I am looking at putting a webasto on my tractor that is used on the bag extractor. The timer can only be set to run to 2 hrs at a time, doesnt work very good when you get to a terminal and there is a lineup, get back to bag hour later then suppost to. See you can also use a switch to turn them on, are they able to run for 12 hrs at a time. Would be nice if timer could be set to run for 4 hrs at a time thnks.