I was checking in, and I came across Glenn's post in this thread:
Glenn Herbert wrote:what reduction in wood use has been reported by people who have replaced an old woodstove with the latest efficient models?
If they have cut wood use in half or less, the fact would presumably be significant enough to mention.
It seemed like it was worth adding a data point to the body of Permies knowledge.
TL; DR - I bought a top-of-the-line woodstove and cut my wood consumption by more than half.
I moved my family into our current house in summer of 2013. This is our fourth winter here. We haven't changed anything about the house. It's a little under 1,000 square feet (92 sq m), poorly insulated, and the woodstove has been the only heat source.
The first winter, we used a Vogelzang Boxwood Stove, and we burned right about four full cords of wood (twelve 16" face cords).
Cleaning up the used stove:
The second winter, we used an antique Acme Jewel woodstove. Same four full cords. (A bit of trivia- our stove was built in the 1890's in Detroit, which was The Stove Capital Of The World for a few decades before it was Motor City.)
Cleaning up THIS used stove:
This is the fourth winter, and we're on pace for the same two cords as last year.
Now, real life is messy, and as you might expect, there were confounding factors. The big one is the fact that, in Michigan, the winters of 2013/2014 and 2014/2015 were unusually cold, and the winter of 2015/2016 was unusually warm. 2016/2017 is on track to be unusually warm, too, and it would be tempting to say, "Well obviously, Mike, THAT's why you're burning less wood." But there's an offset. Last winter and this winter, I've been burning ANOTHER woodstove, a little bitty one out in my office in the yard. It's not an efficient model, and the office isn't an efficient building, so it's eating up plenty of wood.
I figure, very roughly and without any hard data, that the mild weather and the additional building just about cancel each other out. I feel confident in saying the Ideal Steel keeps us warm with half the wood of the Vogelzand or the Acme Jewel. It also does deliver on the load-it-every-twelve hours promise, too. I fire it morning and evening.
I would have liked to have built a masonry stove to say I did it myself, but my wife wanted something that was definitely going to get finished, which is fair.
Without question Vogelzang (just a name brand for US Stove Company) is a cheap, junk stove right off the showroom floor. Now I say this, but had one, and got it to burn very efficiently. The key is making it air tight.
Vogelzang is cheap because they company just flat out does not do that at the factory. I had a cheap $400 pot bellied stove and got it to work just as good as a new high end model by sealing it up. Now this cost money as I had to buy the stove gasket cement, the fiberglass rope, and plenty of pop rivets to get everything to seal, but it worked. While I was at it, I added a bimetal spring temperature control and fabricated a handle for the door so that when it shut, not only did it press against a stove seal, it could be latched for tightness. I am not talking in just a few places I installed a stove gasket, it was sealed everywhere!
This took a fair amount of work, and fabrication knowledge. It was not rocket science by any means, but a person would have to have a little confidence in themselves to take a drill and start boring holes in a stove to put in a bunch of stuff, not to mention fabricating movable flappers out of copper. It also took a good day to complete.
If I bought another stove (that particular Vogelzang stove saw its last fire when some legs broke off while moving it), I might go with a Vogelzang stove again, but it would be with the fore knowledge that I would have to seal it up air tight. That is a good $75, but all total it would be a $475 investment not calculating in my time. A good airtight stove off the showroom floor around here is an easy $1200 and maybe more.
To me...it is worth it versus buying an airtight stove right out of the showroom for much more money. I say that because once air tight, they all work the same. A Vogelzang was not worthless, it just allowed air into the firebox, and a control a fire in one of two ways:
(1) By the amount of fuel (wood) put into it and allowed to burn (not so easy to do in a hand fed wood stove)
(2) Or by the amount of air allowed to consume the fuel
The Vogelzang Boxwood Stove is especially leaky on air because it has so many spots that are removable. (Yes I had one myself years ago). It can be made airtight, any stove can.
But there is no wrong answer here. A person who chooses to spend $2500 for a super air tight stove off the showroom floor is going to get a high performance wood stove without doing a thing to it, where as someone who wants to pay as little cash as possible can pick up a Vogelzang Stove at Tractor Supply, and spend a few hours making it air tight. As long as people knowing the latter know that up front, it is okay, but if they bought 2 cord and think they can get through a Maine winter with a stove you can practically chase a rat into, they might be a bit cold when they run out of wood around Christmas Time.
Note: I LOVE wood stoves, and have entertained the thought of having a stove rebuilding shop. But be that as it may, I am here to say that 9 out of 10 people on this forum have the skills to take a cheap wood stove and make it airtight with materials every hardware store has.
Not exactly an answer to your question, but there are other things to consider besides the quantity of wood you burn (although I grant you that is an important one).
I have heated with wood stoves for 40+ years, with a variety of wood stoves, from the cheap junk type to the more modern high efficiency type. Unfortunately I never switched from a low end (or even mid range) stove to an ultra efficient one in the same house, so I can't give you any good comparison numbers there. But I had switched from low end stoves to some of the mid ranges stoves (vermont castings of 30 yrs ago, good at the time). In those cases I recall maybe a 30-40% reduction in wood (but these are pretty old memories so take that into account).
I now have a high efficiency/low emissions stove (an Avalon) in a very well insulated house of fairly new construction. We burn 1/2 the wood I used to use in a smaller but older and less insulated house back with that Vermont Castings stove. But the bigger change that I think is worth mentioning is how cleanly this stove burns. With the older stoves, I had to clean the chimney of creosote at least once a year and sometimes more often, even with hot fires to "burn it out" and various additives. With this new stove I have found it only needs to be cleaned once every 4-5 years, and at that I typically get only a quart of creosote out of the 24' of chimney and stove pipe. It is just amazingly clean burning.
Not sure how you would factor how clean burning a stove is into how efficient a heater it is, but since all the burning is being done in the house to be heated, they should be related.
I couldn't put numbers on it, but a clean burning stove is turning more of the wood into heat and less into toxic chemicals. As long as that heat mostly stays inside the house and doesn't go straight up the chimney, you are getting more useful heat from the same wood.
It's funny how it's always an "apples to oranges" comparison on this type of subject. You can never get to apples in the same room!
My contribution is my father-in-law built his house within 2 years of us. So similar construction and insulation. But his house is almost a 3rd of the size - but he burns about a 3rd more wood in his old stove. We also have the soapstone hybrid stove.
However - this is apples and oranges because a) he keeps his house at least a few degrees hotter and b) iI carefully stack and cover my firewood (which I think gives you a better burn) and he just puts it in a big ol' pyramid pile until fall.
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