Boiler Losing Pressure? Common Causes and What to Do

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A boiler losing pressure is a common winter problem. Your radiators go cold, or the boiler shuts down. Often the cause is simple, but sometimes it needs an engineer.

What is boiler pressure?

Your central heating is a sealed system full of water. The pressure gauge shows how much water is in it. Most boilers work best at around 1 to 1.5 bar when cold, although your manual gives the exact figure.

Why is my boiler losing pressure?

There are a few usual causes.

  • A leak in a pipe, radiator or valve
  • A bleed radiator that let some water out
  • A faulty pressure relief valve
  • A problem with the expansion vessel
  • A worn seal inside the boiler

Homeowner checking a boiler losing pressure

What you can safely check

First, look for damp patches or drips around radiators and pipes. Next, check the pressure gauge. If it is low, your manual shows how to top it up using the filling loop.

However, do not keep topping up again and again. If the pressure drops every few days, there is a fault. Water is escaping somewhere.

When to call an engineer

Call a Gas Safe engineer if the pressure keeps falling. Also call one if you see leaks near the boiler, or hear banging or gurgling. Never open the boiler casing yourself.

You can check any engineer on the Gas Safe Register. Our article on how to tell if your boiler needs repair lists other warning signs.

Fast help from BCA

BCA repairs boilers across Grimsby, Cleethorpes and the surrounding areas. Contact BCA and we will find out what is wrong. If the boiler is very old, a new boiler quote may be worth a look.

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