Boiler Pressure Keeps Dropping — Even After Bleeding Radiators

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Boiler Pressure Keeps Dropping — Even After Bleeding Radiators

If you’ve bled your radiators but your boiler pressure still keeps dropping, it means the issue hasn’t been resolved.

Bleeding removes air — it does not stop water loss.

This is exactly the type of issue our Central Heating Leak Detection service is designed to diagnose properly.

What This Usually Means

If pressure continues to drop after bleeding, it usually means water is still leaving the system somewhere.

The problem isn’t air — it’s loss.

A stable heating system should not require repeated bleeding and topping up to function properly.

Why This Happens

Air builds up because pressure drops. When water leaves the system, air is drawn in to replace it.

What typically happens is:

Water escapes slowly from the system

Pressure drops as a result

Air enters and collects in radiators

The system improves temporarily after bleeding, then declines again

To understand the wider pattern, see our signs of a central heating leak page.

The symptom returns because the cause remains.

How to Tell If This Is the Problem

  • Pressure drops after bleeding
  • The system needs regular topping up
  • Radiators repeatedly fill with air
  • The issue becomes more frequent over time

What Most People Get Wrong

Many people believe bleeding has “fixed” the system because performance improves immediately afterwards.

In reality, it only resets the symptom temporarily.

How the Problem Is Actually Solved

The system needs to be assessed to identify where water is being lost and why the pressure cannot stabilise.

The aim is to stop the loss, not manage the symptoms.

What to Do Next

If pressure keeps dropping after bleeding, it’s important to investigate early rather than continuing to manage the symptoms.

Identifying the cause early helps prevent further instability and avoids ongoing disruption within the system.

Explore more expert advice in our Helpful Guides.

Need help with a leak? We’ll find it and fix it.

If you’re dealing with a similar issue, The Leak Hunter will diagnose the problem, explain the cause clearly, and recommend the most cost-effective next step.

We deal with water, central heating, underground and gas leaks using accurate, non-invasive methods.

Call 01372 613053

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