How to create a timer on delay


I’m trying to make a timer on delay but i don’t know how to achieve my requirements.
For example i have a temperature sensor that is acting on the water pump of the zone and on the fan coil unit, what i want to create is a delayed start of the fan coil unit in order to give time to the pump for circulate the hot water and avoid cold air coming from the fan. I’ve installed a VMB4RLY for the purpose but seems that the internal function of TON cannot make “delayed on at press and off at release”.

can you help me on this topic?



1 Like


if i’m correct you want to automaticly switch on the fan after a certain time and switch off when the waterpump switchs off. the problem is that you must use the momentary function of the relay. so you can not use the timed on delay. the only solutions to your problem is that you use a ordinary commercial timed delay on relay.
i 've to check for some compagnies that makes such relays.

hope this helps you for now.



At RS-components there is a delay on relay from Schnieder Electric type RE11 RA MU. Can swicth loads at 8A 230 volts mains.



What do you think of this:

You program the relay of the Fan as delayed on
then you program a relay channel X as 1 sec ON after release of the pump (VMB1TS)
now you program the fan to OFF with initiator relay X.

Kris D.