A boiler most commonly loses pressure due to a leak within the system or when air/water is released from a radiator during bleeding.
Here's a breakdown of the common causes:
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Leaks in the System: This is the most frequent culprit. Leaks can occur at various points:
- Radiator Valves: These are notorious for developing leaks, especially around the valve stem or connections to the radiator.
- Pipes and Fittings: Corrosion, wear and tear, or poorly fitted joints can lead to leaks in the pipework.
- The Boiler Itself: Internal components of the boiler can fail, resulting in leaks within the unit.
- Expansion Vessel: A faulty expansion vessel can lead to pressure fluctuations and eventually leaks as the system struggles to manage water volume changes due to heating.
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Bleeding Radiators: When you bleed a radiator to release trapped air, you're also releasing water. This reduces the overall water volume in the system, causing a pressure drop.
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Automatic Air Vents (AAVs): These vents are designed to automatically release trapped air. If an AAV malfunctions, it may continuously release air and water, leading to a pressure drop.
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Faulty Pressure Relief Valve (PRV): The PRV is a safety device designed to release pressure if it exceeds a safe level. If the PRV is faulty, it might release water unnecessarily, causing a pressure drop.
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Recent Work on the System: Any recent plumbing work, such as replacing a radiator or repairing a pipe, may introduce air into the system or create a small leak.
What to do if your boiler is losing pressure:
- Check for Visible Leaks: Carefully inspect all radiators, pipes, and the boiler itself for any signs of water leakage. Look for drips, damp patches, or signs of corrosion.
- Re-pressurize the System: If you've identified and fixed a small leak or bled your radiators, you may need to re-pressurize the boiler according to the manufacturer's instructions.
- Call a Qualified Heating Engineer: If you cannot find the source of the leak or if the pressure continues to drop after re-pressurizing, it's crucial to contact a qualified heating engineer. They can diagnose the problem accurately and perform necessary repairs safely.
