Hi Justin, here in Western Montana, we are not quite as cold as your location.
But like you, our fires start in September and easily go into May. March is fully capable of at-or-below-zero temps.
As a long-time lurker interested in RMHs, I assume you have seen my shorty core build.
Our house is small, apx 600 squ ft. An original 96-year-old 300 squ ft log cabin with 5 additions. Long with lower doorways that make it hard for heat to travel.
For 40 years, we heated with a homemade stove, A two foot piece of 20" Alaska pipeline, 3/4" thick, with a homemade door. I estimated we burned apx three cords a season. It was always hot in the cabin, getting colder as you headed through the kitchen addition to the bathroom and the laundry room additions.
We have an original wood cook stove in the kitchen that we used to keep that end of the house warm during extreme temps. In later years, we installed a small, non-vented propane heater in the bathroom addition to make sure no pipes froze overnight.
Then I built Shorty. OMG, having 500 clay bricks and an insulated firebrick core in your home is mind-blowing!
When you enter our home now, as soon as you step into the kitchen, the warmth envelops you completely. As you move through the house, the temperature doesn't change; it's just as pleasant in the back bedroom as it is in the farthest addition laundry room, or three feet away from Shorty. We now have windows cracked open all winter, at times even overnight!
The only issue we have found for us is that during early shoulder season, it is almost impossible to use Shorty without overheating everyone.
Our answer is the kitchen cook stove. For chilly mornings or rainy days, a quick fire in it is perfect to take off the chill without overheating the house.
Last year, as an experiment, I separated one cord of doug fir and larch, to be used exclusively in Shorty.
We like our house warm, so by spring I had used one full cord and perhaps another 1/4 cord.
So, although the 3-cord figure is a guess, Last season I only used 1.25 cords in the house, well over a 50% reduction.
How well it will work in a two-story house, I cannot say for sure, but going by my results, I expect you would take longer to heat your space; perhaps instead of one or two fires a day, you might need three or even four when the arctic blasts settle in.
After living my whole life with wood stoves that get lit in October and never are allowed to go completely out until April, having a masonry stove is beyond belief.
No fires all night, no fire most of the day... You can leave for all day, and the house is just as warm when you return as when you left.
You never need to worry about a chimney fire when you are sleeping, or not home, because there is no fire!
And then to put icing on the cake, there is NO creosote ever, only super fine fly ash in the firebox.
The bell/ stratifacation chamber takes years to build up enough ash to need to be cleaned out.
13 acres in extreme rural Montana 100% off grid since 1983. Solar and micro hydro. Summer time piggy farmer. Restoring 2000-04 Subaru outbacks wagons for fun and a little profit. Not quite old enough to retire YET but closing on it fast... until then I must occasionally leave Paradise "home" and run large construction cranes on union job sites across the inland northwest. I make (Well try) A-2 A-2 cheese, I love cooking with my wood smoker for everything! Would not live anywhere else but rural Montana ! My wife Liz runs "Rocks by liz" a successful Etsy store and we have a summer booth at the Missoula peoples market. We currently breed and raise persian cats but are about to retire all the girls and let them be happy kittys for the remainder of their days.Oh and my biggest thing is... I LOVE MY RMH !
