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What To Do When Boiler Pressure Drops too Low

What To Do When Boiler Pressure Drops too Low

A very common problem with boilers is the pressure dropping too low.  This can prevent your system from heating up as normal or can stop the system from coming on altogether  So what can cause the pressure to drop too low and what can you do about it?

What causes low pressure?

Your boiler needs to operate at a certain pressure, generally between 1 and 1.5 bar, and this will be displayed on a circular gauge on the front of your boiler.  Sometimes, if the balance of water and air in the system is disturbed, it will drop below the necessary level and cause problems with the central heating. This can occur if there is a water leak somewhere in the system but it can also just happen if the radiators have been bled and air has been released from the system. 

How do I fix it?

The first thing to do is to visually check around your boiler, pipes and radiators to see if you can identify any leaks, drips or damp patches.  If these are found, they may be the result of a loose joint or fitting and you could try re-tightening to stop the leak.  However, if it is a more serious problem you would need the help of a professional.  The leak may be inside the boiler itself and a professional could fix this too.

Once any problems are fixed, or you've determined it's the result of a radiator bleed, then the next step is to repressurise the system.  This is an easy process and will be explained clearly in your boilers instruction manual or you can watch the following video for a simple demonstration.

When do I need to call an expert?

Whilst low pressure is a common and simple issue to fix, if the underlying cause isn't addressed then the problem will keep occurring.  A professional should be contacted if you are unsure of what is causing the pressure to drop, if it is a leak or break you can't fix yourself or if you don't feel confident in adjusting the boiler yourself.

Published: 22 November 2021

Tags: help, boiler, pressure