If your boiler keeps losing pressure, you may notice lukewarm radiators, heating that shuts off unexpectedly, or the boiler asking to be topped up more often than it should. This is a very common issue in UK homes, especially in older heating systems across Weston-super-Mare, Worle, Clevedon, and Portishead.
Thankfully, pressure loss doesn’t always mean the boiler is faulty — but it does mean something needs attention.
This guide explains:
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What boiler pressure is
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Why pressure drops
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How to check pressure safely
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When you can fix it yourself
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When it’s time to call a professional
What Is Boiler Pressure?
Boiler pressure is the force of water circulating through your heating system.
Most boilers operate correctly between:
1.0 – 1.5 bar (when cold)
Up to 2.0 bar (when heating is on)
You can check the pressure using the gauge on the front of your boiler.
If the needle is below 1.0, pressure is too low — the system may not heat properly.
Common Causes of Low Boiler Pressure
1. Bleeding Radiators
If you recently bled a radiator, air has escaped and pressure needs topping up.
This is normal and easily corrected.
2. A Small System Leak
Most pressure loss comes from tiny leaks in:
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Copper pipe joints
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Radiator valves
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Underfloor pipework
These leaks may be invisible, but the pressure drop is the clue.
3. Faulty Pressure Relief Valve (PRV)
If the PRV is stuck or damaged, pressure escapes when it shouldn’t.
4. Failed Expansion Vessel
The expansion vessel absorbs pressure changes.
If the internal membrane fails, pressure becomes unstable.
How to Re-Pressurise the System (Safely)
Most boilers have a filling loop.
You top up by opening two small valves until pressure reaches ~1.5 bar.
However:
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Do not overfill the system
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Do not keep topping up every day
If you must refill frequently, there is definitely a leak.
Signs It’s Time to Call a Professional
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Pressure drops daily or overnight
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You can’t locate the leak
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The PRV is dripping outside
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Radiators are cold at the top
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Boiler shuts down due to low pressure
These indicate a system leak or boiler component failure that needs repair.
Professional Boiler Pressure & Leak Repair
We diagnose and repair:
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Hidden heating leaks
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Pressure relief valve failures
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Expansion vessel issues
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Pump and seal problems
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Combination boiler pressure faults
We also balance and refill the system so heating runs efficiently again.
Areas We Cover
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Weston-super-Mare
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Worle
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Clevedon
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Portishead
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Congresbury, Banwell, Yatton & surrounding North Somerset areas
Need Help Fixing Boiler Pressure Problems?
📞 Phone: 07453 304504
📧 Email: matt@teddytailsplumbing.co.uk
📍 Local to: Weston-super-Mare, Worle, Clevedon, Portishead & all North Somerset
Experienced, reliable boiler diagnostics and repairs.
A quick pressure fix today prevents bigger heating issues tomorrow.