Im bring this back up because this week we have finally got a real arctic blast of cold air to test my work I did this summer.It has been cold and windy the last few days here,thursday night was 15-16 degrees with 25-40 mph winds.Temps never got over 25 yesterday for a high.The Shaver is finally having to work a little,and I must say that I am very happy with the improvement in burn times from my increases in insulation,esp with windy weather.It seems me filling in all the voids,and air gaps and adding insulation over,and under has added a few hours to my burn times easily. I just came in from loading the boiler,and when I opened the door,I was suprised to see a lot of wood remaining,the front portion of all the logs were burnt,but the back 1/2 of them were still intact!I grabbed the poker,an pulled them into the hole up front,added one large crotch that i save for daytime burns because they take up a lot of space.I am going out in the Am now on overnight burns with enough still in the firebox to last all day if i wanted too,even in this cold snap.I feel the extra insulation is definitely worth the time and money.You dont need to use spray foam,although im sure it would help even more,$50.00 worth of batts worked great for me.