Real world burn rate - splits per hour?

[Amin1992]

Hey guys, curious on this one. It's my first year with a wood stove and now that we're into deep winter my draft is definitely stronger, and as a result I'm burning wood faster.

I know this varies all over the map. But even with different species, different outdoor temps, NS or EW placement, and different sizes of logs (from 2.5" to 6" diameter) I'm getting generally the same burn times.

Best case, I'm getting a burn rate of 0.8 splits per hour. Worst case, I'm at 1.5 splits per hour.

Either way this feels like it's too fast. Am I wrong or is this normal?

I'm starting the clock the moment I get the fire going with kindling, and stopping it when the flame disappears and I'm down to hot coals.

I'm calculating this by just dividing out the splits I throw in by the hours it burns (for example, burned 5 splits in 3 hours today, so 1.6 splits per hour).

Is that normal? This is with the air dampened all the way down, and no blower on.

I constantly hear of guys getting 8 to 10 hour burn times and I just don't get how that's possible!

Thanks all

 

[rwhite]

How big is a split? How long is a rope? What stove and set up do you have? What specie of wood?

 

[Amin1992]

How big is a split? How long is a rope? What stove and set up do you have? What specie of wood?

Hey pal thanks for commenting. Like I said, it doesn't seem to have a meaningful difference for me. I get about 0.8 splits/hr with splits that are just 3" thick, and 1.5 splits/hr with 5" splits.

 

[bholler]

Anywhere from about one split an hour to one every 5 hours

 

[Highbeam]

I constantly hear of guys getting 8 to 10 hour burn times and I just don't get how that's possible!

What you're running into is that people define burn time differently. I got 20 hours of active 500 degree plus cat time from 5 big doug fir splits yesterday but that's in a cat stove running nice and slow. These guys getting 8-10 hours in a 2 cubic foot non cat stove like yours are generally measuring that from first spark to the last possible little coal that would allow restart without matches. I did it for years with a 2.3 CF hearthstone, barely made it through the night but most of the action was done in 5 hours at low.

My noncat 3.5 CF stove can burn a full load of 10 or so splits in 3 hours, load after load. However, if I let those little coals dwindle down to near nothing it might be 5 hours which is a significant difference.

 

[Dix]

Your insert has a 2 CF firebox, similar to my PE.

Max burn time, 6-7 hours from when my fan kicks on. Heat output for 7-9 hours. Maybe 2 hours after that before the temp starts to drop in the house. At that point, I can still fire off from coals, and be up & running with in an hour.

 

[Amin1992]

Thanks all for advice. Can I ask, what's your rate in splits per hour? From start to coals?

 

[SpaceBus]

Most people are not timing based on splits per hour. There's too much difference in stove operation, wood density, and chimney height between users to get something meaningful.

 

[xman23]

I never paid much attention to it. My wife said, on cold winter days, she uses 25 splits a day. Mine are large.

 

[Sawset]

A burn rate of 1cm/hr, I read that somewhere. There is probably no truth to that in the real world because of all the variables, but I do think of that every so often. A 5" block, banked to the back of the stove, with a nice layer of ash under it, here will last about that, 12hrs with a nice wad of coals left over, so close in that case. Most of the time though I don't have square blocks to wedge together, so mileage generally varies. But on very cold nights, when I actually care, I'll locate the largest rounds of locust for just that purpose.

 

[rwhite]

I would consider increasing your split size as well. 3" is in kindling territory. I usually split between 6-8". Anything smaller I leave alone and dont split at all. I will also split a piece or two down to 2-3" when i reload. This is just to fill in the gaps and pack as full as possible.

 

[Dix]

Splits per hour does not compute. To many variables.

Burns per hour computes, with variables.

You will burn wood faster in winter than spring & fall.

Are you letting the stove cycle through it's burn times, or just constantly feeding it?

 

[BigJ273]

Way too many variables...types of wood, size of splits, dryness of wood, etc. no way to accurately compile info based on “number of splits per hour”

 

[chipsoflyin]

1/2 split per hour,ash ,6inch split, 250-550-250 stove top

 

[Grizzerbear]

Too many variables and opinions of burn time meaning. To me its however long the stove is putting out meaningful heat. Usually from when my blower kicks on to when stove temp gets back down to 200 are counted as burn time for me because even at 250 the stove will keep my tiny house warm. With a bigger house though this would be different obviously and I would be reloading faster. Stove cf/house size is yet another variable if you look at it this way.

 

[Rickb]

my splits are all 2.5 - 4 inch splits. and I can load 3 splits in my cold stove and burn on high till its up to temp and shut it down and have a hot stove for 3 - 4 hours after... I can load 3 splits after that while the stove is still warm and leave it on high till im back into the right temp range and burn for another 4 - 6 hours. I have never really loaded the stove full because I have never needed that much heat.

Even when its below zero out I only load twice or 3 times a day on weekends. during the weeks days I load up at 2-4pm when I get home from work and Its still warm when the wife goes to bed at midnight - 2am.

 

[FPX Dude]

It's all about how much you can stuff in there, depending upon what is needed. Other than that, longer burns are because of bigger firebox, and thus, longer burn times.

 

[mar13]

In hiking long trails, there's a saying, "Hike your own hike." Basically hike how far and fast/slow you like to hike and stop comparing yourself to others or basing your choices off of what others do. I'm beginning to learn this can apply to wood burning as well. After reading hearth.com (too frequently?) I began to think how long of a burn should I get? When should I add wood? etc. I'm now relaxing more as I develop my own style and just burning how it feels right for my own wood, stove , lifestyle, house etc. (Admittedly I've even recently also mentally calculated what is my own typical split/hour rate.) So perhaps we could have some equivalent saying such as burn your own burn=BYOB? I'd like to add, however, this site has been invaluable in helping me develop my own style in an educated way.

Just don't burn smoldering fires if I live downwind of you!

 

[rosem]

If you have a modern EPA stove you get the most "value" packing it to the gills while it's hot and utilizing the secondary burns.

You'll go through a lot just throwing a few splits on at a time.

 

[moresnow]

Hey guys, curious on this one. It's my first year with a wood stove and now that we're into deep winter my draft is definitely stronger, and as a result I'm burning wood faster.

I know this varies all over the map. But even with different species, different outdoor temps, NS or EW placement, and different sizes of logs (from 2.5" to 6" diameter) I'm getting generally the same burn times.

Best case, I'm getting a burn rate of 0.8 splits per hour. Worst case, I'm at 1.5 splits per hour.

Either way this feels like it's too fast. Am I wrong or is this normal?

I'm starting the clock the moment I get the fire going with kindling, and stopping it when the flame disappears and I'm down to hot coals.

I'm calculating this by just dividing out the splits I throw in by the hours it burns (for example, burned 5 splits in 3 hours today, so 1.6 splits per hour).

Is that normal? This is with the air dampened all the way down, and no blower on.

I constantly hear of guys getting 8 to 10 hour burn times and I just don't get how that's possible!

Thanks all

Getting a 8 to 10 hour burn means completely loading the stove for the duration. Get the load hot and close down the air to the setups happy spot. A batch burn so to speak without opening the loading door until the load is gone.

It sounds as if you are opening the stove to toss in a split at close intervals? That won't get you any decent burn duration for comparison. Unless I misunderstand your description.

 

[rosem]

Also, are you going off of stove top temps or visual logs burning for this calculation?

I count a burn as the time my stove is above 300F. If some logs burn out and the stove is still at 600F I don't care.

 

[St. Coemgen]

Personally, my stove manual stated the stove at nominal output (that is, consistent output, so ignoring startup and cooling times) would consume 2.3 kg of wood an hour. And I have found that to be accurate. And since different woods, for example pine versus oak, weight different for the same volume of wood I can stick into the firebox, how often I load (i.e. burn times) depends on the wood I use (assuming equal packing of the wood each time of course). And the amount of air flow will certainly alter the burn time (either by the draft, or how you pack your wood). So weight, not "splits", and burn time is a better measure. And Burn times may be now be shorter if you have better draft -- and modern EPA non-cat stoves will not let you damp down the stove as much as older stoves. Maybe start to weight your wood, then use this calculator to see if your results vary :

Burn time calculator

www.hearth.com

 

[Nate R]

lbs/hr would at least get you closer to comparing things. But would require more math/logging.

I'm not sure how much wood I'll use in my place I'm building, so I'm thinking of logging approx MC and weight (bath scale or something) lf each "load" of firewood that gets brought inside. Add in the temperature logging I'm doing, and I'll have a rough handle on how much wood I need for a year, or for a weekend at my cabin if the temps are X.

This at least helps eliminate differences in split size and wood species/density.

 

[Sawset]

I know this varies all over the map. But even with different species, different outdoor temps, NS or EW placement, and different sizes of logs (from 2.5" to 6" diameter) I'm getting generally the same burn times.
Best case, I'm getting a burn rate of 0.8 splits per hour. Worst case, I'm at 1.5 splits per hour.

If you're messing around with numbers - after a while most just let it go, but as long as you're at it:
Another comparison could be, if you had a forced air furnace running, and then your stove running, crunch a few numbers and see if there is a correlation.
my 80k btu furnace, running 15min out of every hour, 75%eff, would be 15k btu /hr.
my stove, wood at 5000btu/lb, 5lb/split, 70%eff, to produce same as above would be around .8 split/hr.

or, some more numbers,
If you had a 4.3cuft box, 80lb of wood, 90%eff, in 20hrs that would be, around 18k btu/hr, or around .8 split/hr
same burn rate, more heat

 

[thunderhead]

Personally, my stove manual stated the stove at nominal output (that is, consistent output, so ignoring startup and cooling times) would consume 2.3 kg of wood an hour. And I have found that to be accurate.

Same here. I've done the math a couple different ways, and always come out to the same thing. 5 pounds per hour of wood at ~20% MC keeps my stove(new PE t5) cruising at a typical pace(STT of 500F averaged across the burn cycle) and my house around 72F during average winter conditions. This works out to be around 6kw, or about 20k btu/hr into the house, I assume 70% efficiency, so a couple kilowatts are going up the pipe/evaporating water.