Set DIM value after delay?

I am looking for something like a timer, but rather than switch something ON or OFF I want to set a DIM value instead.

My ventilation fan-speeds are now controlled by 0-10V signals. VMB4DC works great for this.
However this means I want the bathroom over-run timer, rather than switching the fan OFF, to just lower the speed to trickle ventilation (our house needs more ventilation generally in winter anyway so bathroom fans help move the air and they scavenge radon too).

Would also be useful as a delayed OFF for lights that are already on.
e.g. to give me time to exit rather than having a button elsewhere to turn them off.
I exit my office, walk down a corridor, then up a staircase. I could put a “switch staircase, corridor, and office lights off” button at the to of the staircase but that is some way from the office so context is lost. An “I am leaving” button in the office sort of makes more sense.

Relay timers only seem to do ON/OFF.
Dimmer timers all DIM between ON or OFF. Cannot dim to a value.

Any good solutions that I am missing?


Hello @EvAndy ,

This may help you further.
With a VMB4DC you can assign the control button ch to a dimming channel of VMB4DC,
then choose a dimming atmosphere as an action => Action 0214.

Best Regards,
Velbus Team

Thanks, that would be great… but how to do this after delay from a timer?

When lights are switched on, set ventilation VMB4DC DIM to 40%.
When lights are switched off start timer for 30 minutes.
When timer expires, set ventilation VMB4DC DIM to 10%

So that if someone takes a shower, the bathroom humidity is quickly reduced.
But afterwards trickle ventilation continues.

For simple ON/OFF of bathroom extract with relay timers, I was using 504.

But now I wish to add control of whole-house trickle ventilation so rather than OFF, I just want to reduce the ventilation to minimum.

I have six spare channels on this VMB8PBU (because only two button used) but the 8PBU does not do any delay-timers, just programs at fixed times.
And the VMB4DC timers all DIM to fully OFF.

there is probably a good way to do it … with 2 relays and such… but the SIGNUM or any other computer (OpenHab/HomeAssistant) makes this waaaaay easier…