequate heating or hot water, while too high pressure can lead to system damage or leaks.

Checking and adjusting the heating pressure is a routine part of boiler maintenance.

Typical causes of pressure loss?

A drop in heating pressure in a boiler system can be caused by several factors, including:

1. Leaks: Water leaks in the system, whether in pipes, radiators, or other components, can lead to a gradual loss of pressure.
2. Bleeding Radiators: Releasing air from radiators during bleeding can cause a drop in pressure. Ensure you follow proper procedures when bleeding radiators to minimize pressure loss.
3. Faulty Pressure Relief Valve: A malfunctioning pressure relief valve may release water from the system, causing a decrease in pressure.
4. Automatic Air Vent Issues: Problems with automatic air vents can lead to air accumulating in the system, affecting pressure.
5. System Draining: If the system has been drained for maintenance or repairs and not refilled properly, it can result in reduced pressure.

How do I check if my boiler pressure is low?

When checking the pressure on your boiler, know that a general range of 1 and 2 is ideal and could be described as the correct pressure.

While there is room for a little on either side of these levels, it shouldn’t drop below 0.5. If the gauge on your boiler reads below this, your boiler pressure is too low.

However, we always recommend following the indicators located on your specific boiler or in your boiler’s manual.

To check if your boiler pressure is low, follow these steps:

1. Look at the Pressure Gauge: Most boilers have a pressure gauge on the front. It usually looks like a round dial with numbers and a pointer. Check the current pressure reading.
2. Normal Pressure Range: The typical pressure range for a domestic boiler is around 1 to 1.5 bar. If the pressure is below this range, your boiler may be low on pressure.
3. Check for Error Codes: Some boilers display error codes when there’s a pressure issue. Refer to your boiler’s manual to interpret any error codes on the display.
4. Inspect for Leaks: Visually inspect around the boiler, radiators, and pipes for any signs of water leaks above ground. Leaks can contribute to pressure loss.
5. Bleed Radiators: If you’ve recently bled your radiators or if some radiators feel cold at the top, you might have lost pressure. Releasing air from radiators can lower the system pressure.

If you find that your boiler pressure is low consult your boiler’s manual for specific instructions on how to repressurise it.

How to repressurise your boiler?

If you find your boiler losing pressure: switch off, allow it to cool, and find your filling loop.

1. Turn to open the filling loop handles, at which point you should hear water flowing.
2. Watch the pressure gauge and allow it to increase to the recommended level stated on the gauge and/or your manual (usually around 1.5).
3. Close the filling loop handles completely and turn your boiler back on.

If pressure isn’t maintained after these steps and keeps dropping, it’s time to call the professionals. You may find that you have a leak or you need boiler repairs.

Boiler Losing Pressure: Frequently Asked Questions

Is it dangerous when my boiler pressure drops?

No, low pressure isn’t immediately dangerous. However, you may find that you’re only able to access cold water.

Can bleeding radiators cause pressure loss?

Yes, bleeding radiators releases air from the system, which can lead to a drop in boiler pressure. It’s important to follow proper procedures when bleeding radiators.

Should I worry if my boiler pressure is too high?

Yes, high boiler pressure can lead to system damage. If the pressure exceeds the recommended range, you may need to bleed radiators or consult a professional to address the issue.

How often should a boiler lose pressure?

While there’s no right or wrong answer here, if your boiler is losing pressure daily or weekly, there may be a deeper issue to resolve.

How often should boiler pressure be topped up?

It’s common to need to re-pressurise your boiler up to once or twice a year. See your pressure gauge for guidance.

If you suspect a hidden leak on your heating system Rainbow Restoration can help

If you find your boiler losing pressure and suspect a leak, our Trace & Access and Water Leak Detection services can pinpoint the exact source and repair the issue before it escalates. Our Experienced Leak Detection Technicians alongside our Specialist equipment can help identify the location of a heating leak using non-destructive methods such as Thermal imaging, Acoustic testing, Tracer gas and Moisture mapping.

Once located, we can even get to work on accessing the leak so it can be repaired with the minimum of damage – getting your heating back up and running in no time. This can then be followed up with drying of the affected areas.