chefslot:
could [hysterisis] not be introduced as a delay (5000)?
Hysteresis isn't a time delay, it's using two different temperatures for on and off. So if the thing your're switching is a fan, you might switch it on at 25 degrees as it warms up and needs cooling. But if the off temperature is also 25, it will switch off immediately. So you only switch it off at say 23 on the way down.
So say it starts at 22. All good, but it's warming up. Passes 23, 24. Gets to 25, fan on. Might get to 26 before fan does any good. Starts cooling, 25, fan stays on, passes 24, still on. Gets to 23, fan off. Rinse and repeat.