Baxi Chronic Pressure Loss

Furnace frequently loses pressure and needs topping up often

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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

Leaking system pipework or radiators, Faulty pressure relief valve (PRV) passing water, Failed expansion vessel, Micro-leaks inside the boiler

How to Fix / Troubleshooting

Safety: Allow the system to cool before inspecting the PRV discharge.

  • Check PRV outlet: Locate the pressure relief valve discharge pipe outside. If it drips regularly, the PRV may be passing.
  • Inspect for visible leaks: Check all radiators, valves, and accessible pipes for signs of water staining or damp.
  • Expansion vessel test: A professional can check and recharge the Baxi expansion vessel pre-charge pressure. A flat vessel causes frequent pressure spikes and PRV discharge.
  • Replace faulty components: PRV and expansion vessel replacement should be done by a heating engineer.
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Repair Difficulty

Hard 4/5

Required Part

Expansion Vessel and Pressure Relief Valve
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