|Hot water generation active||– Permanently on: In draw-off mode before burner is on
– Flashing: Burner on in draw-off mode
In System boilers and open Vent boilers – (Please note this function only works on these boilers if the Vaillant junction box and associated VR Controls are being used, otherwise please refer to “heating mode active” article Article). Permanently on means there is a hot water demand being requested by the hot water zone controls / programmer. This usually kicks in a few seconds after the programmer is switched on. When flashing it means the burner is now on and sending heat from boiler down the pipes to the hot water cylinder.
In Combi Boilers / Storage Combis – Permanently on usually means there is a hot water demand being requested due to a tap being open. Flashing means the burner is actually on and heating the hot water.
Possible problems: If this symbol is on or flashing when there is no tap actually open, it would just either there is a leak within the hot water pipework causing the boiler/burner to activate due to there being enough flow of leaking water or if you have a secondary hot water circulator it is possible that the pump is currently running, although not so common on Combi Boilers.