which numbers to use to size a stove

[wisc harv]

All of these numbers are so confusing and I wish I knew all the numbers on my old stove but maybe with all those little tubes they have now you can't compare anyway!
So do you guys think it is better to go by the EPA hang tag or the manufactures numbers when it comes to BTU out put. We now have a Lopi 380-440 that is 22 years old and has done us pretty well, on the coldest days we could use a bit more but were worried about having one too big. We are browsing for a stove that is just a hair bigger. Our original hang tag says 6928-46,270 BTU/HR. We were looking at one that said the BTU’s were 60,000 and we thought that was what we wanted but the EPA numbers are lower then the ol’ Lopi…... a guy would hate to drop a bunch of money and find out that it was smaller then what we had, this is Wisconsin.

One other thing I have noticed is that the stoves have gotten wider and not as deep. I was told by a dealer that it was so we got more glass, but aren’t they harder to load? We load the Lopi sticking the wood in the long way not cross wise…. are there avalanche problems?? Our room isn’t laid out very well for a side door and even then it would have to be a right side door. Maybe it is just better to doctor up the lopi and stick with it.

 

[branchburner]

Best number: firebox size in cubic feet. That number is reality. The other numbers are fantasy.

 

[Wet1]

If you could give us some details about your house, I'm sure we could help with some recommendations. But BB is right, you need to look at Firebox size. Cat vs non cat makes a little difference as well.

 

[wisc harv]

Well, mid sized (maybe 1800sq ft) Midwestern farmhouse, out in the open, old windows with real storms, only attic insulation. 4 rooms down stairs and stairs for up stairs off center room. Stove goes in the parlor, north side double doors lead south into dinning room, bedroom off to west of that and kitchen at the south end of dining room, kitchen does have a Waterford Stanley cook stove (oh Stan he IS the man!! my dream stove) oops got carried away...:~). We had been kind of looking at the jotul black bear but are afraid it is too small, we like the look, the door layout, how the wood goes in ( non sideways), non cat and my husband thinks cast stoves last longer then the steel, the soap stones are so expensive and as i read on this site it seems like all you guys are saying that all stoves are junk in 20 years no matter what kind..... or am I reading that wrong??? do tell. The sales man I saw didn't seem like he was just too informed, couldn't get the door on the big jotul to close and didn't know why the black bear had 2 leavers.....The guy we bought the stanley from didn't even know waterford made a cook stove! I think they like to sell gas stoves. So fill me in. Are they all only going to last 20 years?? I'm starting to think that we should take the Lopi out and re fabricate a few parts and paint her up.....The new lopis don't seem as long lived as what we have. We have a 1906 Case steam engine, things should be made to last.

 

[Fsappo]

Best number: firebox size in cubic feet. That number is reality. The other numbers are fantasy.

Agree 100%. Also may want to consider if radiant or convection works best for you

 

[wisc harv]

Also may want to consider if radiant or convection works best for you


how do you figure that??

 

[Fsappo]

Well, other folks may not agree, but in my humble opinion:

I use radiant stoves to heat large open areas.
I use convection stoves when trying to heat multiple rooms or to creat huge amount of hot air to travel upstairs.

 

[wisc harv]

Thanks~I guess that would put me n the convection camp. If I am correct that is what the Lopi is

 

[Fsappo]

I think most of them are. They are also a fine stove. With how you described your home. I would look for something with a blower and about a 2.7-3 cubic foot firebox.

 

[Corey]

I'd also consider how you intend to use it. A smaller stove, burning hard is more efficient at 'keeping' a space warm - if you plan to burn 24x7. But if (like me) no one is home during the day so the fire goes out. You might opt for a bigger stove for more capacity to warm the space up faster.

 

[Highbeam]

There are several stoves currently being made that can be loaded the long ways like you desire. Many people like that. I have a side door and you can bet I use it to load logs the long way vs. throwing them up onto the side of a pile sideways.

Look for a 3 CF stove made of plate steel. You seem to like the plate steel and there are no problems with leaky seams.

 

[wisc harv]

We are pretty much 24/7 burners and I am usually here all the time. I have fan in the upper door corner which does wonders so i think I would skip the blower. Any idea how to compare a 20 year old stove to a new one?? and do they really wear out so quickly?

 

[Mr. Kelly]

I use the EPA figures as a manner of comparison, and to help clarify small differences in stoves. For example, you can have 2x stoves w. the exact same firebox size that produce different BTU ouputs. I would think this is due to design characteristics that will allow one to burn a little more efficiently than another. The EPA list helps compare these things.

Here is a link that has all current EPA certified stoves listed alphabetically. I use this list to compare performance of one stove to another. I think that's a safe bet.

(broken link removed to http://www.epa.gov/oecaerth/resources/publications/monitoring/caa/woodstoves/certifiedwood.pdf)

This is a .pdf file that is worth saving if you're shopping for stoves.

 

[CrappieKeith]

O good rule of thumb....40,000 btu's per 1000 s/f

 

[SmokingAndPoking]

The BTU outputs on the EPA certification page are just calculated from the estimated efficiency (63% for non-cats and 72% for cats) and the dry burn rate found during the Low Burn test and High Burn test. They aren't useful for comparing anything, other than the low and high dry burn rates attained during EPA testing.

Here is the formula from the EPA:

Estimated heat output in BTU/hr = Hv x (Est. Efficiency/100) x BR

Where:

Hv = Heating value of fuel (19,140 BTU/kg)

Est. Efficiency = 63 for non-cat and 72 for cat

BR = Burn rate of dry test fuel per hour (kg)


I said that to say, stick with the firebox volume as the most valuable tool for comparing stoves!

 

[fredarm]

I'd look at the Pacific Energy Alderlea T6. It's a cast iron stove with a steel firebox. So you sort of get the best of both worlds. You can also load it North-South like your old Lopi. PE stoves are easy to use and are very efficient. If the T6 looks like too much stove for you, look at the T5. It's a medium size stove, but you can still load it North-South.

 

[Mr. Kelly]

Not sure I understand this... if the EPA uses the same methodology to test each stove, and the conditions are comparable, why couldn't you use the findings as a measure of comparison???

 

[SmokingAndPoking]

Not sure I understand this... if the EPA uses the same methodology to test each stove, and the conditions are comparable, why couldn't you use the findings as a measure of comparison???

Case in point, from the EPA list:

VC Dutchwest Small Catalytic
Firebox Volume 1.6 cubic feet
BTU/hr Range EPA Test Method 7,800 to 26,800 BTU/hr

VC Dutchwest Extra Large Catalytic
Firebox Volume 2.9 cubic feet
BTU/hr Range EPA Test Method 10,500 to 27,700 BTU/hr

These are monstrously different stoves in the real world, yet the Extra Large is only rated 900 BTU/hr higher than the small. All based on high burn rate during the test procedure and nothing to do with actual heat output.

 

[wisc harv]

Thanks much, guess it is time to head back to the stores and look under the hood.

 

[Mr. Kelly]

Not sure I understand this... if the EPA uses the same methodology to test each stove, and the conditions are comparable, why couldn't you use the findings as a measure of comparison???

Case in point, from the EPA list:

VC Dutchwest Small Catalytic
Firebox Volume 1.6 cubic feet
BTU/hr Range EPA Test Method 7,800 to 26,800 BTU/hr

VC Dutchwest Extra Large Catalytic
Firebox Volume 2.9 cubic feet
BTU/hr Range EPA Test Method 10,500 to 27,700 BTU/hr

These are monstrously different stoves in the real world, yet the Extra Large is only rated 900 BTU/hr higher than the small. All based on high burn rate during the test procedure and nothing to do with actual heat output.

This makes me want to know more about the physics and chemistry of combustion. The question is... how much "hotter" does combustion get with the addition of more fuel? One thought is that more fuel would simply get the fire burning longer, but not necessarily considerably hotter. Does fire have a physical and chemical limit to how hot it can get? Upon first thought, this theory doesn't seem to make sense, given that a house fire should be considerably hotter than a camp fire, due to the volume of wood, but who knows, maybe not. A scientist would know this.

What's the point here? Well, maybe the fact that one box is bigger relates mostly to the length of the combustion, and not as much as to the heat output. This seem true if you look at quite a few of the EPA comparisons, which show many products that have boxes that are one step up, but get minimal amount of increase of BTUs.

Any thoughts? This may be worth a separate thread...

 

[Wet1]

I don't know that I'd agree with your husband regarding cast stoves lasting longer than steel. From a functionality and longevity standpoint, I'd take steel over cast iron, but cast iron often looks better.

Regarding stoves, having 1800 leaky sq ft with minimal insulation in WI, I'd be looking for a 3 to 3.5 cu ft firebox. If money is a concern (and it often is), I think you'd be hard pressed to beat the Englander 30-NC for around $1000 (Home Depot or Lowes), plus you can get the 30% tax credit with this stove. Anything else is going to cost you a lot more. The 30-NC is a very capable heater and well regarded around here. Consider it before you spend $2k+ for a stove that wont do anything more for you. The down side is it has to be loaded from the front, but that's a small price to pay for such a bargain.

Remember, your dealer is going to be tacking on 30% plus to whatever he is selling you, the box stores work on much smaller margins. (Sorry Frank, I'm sure this will touch a nerve with you). And while Englander doesn't have a local dealer to "service" you, the Englander guys are tops when it comes to customer service.

BTW, it's hard to say how long any stove will last, too many factors and variables.

 

[grommal]

Best number: firebox size in cubic feet. That number is reality. The other numbers are fantasy.

Absolutely true that firebox size is the number that rules. The practical efficiencies of modern stoves are pretty much the same, so more fuel means more heating ability. True stove efficency differences are minor by comparison to firebox size differences.

I'd guess that the least useful numbers for comparison are the BTU values. You've already seen some other examples posted here that confirm this.

The manufacturer claim for square feet of area heatable is maybe a little more reliable, since no stove manufacturer wants a bunch of irate customers who can't even get close to heating their 1500 sf house with a stove that says it can do 2000. I think these ratings can be used to get you in the right ballpark.

What I did was compare usable firebox size (by measuring it myself, since I found that different manufacturers must have very different definitions of how much space is usable) in order to compare heating capabilities of particular stoves. I used the sf heated area capacity as a guide to choosing the overall stove size, and hence which models to compare among manufacturers. As most folks here have recommended, err on the larger side if you can, so I "rounded up" to the next bigger stove than was really needed. The result is that I have a Jotul Oslo that has maybe a little more available horsepower than I really need, but is still sized so that it does not run me out of the house on shoulder season burning.

 

[MJR46]

How large is your home in sqft? I am considering a Jotul oslo and I have a 1388 sf ranch with the stove being installed at the far end in the family room ( where the chimney is) with a doorway and another opening into the LR.

 

[Mr. Kelly]

How large is your home in sqft? I am considering a Jotul oslo and I have a 1388 sf ranch with the stove being installed at the far end in the family room ( where the chimney is) with a doorway and another opening into the LR.

Hey... Here's my set up:

We have a 1600 sq. ft. house, on two levels. It's an antique-style saltbox farmhouse that is effectively a circle. The kitchen is in the back (north) with doors on each side. One door leads west to the top dining room (north), the other door runs east to a small pass-through. A south door from the pass-through leads to the "parlor", which runs on the east side of the house. At the south-west corner of that room is a door that leads to another pass-through that leads to the stairway, and then on to the south-east corner of the dining room, completing the circle. It's a pretty typical old farmhouse set up.

Our 3 cu.ft. Pacific Energy Summit is located in the south-west corner exterior walls of the dining room. Can you visualize??

Well, the heat, with some fanning, travels this circle fairly well. The room with the stove will get to about 80 degrees on average, when cranking, and the kitchen, and parlor will get to about 70. That's a pretty big difference between the rooms, but it's considerably better than when we had no stove (old house + oil burner = cold house).

On the down side, the heat WILL NOT penetrate into any of the other rooms that are off of this circle. There's an "add on" room to the north of the dining room, in direct sight of the stove, that has 3x small steps down to floor level, and the heat, even in a direct line, WILL NOT effectively enter and heat this room. Consequently, we have to keep the oil zone for that room active. Plus, there's another add-on room that is east of the kitchen pass-through. The heat WILL NOT effectively enter this room either, and we have to keep the heat on in that room.

The upstairs rooms catch some heat from radiating up through the floors, and likely from some heat rising up the stairs, but it's not balmy. Might get to about 62 degrees, tops.

So, that's our story.

Heat won't go down stairs, and it doesn't seem to want to go away from the "circle" of our house.

Even so, we enjoyed our stove for the first winter this past winter. It's a lot of work... I mean A LOT, but the warmth of the stove has changed the feel of our house tremendously. I wouldn't, in retrospect, get anything less of a stove than what we got. In our case... more is more!

Hope this helps! Cheers!

 

[stoveguy2esw]

mr kelly,

a little trick if you want to move heat into a room which simply wont heat up for you. place a small desktop fan just inside the doorway of the room you wish to heat (keep it kinda out of the traffic pattern if possible) here's the trick , aim the fan out of the cool room into the heated "circle", this will start moving cooler air from the floor into he heated space to be heated up as the rooms there normaly do. the removal of the cooler air down low will pull heated air into the room up high. a way to tell if its working without waiting, after setting up the fan and with the "circle" already warmed up , take a candle or ligter or lit match , hold it high in the doorway and watch the flame , if the flame leans into the cooler room the room should heat up.


to the OP, my opinion on sizing would be a combination of both firebox size as the members have stated , also look at stated square footage of heating capacity. remember now , in virtually every example you look at the number will be "best case" as not all areas of sq footage are created equal. degree of insulation and local climate are factors as well. for example, a 1K ft stove will not heat a 1K ft home in montana as well as it would heat the exact same 1K sq ft home in georgia simply because the outdoor tems are quite different.