I replaced an 30 year old wood furnace with the Tundra. It is a well designed and built device and is doing an excellent job of warming my home. And, like other wood fired stoves I have used over the past 40 years, it keeps itself warm 5 hours after being stuffed full of good wood if not refilled at that time. Kudos to you folks for building what should have been done 35 years ago and works just like the older, standard furnaces. Regards, Bob Robblee