Boiler Pressure Keeps Dropping
The boiler pressure gauge keeps falling below 1 bar, causing the boiler to lock out or lose heating efficiency.
What Is Causing This?
- 1Small leak in the central heating system
- 2Faulty pressure relief valve
- 3Expansion vessel lost its charge
How Urgent Is This?
This should be fixed in the coming weeks. Leaving it may allow the problem to worsen and cost more to repair.
What Needs to Be Done
A Gas Safe engineer will pressure test the system to find any leaks, check the expansion vessel, and repair or replace faulty valves. They will re-pressurise the system.
How Much Will It Cost?
National average estimate
Labour: £85 – £200 | Materials: £30 – £178
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Prices are estimates based on typical UK rates. Actual costs depend on the specific issue, accessibility, and your location. All quotes from tradespeople on Tradesfolk are completely free.
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Ask a QuestionHow to Prevent This
Check the boiler pressure gauge monthly. Do not keep topping up the pressure without investigating why it drops. Have the expansion vessel checked at each annual service.
Related Problems
Loud banging, kettling, or rumbling sounds coming from the boiler, particularly when the heating or hot water comes on.
The boiler shows an error code, flashes a warning light, or simply will not ignite when heating or hot water is called for.
Water dripping from the connection between the radiator and the valve, often leaving a pool on the floor.
Other Gas Engineer Problems
Loud banging, kettling, or rumbling sounds coming from the boiler, particularly when the heating or hot water comes on.
The boiler pilot light repeatedly extinguishes, meaning the boiler will not fire up for heating or hot water.
A smell of gas (rotten eggs) inside the house, which could indicate a gas leak.
The boiler shows an error code, flashes a warning light, or simply will not ignite when heating or hot water is called for.