Buderus Chronic Pressure Loss

Boiler frequently loses pressure and needs topping up

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Leak in heating circuit pipework or radiators, Faulty expansion vessel (loss of air charge), Dripping safety relief valve, Micro-leaks inside boiler hydraulic block

How to Fix / Troubleshooting

Safety: Do not overfill the system. Repeated topping up introduces oxygen and accelerates corrosion.

  • 1. Visual leak check: Inspect all accessible radiators, valves, and visible pipework for signs of water or staining.
  • 2. Safety valve discharge: Check the safety valve discharge pipe outside. If it is wet or dripping, the valve may be passing due to high pressure or a failed expansion vessel.
  • 3. Expansion vessel test: With the system depressurized, a technician can measure the air charge at the Schrader valve on the Buderus expansion vessel and recharge or replace it if necessary.
  • 4. Internal leaks: Remove the boiler casing and look for signs of dried deposits or rust indicating slow leaks.
  • 5. Pressure test: If no leaks are visible, a heating engineer can pressure-test the system to locate hidden leaks under floors or in walls.
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Repair Difficulty

Hard 4/5

Required Part

Expansion Vessel / Safety Relief Valve
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