Hope this is considered on topic (I can start a new thread if its viewed as not) but I think it would be of interest to Cocooners if some methods of determining "run time" a filter sees would be described in some detail.
For instance, I don't do this but am considering it after reading posts here and over HS land, and that is to place a small piece of carboard with a magnet between the filter and the door so when the furnace is ON the magnet will get sucked into the filter and trip a sensor. Then have a timer start in my Ocelot. When the furnace is off the magnet again trips closed and stops the timer. When the timer gets to a certain number alert Homeseer to make an announcement and email me that the furnace's filter needs changed.
Anyone do something like this? I think it would make a great How-To. I could incorporate Ocelot methodology. If someone else could incorporate Elk programming details, I would list that as well.
Just looking for some ideas. A DS10a implementation comes to mind as I doubt most people have wires running to their furnace filters (though I DID run a pair to my friends three filter intakes for his new house