Low Information
D.18 on Vaillant ecoTEC plus Regular

Your boiler is currently set to run the pump continuously, which is usually a temporary setting used during maintenance or to prevent freezing.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description

Pump's operating mode (Eco: intermittently operating pump, Comfort: continuously operating pump)

What causes this fault?

This code appears when the boiler’s internal settings have been adjusted to keep the pump running all the time, rather than only when heat is needed. It is typically triggered manually by an engineer during a service or by a specific external control system that is requesting constant circulation. In some cases, a communication error between an external thermostat and the main control board can cause this setting to stay active unexpectedly.

This status is sometimes seen during extreme cold snaps if a frost protection mode has been activated to prevent the pipes from freezing.

DIY fix possible

Check your thermostat settings to see if 'Comfort' or 'Always On' mode is selectedNavigate the digital display menu to adjust the pump operating modeReview the user manual to change the pump setting from 'Comfort' back to 'Eco'

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