I'm trying to run two fans when there is a call for heat but I want fan 2 to shut off a few minutes later. I don't have an off delay timer however I do have an on-delay timer and a relay. I know it can work I just can't seem to figure it out.
Figure 1. Timing diagram and circuit schematic.
How it works:
- TIMER1 is normally energised but when power is first switched on at the mains FAN2 will run until the timer times out.
- When SW1 is closed FAN1 will run, RLY1 will be energised and power off TIMER closing its NC contact causing FAN2 to run.
- When SW1 is opened FAN1 will switch off and RLY1 will drop out.
- TIMER will begin timing and when the set time has elapsed the TIMER contact will switch to the NO position switching off FAN2.
This pre-supposes that both the relay and timer have changeover contacts (but you gave no details or datasheet links).