Rlah -
It doesn't matter if it's 2.25 CF or 3.5 CF, it's the size of the fire you build that matters. A 1.5 cubic foot of wood fire can burn as hot and as efficiently as a 3.0 cubic-foot-of-wood fire. A big stove doesn't change that - all it does is allow YOU to determine HOW BIG you want your fire. 3.0 cubic foot of wood puts off alot more BTUs than 1.5 cubic foot of wood, at a given time (while similarly increasing consumption).
I have a 2.2 cubic foot extremely efficient and well built Lopi wood insert in my 2200 square foot house (that is well sealed, but the layout is poor for heat distribution). I will tell you, bar none, I wish I had gotten a bigger stove. I have NO OPTION to generate more heat, at my size, and I'm not including my basement in these figures. I would need to push this stove to the max to constantly heat 1500 square feet constantly. In other words - another cubic foot of stove size would allow me to have options.
Alot of people push medium sized stoves (2-2.5 cubic feet) because they are great for people wanting supplementary heat. They also consume less overall wood, tend to burn a bit cleaner overall, are more price concious overall, and are probably easier to sell. There is nothing wrong with these stoves.
But you've told us you want to seriously cut down on your heating bills. And you've told us the stove is going to be in an uninsulated block basement (I think) and then going upstairs to ~1200 square feet of living space. And this needs to help you save a bunch through retirement. And you've got a good amount of space for the stove (you aren't space limited) and you've got plenty of wood.
In this recipe, what you want is a ~3.0 cubic foot stove. It will make it possible to literally turn off your furnace/boiler, should you want. You can heat your entire house with it. You will get your 50%+ reduction in heating bills (presuming good and regular usage). It's not much more money. It'll look great. Etc.
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Next, you want a liner. Your chimney is an exterior chimney, which means it gets cold soaked. A 6" stainless steel liner that is insulated will having the following very beneficial properties:
1. It will warm up faster and stay hot easier. This makes chimney gases rise faster, meaning less stick to the walls and form creosote.
2. Further, it creates a far better drafting environment. Draft is the suction effect of the house - i.e. is air being sucked out of your house from your chimney or being pushed down into the house. You want a draft that sucks air from your stove up out your chimney. Such a draft means that when you light a fire, it doesn't smolder and the smoke doesn't pour into the room, but instead the smoke gets sucked up the chimney and your fire gets air moving through it faster - and therefore starts easier. A poor draft is one of the absolute #1 complaints of people on this forum and one of the reasons people decrease their wood burning - because a poor draft is freaking frustrating. You want a nice liner, insulated to maintain draft. They are also rated to absorb a few chimney fires without risking your house. We're talking a $400 investment if you install it yourself.
- Installing a liner yourself in your chimney does not look hard. You go up top and shove a 6" round pipe down a 7" square hole until it hits bottom. You attach it to your stove pipe using easy-to-use joins. You attach is to the top chimney cap using easy-to-use joins. You secure your chimney cap to the top of your chimney. You light a small fire and see if smoke comes out anywhere except the top of the chimney. Done.
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I am not a stove expert, or a chimney expert, or an installer. But I have followed the advice on this forum to great extent, and had nothing but positive experiences every single time I did. These are people who do stuff like visit stove manufacturers, weigh their wood to measure how much it's drying and how long it took, build different stacks of wood to see which one seasons fastest, and post on hearth.com 24/7. These are wood stove NUTS.
They are not trying to sell you something except a positive wood burning experience. Look for the ones who have been here longest and have the most posts to be the ones whose words are sacred writ
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On a last note, your existing stove will serve a purpose and will pump out heat. The heat you get into your house in a function of 3 things:
1. The size of the fire you build
2. The amount of steel/metal the fire heats that than then radiates/convects into your home
3. The efficiency of the stove in terms of air it's sucking in from your home (conditioned/heated air) and then putting it up the chimney, as well as how many BTUs it extracts from a given pound of wood.
Your existing stove will function just as well in #1 and #2 as any modern stove, for the most part. #3 is the big difference.
A modern stove sucks less room air into the fire and converts more of the wood into heat than an old stove. In real terms, this means you keep more of your heat in your house and each load of wood you put in generates more BTUs (because it's combusting twice, as wood, and the smoke re-ignites in the secondary burn tubes).
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The choice is obviously yours. You can save ~$1,200 by simply refurbishing your existing stove and re-using it. It won't heat nearly as well, will use more wood, won't draft as well, and will probably require more cleaning when you start burning alot of wood. And, in my opinion, you are more likely to tire of it and use it less.
Or you can outlay money at a time when money is tight. It'll heat better, draft better, use less wood, require less cleaning, and for a 3.0 cubic foot stove you can get 8-10 hour burn times out of a single load of seasoned hardwood. You'll almost certainly enjoy it more, but you'll pay upfront for it.
We're here to support you either way. Plenty of old stove burners on here, and plenty of guys who share their new stoves too.