If your boiler pressure keeps dropping, you’re not alone. This is one of the most frequent heating issues homeowners experience in Weston-super-Mare, Worle, Portishead, Clevedon, and across North Somerset.
The good news is that a pressure drop is usually fixable — but it’s important to understand what’s causing it. Repeated pressure loss often indicates a small leak or a system imbalance, rather than a major fault.
Let’s break it down simply.
How to Know Your Boiler Has Low Pressure
Most boilers display pressure on a gauge on the front panel.
Normal boiler pressure (when cold):
1.0 – 1.5 bar
If the needle is:
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Below 1.0 → the pressure is too low
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Above 2.5 → the pressure is too high
Low pressure can cause:
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Intermittent hot water
Common Causes of Boiler Pressure Loss
1. A Leak in the Heating System
Even a tiny, slow leak from:
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A radiator valve
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Pipe joint
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Expansion vessel seal
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Underfloor heating loop
…can gradually reduce pressure.
These leaks are often silent and hidden behind walls or flooring.
2. Air in the System
If radiators have air trapped inside, the boiler must work harder — reducing pressure.
Signs include:
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Gurgling sounds in the pipework
Fix: Bleed radiators and re-pressurise the boiler.
3. Faulty Pressure Relief Valve (PRV)
If the PRV is stuck open or has been activated previously, it can slowly release pressure from the system.
You might notice:
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A small drip from a copper pipe outside the house
This valve usually needs repair or replacement.
4. Failing Expansion Vessel
The expansion vessel absorbs pressure changes as the water heats and cools.
If it loses charge:
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Pressure rises when heating is on
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Pressure drops drastically when heating is off
This is very common in older systems.
We can recharge or replace the expansion vessel if needed.
Can You Re-Pressurise the Boiler Yourself?
Yes — if the cause is minor.
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Turn off heating
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Locate the filling loop (small silver/black braided hose)
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Slowly open valves until pressure reaches 1.3 bar
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Close the valves and restart the boiler
If pressure drops again → the issue needs diagnosing.
Don’t keep topping it up — this hides the problem and can cause more damage.
When to Call a Professional
Call if:
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Pressure drops daily or weekly
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You see water marks, damp or corrosion
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Radiators need frequent bleeding
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Boiler keeps locking out
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Outdoor pipe is dripping
These are signs of an underlying fault.
We trace and repair the problem — not just the symptoms.
Areas We Cover
Boiler repairs, pressure diagnostics & heating system maintenance across:
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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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Nailsea, Congresbury & Yatton
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Banwell, Winscombe & Cheddar
Reliable, tidy and clear communication throughout.
Need Help with Your Boiler Pressure?
We diagnose the cause and fix it properly — no guesswork, no temporary fixes.
📞 Phone: 07453 304504
📧 Email: matt@teddytailsplumbing.co.uk
📍 Serving: Weston-super-Mare, Worle, Clevedon, Portishead & all North Somerset
Clear advice, fair pricing, and repairs that last.