What normal boiler pressure should do
Most sealed heating systems sit around 1 to 1.5 bar when cold. Pressure rises slightly when heating is on. If the pressure falls again after topping up, the system is losing water or the boiler has a fault that needs diagnosis.
Common causes of pressure loss
- Small radiator valve leaks.
- A leaking pressure relief valve or discharge pipe.
- Expansion vessel faults inside the boiler.
- Air in the system after recent work.
- Hidden pipe leaks under floors or behind boxing.
When pressure loss points to leak detection
If the boiler has been checked and no obvious fault is found, a hidden central heating leak becomes more likely. These leaks can be slow and may not show as visible water straight away.
Repeatedly adding water can hide the symptom while corrosion and damage continue inside the heating system.
What to tell the engineer
Note how often pressure drops, whether it happens with heating on or off, and whether any radiators, floors or ceilings show damp marks. That information helps decide whether the job is mainly boiler repair or leak detection.
Boiler pressure keeps dropping?
Get a practical check from a Gas Safe registered engineer.
Call 07755 744 889