Condensing boiler produces little or no condensate despite frequent operation.

Safety first: Ensure safe access to the condensate system.

• Check flow temperature: Lower the boiler flow temperature setpoint to encourage condensing (e.g. 50–60 °C instead of 80 °C), if compatible with the system.
• Verify weather compensation: Enable or correctly set weather-compensated control if available.
• Inspect condensate trap: Ensure the trap is installed and filled with water; a dry trap may allow flue gases to bypass condensation.
• System design review: High return temperatures from poorly balanced or oversized radiators may prevent condensing.

When to call a professional: A heating engineer can optimise system design and control settings for condensing operation.