Okay, I don't want to be long winded but here it goes. Purchased a used Mount Vernon Non AE model used about a month ago. This unit is horizontally direct vented out of the house. The problem I am having is that sometimes the stove will fire up without any problem when the thermostat calls for heat. Other times, the red call light is on but stove is not running. It appears that it is dropping pellets upon the call for heat but it dies out after catching. What I am wondering is, does this stove need to have the outside air kit installed? Would relying on the inside air of the house instead of having an outside air kit contribute to this problem. If anyone responding has some questions to ask me in order to fix this problem, please don't hesitate to ask. I love this stove but when I have to get up at 2AM because it didn't fire up, it gets dissapointing.