View Full Version : Programming question - lower and upper limits

06/11/2005, 06:24 AM
I don't want the fan to switch on and off too quick but i also don't want wide temp swings.

Will this be OK:

If Temp > 79.5 Then FAN ON
If Temp < 79.0 Then FAN OFF

06/11/2005, 10:34 AM
looks good to me...

06/11/2005, 03:04 PM
It should be fine.


06/11/2005, 04:56 PM
Here is how I control mine.

If Temp > 79.6 Then FAN ON
If Temp < 79.5 Then FAN OFF
Max Change 010 M Then FAN OFF

You can use the Max change command to eliminate rapid on/off cycling.

06/15/2005, 08:47 AM
mmmm it didn't work. I entered:

If Temp > 79.9 Then FAN ON
If Temp < 79.7 Then FAN OFF
Max Change 010 M Then FAN OFF

But the fan is switching on and then off within a minute and then on withiin a minute and so on...

06/15/2005, 08:58 AM
Double check and make sure max change is 010 M and not 001 M by mistake?

06/15/2005, 08:59 AM
i did copy/paste so it's how it appears above

06/15/2005, 09:47 AM
The Max change statement only effects either the on state or the off state - not both. So the Max Change statement above keeps the fan off for at least 10 minutes before it is allow to turn back on. There is no time constraint for the ON state.