Smaller, hotter fires?

[KJamesJR]

As some of you know I’m knew to burning this year, a rookie. I’m burning in an Oslo. I recently decided to do an experiment and by recently I mean tonight as I have some free time.

I decided to finally take all my splitting scraps in and see how the stove maintains heat throwing in a small handful of these thin, long scraps. Maybe 3 or 4 at a time every two hours or so. I must say I’m impressed.

I initially decided to do this to help burn down the coal bed and have some smaller drier material to get it going fast in the morning. Also up until now we haven’t been using any kindling so I thought it might be nice to have some.

About two hours in and the stove top is nearly at 500 from a cold 350. Mostly it’s been hanging around 450 for the past hour or so. Secondaries have been going well even after opening the door and adding more fuel. It’s not burning as fast as I thought it would and I’m leaving the air around 75% open. So naturally I’m also getting a strong primary burn.

Anyone else practice this method? I’m thinking it may be a more efficient way for us to heat during the day now. It catches very quickly and just keeps going vs raking coals around and packing it full. Waiting for your larger splits to catch and the stove to warm up before cutting it back.

I can’t help but feel mislead about long burn times being the gold standard. If you’re home, smaller hotter fires seem to be were the real efficiency is. I mean, the stove is nearly empty and it’s nearing 500 degrees as I type this.

 

[prezes13]

I truly think that the wood is the difference. Now you are burning drier wood at higher temperature. That’s why you are gettin hotter and more efficient burn(secondaries). The most efficient way of burning in a modern stove is a big load, but it has to be well seasoned wood.

 

[Das Jugghead]

As some of you know I’m knew to burning this year, a rookie. I’m burning in an Oslo. I recently decided to do an experiment and by recently I mean tonight as I have some free time.

I decided to finally take all my splitting scraps in and see how the stove maintains heat throwing in a small handful of these thin, long scraps. Maybe 3 or 4 at a time every two hours or so. I must say I’m impressed.

I initially decided to do this to help burn down the coal bed and have some smaller drier material to get it going fast in the morning. Also up until now we haven’t been using any kindling so I thought it might be nice to have some.

About two hours in and the stove top is nearly at 500 from a cold 350. Mostly it’s been hanging around 450 for the past hour or so. Secondaries have been going well even after opening the door and adding more fuel. It’s not burning as fast as I thought it would and I’m leaving the air around 75% open. So naturally I’m also getting a strong primary burn.

Anyone else practice this method? I’m thinking it may be a more efficient way for us to heat during the day now. It catches very quickly and just keeps going vs raking coals around and packing it full. Waiting for your larger splits to catch and the stove to warm up before cutting it back.

I can’t help but feel mislead about long burn times being the gold standard. If you’re home, smaller hotter fires seem to be were the real efficiency is. I mean, the stove is nearly empty and it’s nearing 500 degrees as I type this.

This is interesting. I am learning the ins and outs of my first EPA stove. I have a Pleasant Hearth 1247 wood stove and one of the reasons I bought this was it was advertised as having a 6-8 hour burn time. This claim is as far from reality as the East is from the West. I average about two hour of actual burn and maybe another hour of decent heat after which there is a good bed of coals that will last another 3-4 hours but produce essentially no effective heat. I work mostly from home during the winter so I am able to feed the stove every few hours but here on the site I read that the stove is intended to burn a full load down to coals before reloading. By reloading every couple of hours I end up creating a very large bed of coals and ash. I recently picked up a slotted stainless steel serving spoon to use to sift ash and coal on the fly and I will see if that helps at all.

I know from experience that larger pieces of wood will burn slower but I am dealing with wet wood (primarily birch and oak felled and split over the summer) so that is having a significant impact on stove performance. Next season should be better and I am eager to be able to compare notes from this season with next season. For the time I am splitting my wood into smaller splits in order to create more surface area and burn cleaner. What is the size of the long thin scraps you are using? Are you experiencing a build up of coals and ash?

 

[EatenByLimestone]

The wet wood seems like your problem, Das Jughead.


To the OP, if you let the ash build up, or add a layer of fire brick to the bottom of the stove, you'll keep the secondary action and high temps with the primary air cut back. The key is lifting the fire up toward the secondaries to keep the top of the fire box hot.

 

[prezes13]

Exactly dry wood is a key. Burning wet wood in a modern stove is like pulling teeth. Not pleasant. But when you have properly seasoned wood it is all peaches and cream.

 

[Ashful]

I can’t help but feel mislead about long burn times being the gold standard. If you’re home, smaller hotter fires seem to be were the real efficiency is. I mean, the stove is nearly empty and it’s nearing 500 degrees as I type this.

When giving advice, we all speak from our own perspective. Other than holidays and sick days, I am likely home to feed a stove in this fashion less than once per year. So, don’t feel mislead about the importance of long burn times, we were genuine when giving that advice, but it may not apply to you if you never have any need to be away from the house. We all have different constraints, and most make assumptions that others are in a situation similar to their own.

 

[KJamesJR]

Don't get me wrong, I'm not implying that long burn times are irrelevant. However there's more to efficiency than an 8 - 10 hour burn. I started the season with very dry, well seasoned wood. It burned great and I saw stove top temps at +500 degrees for several hours on a full load with primary air nearly closed. I've been getting close to those same results on scraps, maybe a 25% load with primary air at 75%.

Ashful, I'm not saying I don't heed the advice given here. I built my entire system from the advice given here and am 100% satisfied with the results. I admire long burns just as much as the next wood hoarder. I pack it twice a day for the long burns but in the "in-between hours", from when I get home from work to before I go to sleep, I can keep the house nice and toasty with less wood, or so it seems.

As for DasJuggheads question, the scraps I'm using are long thin pieces left over from hand splitting. glancing strikes or pulling apart knots. They're about 22" long and anywhere from 1/8" - 3/4" thick. I pulled these pieces directly from the snow outside and just threw them on the hot coals in the stove. So I wouldn't say they're completely dry. At least the first load wasn't until I brought the rest in. Over the course of four hours, about three loads ( handfuls) the coal bed had turned to ash and the room was 70 degrees, below freezing outside. Before going to bed I loaded it with ash, got it going pretty good and dialed the air down for the long burn.

All I can say is try it out.

 

[Ashful]

I actually do something similar in the evening hours, on colder days. I rake out the coal bed when I get home from work and throw three medium splits, or two large, on top. I run the stove wide open (BK = thermostat = no overfire) to burn down the coals while extracting some quick and big BTU’s from that one-third-sized load. Four hours later, it’s down to just coals, and I do the overnight reload. In my case, I believe the efficiency when running on high (80% HHV) is not nearly as good as the efficiency at lower settings (86% LHV), but it does the job when I need big BTU’s to drive this cave up by as much as 1F per hour.

 

[Das Jugghead]

Temps here are supposed to drop into the single digits Saturday and then below zero on Sunday so I will try out burning my smaller splits and see how that goes.

 

[KJamesJR]

Well the wife burned up all my little splits today. Looks like my experiment is over until I can split up more. Supposed to be a big blizzard coming in just a couple of days so I don’t see myself having time to split more either.

 

[Adabiviak]

Anyone else practice this method?

I do, but mostly because I'm loathe to throw away these "tiny uglies", as opposed to their qualifications for making a good fire. By the time they're produced (slop from splitting), they've gone through much of my rotation cycle for wood (several years), and is otherwise fantastic... couldn't imagine throwing it away.

 

[Easy Livin’ 3000]

I agree with your theory, at least in my stove. I think a fully packed stove sends more BTUs out the chimney than smaller loads. The long burn times are important for overnight and while at work, plus sometimes it's just nice to take a break from loading. Burning 24-7 from November through April means lots of loading, and if the interval is longer, it's less tedious.

 

[maple1]

Well the wife burned up all my little splits today. Looks like my experiment is over until I can split up more. Supposed to be a big blizzard coming in just a couple of days so I don’t see myself having time to split more either.

Get some big 45 gallon garbage cans on wheels, for next year. Get it all in them before snow flies & wheel them inside.

I have one, full, from when I put my wood in in the fall. Mostly bark. Haven't gotten into it yet. But almost ready to.

 

[charger4406]

Get some big 45 gallon garbage cans on wheels

A cheaper, all be it heavier way is to use old 50lb dog food or feed bags and fill them with the scraps from splitting
as this is what I do, but I like the garbage can idea, easier on the back.

 

[Dug8498]

I truly think that the wood is the difference. Now you are burning drier wood at higher temperature. That’s why you are gettin hotter and more efficient burn(secondaries). The most efficient way of burning in a modern stove is a big load, but it has to be well seasoned wood.

Bingo!


Sent from my iPhone using Tapatalk

 

[jatoxico]

I started a thread a couple years ago about heating my house for a weekend off the branches and leftovers I found in my yard and woods. Stuff most would bundle and put to the curb.

I was impressed with what I was able to accomplish with scrap so I then processed an estimated 1/4 cord of small branches etc and bagged it in seed bags to dry. Was tremendous to have all that kindling to start fires, burn down coals and heat.

Not to bury the lead but I feed my fire a little at a time, all the time assuming I need the heat. I disagree that full loads is most efficient. Full loads have a start up that smokes and a cool down. Smoke equals poor efficiency not to mention a cold stove that's not heating. IMO it's more efficient to get the stove to the temp that supports secondary combustion and keep it there just like other systems (eg. pellet stove, ICE's, oil burner etc).

With small wood I can keep my stove in a narrow optimum temp window without building up excessive coals. Of course I burn in cycles when I'm not going to be around or if I simply don't need the heat. But if I'm there to do it, I load to keep my stove hot enough to support the secondaries without going too hot which loses more heat up the stack and sometimes creates too much temp swing.

 

[Ludlow]

I put in a log or two at a time. I got the stove so I could play with it.

 

[KJamesJR]

Full loads have a start up that smokes and a cool down. Smoke equals poor efficiency not to mention a cold stove that's not heating. IMO it's more efficient to get the stove to the temp that supports secondary combustion and keep it there just like other systems (eg. pellet stove, ICE's, oil burner etc).

With small wood I can keep my stove in a narrow optimum temp window without building up excessive coals. Of course I burn in cycles when I'm not going to be around or if I simply don't need the heat. But if I'm there to do it, I load to keep my stove hot enough to support the secondaries without going too hot which loses more heat up the stack and sometimes creates too much temp swing.

This was the message I was trying to convey in my original post. Keeping the stove in the optimal burn zone by not allowing it to cool. I was having great results with heat output on scraps and didn't have to worry about an oversized coal bed. Would I want to do this all the time? No because I'm barely ever home. However it's food for thought for those who are kicking around the house and can get to the stove every two hours or so.

 

[SpaceBus]

This is exactly why we have a smaller stove. It works well when just feeding it a few splits every hour or so. I can also run it on a 4-6 hour cycle, which I do when we leave or go to bed. This also keeps the house just as warm. It does have a slower startup to run a full load, but I don't have to mess with it for a while. It's all about what you need the stove to do.

 

[yooper08]

Agreed. Smaller, hotter fires will help with regulating temperatures in a tighter range (both stove and room) and tend to be more efficient. Producing too many BTUs at once is not an efficient use of them, so they can be considered at least partially wasted.

There is a minimum BTU production point though as you need to create enough BTUs to make heat for the room but also maintain flue temps above creosote production levels in the entire stack. This doesn't necessarily translate into stove temps as you can have hot temps near the fire, but as the flue gases rise, BTUs are lost to warming/keeping warm the stack. Not enough BTUs going up will cause flue gases to cool too quickly before exiting. I imagine most of us are above those levels, but just something to think about.

 

[SpaceBus]

I agree tho, full stove loads at a time can't possibly be more efficient. Heating the stove as quickly as possible and keeping it hot seems better. This is why folks like big cat stoves, and I don't blame them.

 

[yooper08]

In an EPA study on wood stove efficiency I read awhile back, it determined (IIRC) that the most efficient load is a firebox 2/3 full. I'll have to see if I can find it again to double check that.

 

[SpaceBus]

In an EPA study on wood stove efficiency I read awhile back, it determined (IIRC) that the most efficient load is a firebox 2/3 full. I'll have to see if I can find it again to double check that.

That's probably the most mine ever gets loaded anyway due to the secondary air inlets on my stove. On a top down load I get it as full as I possibly can, but there is still probably more room that I don't feel like chasing.

 

[Easy Livin’ 3000]

In an EPA study on wood stove efficiency I read awhile back, it determined (IIRC) that the most efficient load is a firebox 2/3 full. I'll have to see if I can find it again to double check that.

That sounds about right, based on my completely unscientific observations.

Just takes too much to get a stuffed box up to temperature without a lot of unburnt BTUs going up the flue. Plus, less space for oxygen.

 

[yooper08]

Just takes too much to get a stuffed box up to temperature without a lot of unburnt BTUs going up the flue.

For the times I have stuff it full, I'll roll up a couple of sheets of newspaper just to kick start everything. It provides a quick hit of heat to the firebox, plus burns that smoke to kick start secondaries, which allows me to shut it down sooner. Works pretty well.