Boiler frequently loses pressure and needs topping up every few days.

Safety: Allow the system to cool before inspecting for leaks.

• Visual inspection: Check all visible pipework, radiator valves, and joints for signs of dried water marks or corrosion.
• Check PRV outlet: Look at the pressure relief valve discharge pipe outside. Any dripping indicates PRV or expansion vessel issues.
• Test expansion vessel: Follow the procedure to check and recharge the expansion vessel on the Klimosz boiler. Replace if the diaphragm has failed.
• Isolate boiler (combi): Close the heating flow and return valves under the boiler and leave overnight. If pressure still drops, the leak is inside the boiler (e.g., plate heat exchanger) and needs professional attention.