Boiler Pressure Keeps Dropping? What to Know
A boiler that consistently loses pressure is losing water somewhere in the system. This needs professional investigation to identify the source.
Urgency: Medium urgency
Possible Causes
- A leak in the pipework (may be hidden behind walls or under floors)
- Failed expansion vessel
- Faulty pressure relief valve
- System not fully bled of air
- Open or leaking radiator vent
Safe Homeowner Checks
These observations do not require touching the equipment.
- Check the pressure gauge reading (should be 1–2 bar when cold)
- Look for visible water stains or pooling around pipes and radiators
- Check if you need to repressurize the system frequently
- Note whether the pressure drops faster when the heating is running
Next Steps
- A small pressure drop over weeks may be normal; dropping to zero within days indicates a leak
- Do not keep repressurizing without investigating the cause
- Professional pressure testing can locate hidden leaks
Safety Reminder
If you smell gas, suspect carbon monoxide or believe there is an immediate danger, leave the property and contact emergency services or the appropriate gas emergency authority. Do not remain inside — exit the building immediately and call for help from outside.