I purchased a KW-11 kerosene heater to supplement my home furnace as winter approached. I have had several radiant heaters in the past, which eventually developed a burned-out wick after one to two seasons. This heater worked perfectly for a few weeks, then gradually produced less and less heat. The wick is soft and without carbon hard spots, but simply won't rise high enough to generate meaningful flame and heat. Possibly the gear for raising the wick has malfunctioned. I ended up buying a second heater locally - which works well- and setting aside the KW-11F until I have time to take it apart and fix it (if possible). For the brief time it worked, it produced good heat. Too bad it's not robust enough to last more than two weeks before malfunctioning.