I do two loads per 24 hrs usually. One 14 hr burn and one 10 hr burn, that's just how our work schedules fall. When overnight lows fall into the single digits with highs in the teens, I'll burn a partial load in the evening. My house is easy to heat.
Have you ever looked at Buck Stoves BB. I am starting to get a handle on mine now and have seen very few bad reviews.
The temp spikes are a huge benefit with a cat stove from my experience. With my non cat I can remember laying on the floor in the stove room to escape the heat after loading up for the night, the stove room is much more comfortable with the cat stove. I used to hate the house always being silly hot, I'm much happier being able to dial down the stove and keep the stove room in the mid 70's and the rest of the lower level anywhere from 69-72. Before I installed the BK I thought the roller coaster ride temp swings were part of heating with wood, after I got the BK running I realized it didn't have to be that way. If you like keeping the house silly hot a BK probably won't benefit you much during the heart of the winter as it will during the shoulder season.
Insulating is on the list of things to do when the house is mine. But unfortunately its held up in a trust dispute. If I get the home I want to update the electrical system and adding insulation before that will make that more difficult. Plans are also to claim the garage for a mud/utility room.
I would definitely insulate the attic first and see what happens. The fact that you use the Mansfield the way I used the Heritage makes me wonder if the Princess and/or Steel would give you the 12 hours you are looking for. I can not say for sure at this point since you probably have a good deal of heat loss like I do/did. Last thing you want to do is spend the money/time/effort bringing in a new stove only to see no greater improvement when temps got real cold. I know I am over-sized for my needs and I still have a nagging feeling in the back of my head questioning the Princess.
Cold weather its full load at 11-12pm, full at 7-8am, and small load around 6 gauging size to heat and have the right amount of coals for the night load. 24 hr not so cold is 2 12hr loads. And then there's shoulder season.
I have. I do not think they will fit my specific needs. Let me explain why: The Bucks I would be interested in an require 8" liners. I would feel okay running a Buck on a 6" liner where the 30 is, but not where the Defiant and the Encore are. Upgrading those two chimneys to 8" liners are not possible due to the size of the chimneys. The Buck cat stoves do not seem to be as efficient as the BK and Woodstock cat stoves. This doesn't make them bad stoves, but they do not provide the long burns I am looking for. The Buck 91 reports that I have seen seem to indicate it will give you a 12 hour burn and are not known for their long and low burns. 12 hours is nothing to sneeze at, but I need 12-15 hours during cold temps and 20+ during mild temps. I have not seen anything that indicates the large Buck cat stoves can provide this. Again, doesn't mean the Buck is a bad stove. But, my expectations are very specific for my next stove upgrades.
If you wanted to be on a roller coaster ride try out my old stove...2-6 hr loads and I could run the living room temp up to 90. I'm not unhappy with the Mansfield it's been a good heater. The only irritating thing about it is the high flue temps.
Yes, the Vigilant was also a bit of a bastard like that. Have you tried the damper yet? If you can hit nearly 700 with the Mansfield, the damper should work for you.
Ya I run a damper. It'll knock 100-200 of the flue temps. But I can't use it until 45-60 minutes in on a load most times or the stove temps will stall. And then I get more smoke at the end of the burn.
I wouldn't advertise these as typical. WS claims 8-10 hr burn time and that is probably what most people would see in an appropriately sized house in a colder environment. And at 14 hrs the STT is down to about 170-200F, enough coals to restart without any kindling. I'm sure anyone can get a 14 hr burn out of a KS with oak, but most need more heat than 2.8 cuft (two loads) per 24 hrs.
I don't think I had fully realized the temp spikes/swings of a tube stove. Not to bash tube stoves, I've never been around one. My big old smoke dragon would cruise along like the Keystone, or cherry the pipe if you wanted it to. Of course it made tons of creosote while cruising at low burn where I needed it.
It's not really a swing. You get them up to temp, somewhere between 600 and 750, and then they slowly come down. On a full, tightly packed load, 2-3 hours in the 600-750 range for the most part. Then 2-4 hours in the 450-600 range. The 2-3 hours in the 300-450 range. Than another hour or two in the 200-300 range. From peak temp down to 250 degrees, on a full load, you can expect 7-12 hours.
I consider the Vigilant to be a swing burn. It would burn too hot so you close the air down a bit and then it crashes. Open the air up and it swings back up to really hot temps. Adjust the air a bit and it crashes again. With the modern non-cat stoves it is a hot peak and a slow walk back down.
Just talking about stoves and how cat stoves, when sized appropriately, can provide usable heat over long periods of time at low settings.