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HVAC

How to Fix a Boiler Losing Pressure

Quick Answer

Check the pressure gauge, repressurise using the filling loop, and check for leaks.

How to troubleshoot a Boiler Losing Pressure

A boiler losing pressure is a common issue that can affect your heating. This guide covers diagnosing and fixing the problem.

Step-by-Step Fix

  1. Locate the pressure gauge on the boiler front panel.
  2. The pressure should be between 1 and 1.5 bar when cold.
  3. If below 1 bar, locate the filling loop (silver flexible hose).
  4. Open both valves slowly and watch the pressure rise to 1.5 bar.
  5. Close both valves firmly and check for any leaks.
  6. If pressure drops again quickly, there may be a leak in the system.

Common Error Codes

CodeMeaningResolution
E119Low system pressureRepressurise using the filling loop.
Pressure drops quicklyLeak in the systemCheck radiators and pipes for visible leaks.

Frequently Asked Questions

Why does my boiler keep losing pressure?

A leak in the system or a faulty expansion vessel.

Can I repressurise my boiler myself?

Yes, using the filling loop, but check for leaks afterwards.