Guidance please. Replace Vigilant with Jotul?

[rudall]

Looking for guidance? I've heated with wood for decades here in Colorado.

We are in the mountains at 6800 feet: long cold generally sunny winters. Maybe 8000
degree days, something like that.

We are burning about 2.5 cords, maybe 3 max each year in a 70s VC Vigilant.
We like this stove, in general, it's been good to us, and I just
got done cleaning the passageways in the back. It could probably use fresh
caulking, but all in all it's in reasonable shape. (The house is 1600 sq feet, well insulated
passive solar.)

I was in a stove store today to check out their spring sale... Jotul has a
similar sized stove, the Oslo 500, or something like that that claims to be 72%
efficient. I'm trying to figure out how efficient our older stove is, and how much wood
I might save by getting a new one, Fed tax credit etc.

My (guess)timate is that the Vigilant is about 50%. If that's right, I might save nearly a cord
a year by upgrading.

Does upgrading make sense? Other thoughts?

 

[BrotherBart]

I can't tell you anything about either stove but I can tell you that we went from five to six cords a year to two and a half to three when we tossed our old beloved stove and installed the EPA stove.

 

[firefighterjake]

Don't know much about the Vigilant . . . love the Oslo . . . but honestly only burning 3 cords a year isn't really all that bad . . . I guess I would have to look at the cost of the new stove and decide if the savings in cutting/buying less wood would be worth it . . . of course there are other benefits as well such as cleaner burning, nice view of the fire, etc. . . . and then you also want to consider how many more years you expect this stove to last . . . as it is now, it sounds like it's in pretty good shape.

 

[Battenkiller]

or something like that that claims to be 72% efficient.

FYI, the EPA tests don't test for efficiency. Instead, they give stove types an arbitrarily determined default efficiency rating. Catalytic stoves are all rated at 72% and non-cats at 63%. Stoves claiming to have better efficiency than the EPA rating have to have independent laboratory testing for efficiency. Manufacturer claims of 63% or 72% efficiency indicate that they are using the EPA default figures and have never bothered to actually get the stove tested for efficiency.

I've looked for a long time to try to find anything to show just how these independent tests are conducted, and what exactly the rating means. It is very difficult to accurately measure the total average heat output of a stove, even in a controlled lab setting. Plus, the way it is reported may be true but meaningless. A given stove may be 81% efficient in combustion, but that doesn't say how much sensible heat the stove emits into the living space per unit mass of dry wood. And like most things of this nature, your mileage may vary by a lot from the stated efficiency.

I have a Vigilant and I find it to be pretty darn efficient at getting the heat that's inside the box out into the room. Anecdotally, there's a few folks posting here that have made the switch from the Vig to the Oslo. They seem to be happier with the less complicated regulation of the stove and claim to use less wood for the same amount of heat. I just got my Vigilant last season (excellent used condition), and I'm not about to invest over 2 grand to save a cord of wood a year. At 1 cord saved per year, it would take me at least 10 years to break even.

You are blessed with a lot of sun up there in the dry mountain air. 2 1/2 cord with the Vigilant compared to my almost five cord in the great Northeast. One of the local stove experts in my area who has extensive knowledge of, and has used both said, "If you burn 7 cord now, you might burn 6 1/2 with the Oslo." That may not be true for everybody, and he may be exaggerating to make a point. Still, I can't imagine any stove allowing you to go from 2 1/2 to 1 1/2 cord. Best you might save I'd guess at 1/2 cord per year. One thing nobody will dispute, however, is that it will be cleaner burning.

 

[fraxinus]

I went from a 70's Defiant to a Jotul F600 Firelight (next size up from Oslo) last fall. After a full season, I'm very glad I made the change. The Defiant and other early VC models were great stoves for their time, but no question you'll use less wood with a newer stove. A record mild winter makes exact calculation hard, but taking that into account as much as possible, I'd say I used 20% to 25% less wood. In your case, you have to weigh the expense of a new stove against the savings in wood - since you don't burn very much as it is, the payback might not be either quick or very extensive. The EPA efficiency comes at a price, too. Very dry wood is a necessity. The VC stoves are far more forgiving in that area. How important the reduced emissions in an Oslo may be to you is another factor. All in all, I think if I had been using only 2.5 cords per winter, I would not have seen the investment in a new stove as worthwhile.

 

[Todd]

Sounds like you aren't burning 24/7 going through 2.5 -3 cords? I'm willing to bet you will burn more firewood with the Jotul because you will like the look of the fire, turn into a fellow hearth.com geek and end up burning more often. :lol:

 

[Battenkiller]

The EPA efficiency comes at a price, too. Very dry wood is a necessity.

With all of the claims I read of very dry wood putting out twice the heat of marginal wood, could it be that the increased efficiency comes solely from burning drier wood?

 

[fraxinus]

The EPA efficiency comes at a price, too. Very dry wood is a necessity.

With all of the claims I read of very dry wood putting out twice the heat of marginal wood, could it be that the increased efficiency comes solely from burning drier wood?

I'm far from an expert, but I doubt if it's solely from drier wood, although that's undoubtably a part of it. When any wood is burned, a certain number of btu's go into boiling off the moisture rather than in usable heat. Old VC stoves with their 8" flue requirements and many air openings had a very powerful draft so could easily ignite and burn less than perfectly dry wood, but they were still using energy to convert moisture to vapor. Modern EPA stoves have a very restricted draft so getting iffy wood to ignite and stay burning isn't easy. Once these stoves reach a stack temperature of 350 to 400, the dryness of the wood seems much less critical. The calculation done by the Maine Forest Service involved wood kiln dried to less than 20% moisture content vs. wood seasoned for 9 months with a 45% moisture content, if I remember correctly. Any stove will be more efficient with dry wood, but the various designs employed in EPA stoves gain efficiency in other ways as well.

 

[begreen]

The additional efficiency and cleaner exhaust comes from burning off the wood gases that would normally head up the flue in a pre-EPA stove. There were some exceptions. For example, the Vigilant did this with an early version of secondary reburning.