Stove Ops & Burn Time

[yooper08]

This has been my first season with a true wood heater (not counting the fireplace its in - and the BK guys bound to comment, yes I know, everything less is not a true heater ), I've got this down pat for the most part but have a question. What I'm experiencing is that regardless of how much wood I put in, I don't get a drastically different burn time. Lately I've been putting in 4-6 splits and getting 5+ hours out of them. If I try to load it up, I don't get a drastically different burn time, what seems like 5.5-6 hrs, maybe a little longer if I let the room temp drops a little - I'll say this, its rare to go 7 hours. The big difference is how warm the room gets.

My question is, for a 2.3 cuft firebox does this seem about right, and if not what can I do differently? Theoretically I should be getting closer to 7-8 hours when full, even per SBI. Here's how I typically run the stove.

1. Load with new charge (turn off fan if on)
   
2. Monitor, able to damp down to half in 5-10 minutes (depending on cold/hot start)
3. Turn on fan (usually here, sometimes after Step 4 depending on temp reading from IR gun - like to see 350-400)
   
4. Wait a few more minutes until I can damp down further, usually this ends up at 0.25-0.5" from fully closed
5. Towards the end of the coaling stage, open it up to burn them down further and get air flowing to start the new load

Wood is a mix of cherry, oak, and ash (ash is now starting to transition to soft maple). I understand that if I were to load it full of oak, I'd more than likely get to the 7-8 hr mark, but that's not really what I'm asking.

Thoughts/input? Not trying to knock the stove, just wondering if there's something I could do differently.

 

[webby3650]

If you are able to get within an hour or so of the published burn time with a non-cat then I'd say your on track. 5 pieces of wood won't have active flames for all that long. Often, with a non cat the only way to really regulate heat output is with the amount of wood put into it. They have 2 outputs, hot and hotter! Again, not always the case, but often..

 

[prezes13]

All depends on temp outside size of the house etc. I get anywhere from 4 to 10 hrs burn time from my cape cod insert. 10 hours to me means the fan is still on and I can get a new load going relatively easy. At that point stove top temp measured with IR gun is about 150-180

 

[Woodsplitter67]

It sounds like your running the stove right The type of wood your putting has everything to do with burn time and the heat you get out of it. The wood is what drives the stove. You cant expect the stove to put out alot of heat or burn along time if that is past the capability of the wood your putting in. I also have a 2.3 cuft fire box and i regularly get 10+ hours of burn with all oak in the box and the stove temp is still 250 to 300. If i do all cherry the stove is almost out and its like 125/150. Same stove, same run, different outcome because of the different wood.

 

[iron]

load the wood east-west for longer burns?

 

[yooper08]

load the wood east-west for longer burns?

That doesn't seem to have much impact, which I'm trying to wrap my head around still. I'll load the longer stuff EW, but definitely prefer NS. The typical load actually looks like this: coals raked forward, one split EW in the back, then NS on top of that, then if I have anything that doesn't fit NS and I still have room, it goes EW on top of the NS. Once in awhile I'll load everything in one orientation.

It sounds like your running the stove right The type of wood your putting has everything to do with burn time and the heat you get out of it. The wood is what drives the stove. You cant expect the stove to put out alot of heat or burn along time if that is past the capability of the wood your putting in. I also have a 2.3 cuft fire box and i regularly get 10+ hours of burn with all oak in the box and the stove temp is still 250 to 300. If i do all cherry the stove is almost out and its like 125/150. Same stove, same run, different outcome because of the different wood.

Yeah, I get I'll get longer burn times with splits of oak vs ash. What I'm trying to wrap my head around is, with the same type of mix, whether I add 4-5 or 8-9 splits, I don't necessarily get that much longer burn time, just that much higher BTU output over just a slightly longer time. Just trying to get a feel if that's what I should expect or if there are tricks to extracting the BTUs over a longer period of time besides getting a quantum physics-based BK. I knew I could control BTU output with load size, I just assumed that burn time would be more in line as well.

Not complaining about burn times, just seeing if there's anything I'm missing.

 

[HisTreeNut]

I have a non-cat Buck...94NC. I find I get 4-7 hours of burn time depending on the mix, with another 1-3 hours of heat from the coals. I have a large firebox but never stuff it full until we go to bed because it cooks us out.
Put oak and maple in it last night about 2:00am, and had a fair amount of coals at 8:00am this morning.
When I load it full, I get it burning well, then crank the air back in stages. About 3/4 of the way is the magic spot. I have to play with the air to keep getting heat off the coals but that's all good...for me anyway.
Sounds like you are doing everything the way you ought to be.
I also will go north-south on the bottom, then east-west on the next layer. If the splits are small, I will do a 3rd layer north-south. Maybe that will help get a little more time from it.

 

[Woodsplitter67]

What about a thicker split..

 

[EatenByLimestone]

How tall is the chimney? You're starting to damp down after 10 minutes on a cold stove?

 

[yooper08]

Chimney is nearly 27 feet and insulated. Yes, I can typically start damping down around 10 min after getting the kindling going well on a top down start. Granted this can fluctuate a tad considering inside-outside temps and impact on draft strength, but my normal procedure is to light, make sure it gets going, close it up and ask Siri to set a timer for 10 minutes if I'm stepping away. If it's a reload, I'll ask for 5 min.

 

[yooper08]

What about a thicker split..

I've considered this. I'd say most of my splits are mid sized. I'll have to work through a section of the stacks to get to some larger stuff towards the bottom and see.

Also, thanks all for input so far.

 

[webby3650]

I have a non-cat Buck...94NC. I find I get 4-7 hours of burn time depending on the mix, with another 1-3 hours of heat from the coals. I have a large firebox but never stuff it full until we go to bed because it cooks us out.
Put oak and maple in it last night about 2:00am, and had a fair amount of coals at 8:00am this morning.
When I load it full, I get it burning well, then crank the air back in stages. About 3/4 of the way is the magic spot. I have to play with the air to keep getting heat off the coals but that's all good...for me anyway.
Sounds like you are doing everything the way you ought to be.
I also will go north-south on the bottom, then east-west on the next layer. If the splits are small, I will do a 3rd layer north-south. Maybe that will help get a little more time from it.

Cris crossing your wood like that will most definitely make a hotter fire. To extend burn times you want to stack your wood in there tightly, front to back. You want your wood to be consumed from front to back, rather than all at once.

 

[HisTreeNut]

Cris crossing your wood like that will most definitely make a hotter fire. To extend burn times you want to stack your wood in there tightly, front to back. You want your wood to be consumed from front to back, rather than all at once.

Whoops! Left that part out stacking it tight...thanks! Even with a criss-cross I stack tight. Did it loosely once...let's just say the Den was pushing 90. Glad the wifey was in bed, sound asleep...glad I had read some threads about what to do in an over-fire situation...glad I was wearing brown pants... .

 

[WoodyIsGoody]

My question is, for a 2.3 cuft firebox does this seem about right, and if not what can I do differently? Theoretically I should be getting closer to 7-8 hours when full, even per SBI. Here's how I typically run the stove.

1. Load with new charge (turn off fan if on)
   
2. Monitor, able to damp down to half in 5-10 minutes (depending on cold/hot start)
3. Turn on fan (usually here, sometimes after Step 4 depending on temp reading from IR gun - like to see 350-400)
   
4. Wait a few more minutes until I can damp down further, usually this ends up at 0.25-0.5" from fully closed
5. Towards the end of the coaling stage, open it up to burn them down further and get air flowing to start the new load

Sounds like you have a strong draft. Without being familiar with your insert I have a couple of thoughts:

1) Modern EPA stoves don't have a "fully closed" position. When the air supply is turned as low as possible it's still open a bit. Since you are not closing the air all the way I'm guessing this is to keep it hot enough to burn cleanly? If your wood isn't well seasoned you may be able to reduce the air supply all the way with more seasoned wood which could provide longer burn times.

2) Have you done the dollar bill test on the door gasket?

3) It sounds like you keep the fan running. This cools the stove which requires more air to maintain good combustion which shortens burn times. Of course turning off the fan might not be the best solution since it's an insert. Depending upon the installation you might lose more heat up the chimney and through the masonry than you transfer to the room.

 

[EatenByLimestone]

Chimney is nearly 27 feet and insulated. Yes, I can typically start damping down around 10 min after getting the kindling going well on a top down start. Granted this can fluctuate a tad considering inside-outside temps and impact on draft strength, but my normal procedure is to light, make sure it gets going, close it up and ask Siri to set a timer for 10 minutes if I'm stepping away. If it's a reload, I'll ask for 5 min.

I think draft might be a prime culpret to shorter burn times. it would be hard to try a key damper on an insert. Maybe a small ball of all foil closing up secondary air might help some.

 

[Chimney Smoke]

If you can fit 8-9 splits in a 2.3 firebox I think that's the problem. I have the same size stove and a full load for me is 6-7 splits max.

 

[CentralVAWoodHeat]

I experience the same thing with my stove. It is a smaller firebox than what you have but burn times don't change much based on how tightly I pack it and instead are more related to the wood used. It sounds like what you are doing is correct. I've found what works for me, if I have the time, is to use less wood per load and simply load more often. It consumes less wood and keeps the house temperatures more steady.

 

[Blazing]

Fans kill burn times...

 

[yooper08]

I experience the same thing with my stove. It is a smaller firebox than what you have but burn times don't change much based on how tightly I pack it and instead are more related to the wood used. It sounds like what you are doing is correct. I've found what works for me, if I have the time, is to use less wood per load and simply load more often. It consumes less wood and keeps the house temperatures more steady.

Yeah, that's what I'm trying to figure out and wrap my head around, the fact that I can burn just about as long with a smaller load as I can with a larger load. So the question in my mind becomes exactly what you stated, why fill it up since I'm home all the time - unless I need the extra BTUs now.

 

[yooper08]

Fans kill burn times...

I keep hearing that but haven't quite figured that one out, at least with my setup. First it's an insert and in the basement, so the fan's going to run. Second, I'm essentially closing it all the way anyway. Third, fan doesn't change draft performance, which is really the engine to all of this.

If we're talking about how long the coals can last, maybe? But I'm reloading when there's not many coals left - just enough to start up again. At that point, the front of the insert is about 280*.

 

[yooper08]

Sounds like you have a strong draft. Without being familiar with your insert I have a couple of thoughts:

1) Modern EPA stoves don't have a "fully closed" position. When the air supply is turned as low as possible it's still open a bit. Since you are not closing the air all the way I'm guessing this is to keep it hot enough to burn cleanly? If your wood isn't well seasoned you may be able to reduce the air supply all the way with more seasoned wood which could provide longer burn times.

2) Have you done the dollar bill test on the door gasket?

3) It sounds like you keep the fan running. This cools the stove which requires more air to maintain good combustion which shortens burn times. Of course turning off the fan might not be the best solution since it's an insert. Depending upon the installation you might lose more heat up the chimney and through the masonry than you transfer to the room.

1) Understand that one - fully closed is the air control is fully pushed in.
2) Good question, not lately - may need to adjust the assembly there, I'll have to check this once it cools off
3) I do leave the fan on, but once it's cruising there's hardly any room to damp it down further - 1/4" at best probably (I know that differs from what I said earlier about .25-.5") - would I really get that much out of the burn closing it down that little bit more?

 

[Blazing]

I keep hearing that but haven't quite figured that one out, at least with my setup. First it's an insert and in the basement, so the fan's going to run. Second, I'm essentially closing it all the way anyway. Third, fan doesn't change draft performance, which is really the engine to all of this.

If we're talking about how long the coals can last, maybe? But I'm reloading when there's not many coals left - just enough to start up again. At that point, the front of the insert is about 280*.

The fan will strip heat off either causing lower stove temperature or a need to run a higher draft to maintain temperature. The fan will cut my burn times almost in half to maintain a safe burning temperature.

 

[Hogwildz]

level the coals out rather than pull them all forward in a pile. Then stuff it full with large splits, fill in on top of the larges with mediums or smalls, if you have room. You'll get some longer times. North to south is how it gets burnt here.

 

[bholler]

The fan will strip heat off either causing lower stove temperature or a need to run a higher draft to maintain temperature. The fan will cut my burn times almost in half to maintain a safe burning temperature.

Yes but that is because you are opening up the draft to keep the temps up he is not he has it closed down all the way with the fan on or off so it will not effect the burn time. Also Idont find that split size effects burn time much for me either. I split small but because of that I can pack the stove really tight and fit in more weight of wood which actually gives me longer burns than if I load fewer big splits with more air space around them. The fact is that different things work for different people with their setup. Everyone needs to find what works for them.

 

[new home neil]

Be sure to check and see if you have another draft control, I run an enerzone wood stove and it has a second draft control. Once I found it it has increased my burn times significantly. Mine is in the basement with a long chimney as well.