Why Is My Boiler Losing Pressure?

If the pressure gauge on your boiler keeps dropping, it is worth knowing what is behind it.

Most boilers sit between 1 and 1.5 bar when the heating is off. If it drops below 1 bar, your boiler may stop working properly or switch itself off.

Why Is My Boiler Losing Pressure?

There are a few common reasons and it is worth knowing which one applies to your situation.

A small leak somewhere in the system

This is the most common cause of a boiler that keeps losing pressure. It does not have to be an obvious drip - even a tiny leak on a radiator valve, a pipe joint or the boiler itself can cause pressure to drop over time. If you have recently noticed water anywhere near your boiler or radiators, read our guide on boiler leaks.

A recently bled radiator

If you have bled your radiators recently, some air and water will have been released which can cause the pressure to drop. Topping it up afterwards is normal.

The expansion vessel needs attention

Inside your boiler there is a component called the expansion vessel which helps manage pressure changes as the system heats up and cools down. If this develops a fault, it can cause ongoing pressure loss. This one needs an engineer.

The pressure relief valve

If this valve has been releasing pressure - which can happen if the system pressure has been too high - it can cause ongoing drops. Again, this needs a professional to look at.

Is Low Boiler Pressure Dangerous?

Low boiler pressure on its own is not dangerous, but it will affect how well your heating and hot water works. Most modern boilers will switch themselves off if the pressure drops too low as a safety measure.

Boiler Keeps Losing Pressure? We Can Help.

KAS Energy are Gas Safe registered engineers based right here in Derbyshire. We are part of the community, which means we can get to you quickly when you need us.

With over 20 years of hands-on experience and 315+ five star reviews from homeowners across Derbyshire and Nottinghamshire, you are in safe hands.

Call 01773 424563 or use the contact form below. Our boiler repairs team cover Derbyshire and Nottinghamshire, and if your boiler is getting on and a new boiler might make more sense, book a free home survey.