Low Information
73:0 on Viessmann Vitodens 300-W

Your boiler's hot water pump is scheduled to be running, but it may not be operating correctly or is being flagged for an advisory check.

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

DHW circulation pump: ON according to time program

What causes this fault?

This is a status message rather than a mechanical failure, occurring when the boiler's internal clock triggers the secondary hot water pump to run. It indicates that the system is successfully moving hot water around your pipes so it is instantly available at your taps. You may see this code during your scheduled 'on' periods or if the pump has been manually boosted.

DIY fix possible

Check your hot water time program settings on the control panelEnsure the pump is not physically stuck or blockedReset the boiler to see if the advisory code clears

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