small loads in a big stove

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Ashful

Minister of Fire
Mar 7, 2012
19,921
Philadelphia
It's plenty big enough for heating 850 sq ft. You may find yourself running partial, 4 split loads in milder weather. Just be sure that the wood is fully seasoned.
I see the advice of running small loads in a big stove come up often enough on this forum, either in milder weather, or because the stove is just too big for the house. But I wonder how many doing this are failing to achieve a clean burn, due to insufficient heat and fuel to activate the secondary burn system.

Running more than 100 cords of wood through a series of catalytic stoves, I've seen first-hand how difficult it can be to achieve cat light-off with a small load of wood, due to a combination of less heat coming off the load and less fuel being generated to support secondary burn. A non-cat should be even more problematic, in this regard, requiring roughly twice the temperature rise of a cat stove to achieve secondary burn.

If run WOT, I suppose one could still burn clean enough, either by more complete combustion in the initial burn phase, or by eventually getting the secondaries to sufficient temperature for reburn. But how many are running WOT for an entire burn, on these smaller loads?

Is it likely that small loads in a big stove results in not only much lower efficiency, but much dirtier burns?
 
I often run partial loads when coming home from work to combat the evening chill. 3-4 splits easily last the evening (in our weather).
When I start the stove, I run WOT until I have cat lightoff, although I mostly judge that by the exhaust temperatures as the BK cat thermometer is rather slow, as we all know. Then I turn the thermostat down. The cat thermometer stays in the active zone all evening, although not very much above the line.
So far no issues. After cat lightoff I also don't see any visible smoke coming from the stack, so I think the burn is pretty clean.
 
I see the advice of running small loads in a big stove come up often enough on this forum, either in milder weather, or because the stove is just too big for the house. But I wonder how many doing this are failing to achieve a clean burn, due to insufficient heat and fuel to activate the secondary burn system.

Running more than 100 cords of wood through a series of catalytic stoves, I've seen first-hand how difficult it can be to achieve cat light-off with a small load of wood, due to a combination of less heat coming off the load and less fuel being generated to support secondary burn. A non-cat should be even more problematic, in this regard, requiring roughly twice the temperature rise of a cat stove to achieve secondary burn.

If run WOT, I suppose one could still burn clean enough, either by more complete combustion in the initial burn phase, or by eventually getting the secondaries to sufficient temperature for reburn. But how many are running WOT for an entire burn, on these smaller loads?

Is it likely that small loads in a big stove results in not only much lower efficiency, but much dirtier burns?
I oftentimes run a smaller load in my Blaze King Parlor , early season, always had good success, maybe wood quality has some bearing on this, cat kicks in , last night 8 splits ash burned all night and left the house at 74 despite wind chills of 18 degrees. All scenarios differ.
 
Smaller splits Stacked with lots of empty space and a bit of extra kindling lit top down I think a clean burn is possible. That said I haven’t done it in a 3+ cu ft stove. And I use pine and poplar.

There are more variables that must be optimized to get it right so it is more difficult.

But really with the heatpump subsides coming online this will be needed less by many many people
 
Lots of people I know with non cats just throw a couple sticks in at a time once they establish a good coal bed. I think the stove is probably already hot and it doesn’t take much to achieve a secondary burn. A cold start may be a different story though.

Half loads are no problem for me but I have more of a medium sized stove (2.4 cuft firebox) than large. Sometimes I prefer running half loads a little hotter in really cold weather to keep the stove hot and not cause a large buildup of coals.

I find it more problematic doing this or small loads in a large cat stove
but not so bad in a small cat stove.
 
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I can eas
I see the advice of running small loads in a big stove come up often enough on this forum, either in milder weather, or because the stove is just too big for the house. But I wonder how many doing this are failing to achieve a clean burn, due to insufficient heat and fuel to activate the secondary burn system.
With good dry wood, I am seeing secondary combustion in 15 minutes burning 5 medium-sized splits. That's about 1/3 full. Our Castine had about half the capacity and with 4 splits it had similar warmup times. Dry doug fir takes off pretty quickly. I would think that this is not any dirtier than the open bypass startup while waiting for a cat to heat up.
 
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It's very possible, and also probable that most are not getting a clean burn. Can it be done? Yes, most certainly. Is it easy? No, I think it takes some experience in reading a fire to pull a clean fire on a very smallload off. If you can keep the top of the firebox hot, its much easier to do this. Lifting the fire up on a deep bed of ashes or a couple spare firebricks makes this easier.
 
I'm glad to see this question asked because I have just started burning in my new Drolet 1800. My first 2 burns I loaded up and WOW , had to open a door and window. I'm not needing a huge amount of heat just yet so I tried a lesser load (4-5 smaller splits) and that worked better for me at this particular time.

Question - while burning smaller loads should I let the fire do its thing until minimal coals before reloading or keep feeding to keep the roof hot and secondaries active.

Also, I have noticed that my door glass is already starting to get lightly smoky at the bottom. Is this normal from start up or cooling down at the end of burning ........or, what am I doing wrong ?

My wood is super dry (less than 10%)
edit: non-cat
 
Small loads aren’t getting the firebox hot enough to burn the glass clean.

If you don’t need more heat as the fire burns down, let it go out.
 
Coming from an Osburn 1600 (1.8cuft) to a stove twice it’s size with the 32NC (3.5cuft), it definitely is harder to make a small fire and have it burn right. You really need to use small (2”-3”) splits for it the burn hot enough to light off the secondaries.

When I use normal size splits it won’t get hot enough to light off secondaries, but then again I am still trying to figure this stove out as I’ve only run it a month and a half and not during the shoulder season.

Half load and above it runs great though.
 
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Thanks for the replies.
I'm also trying to learn my new stove and have to get comfortable with it burning way hotter than my previous 35 yr old PE.
 
So from what I’ve been learning/relearning/remembering about my 32nc is that cold starts can be a pain, but once it’s warm with some coals, it runs very easily even with a small load. And I’m sure most every stove is like that though.
 
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Coming from an Osburn 1600 (1.8cuft) to a stove twice it’s size with the 32NC (3.5cuft), it definitely is harder to make a small fire and have it burn right. You really need to use small (2”-3”) splits for it the burn hot enough to light off the secondaries.

When I use normal size splits it won’t get hot enough to light off secondaries, but then again I am still trying to figure this stove out as I’ve only run it a month and a half and not during the shoulder season.

Half load and above it runs great though.
It'll come with time and practice. I typically drop down to 3-4" splits for a quicker short burn. A softer wood will make it easier. I could not do a quick cold start with a dense wood like locust, hickory, or white oak but with soft maple or doug fir it's pretty easy.
 
It'll come with time and practice. I typically drop down to 3-4" splits for a quicker short burn. A softer wood will make it easier. I could not do a quick cold start with a dense wood like locust, hickory, or white oak but with soft maple or doug fir it's pretty easy.

Unfortunately 90% of what I have is red/white oak, so quick cold start’s don’t really happen for me LOL.
 
I think the key is if starting a stove from cold is getting a coal bed established initially with a sacrificial burn of a few splits then the stove will be hot enough where you can burn clean with only a couple splits added at a time. Or if just a short burn is desired to take the chill off I can’t see why anyone couldn’t get secondaries going off a cold start on a smaller load given the proper wood and conditions.
 
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Unfortunately 90% of what I have is red/white oak, so quick cold start’s don’t really happen for me LOL.
That was me, for about 6-7 years. Now it's hickory this year, and several years of ash will follow that.

2012 - Hurricane Sandy wiped out the oaks. We were flat-out buried in downed oak trees.
2019 - A local tornado went thru a large plot of hickory that my church owns, I was "cleanup boy"
2020 - Our ash trees started dying in huge numbers. We've been seeing it since before 2015, but the larger trees of interest took many years to succumb, and the numbers really spiked starting around 2020.

Burning oak all those years got me in the habit of seasoning everything 3-4 summers. That's the only way to get reliable "no kindling" starts on oak, and also not have it go into cat stall on low burn rates.
 
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VC Encore - downdraft cat stove: If I'm doing a cold start, I need a pretty full firebox in order to get the stove heated up enough to light off the cat in a reasonable amount of time. However, once the stove is warm I can reload 1-2 splits and the cat will re-activate no problem.
 
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It's very possible, and also probable that most are not getting a clean burn. Can it be done? Yes, most certainly. Is it easy? No, I think it takes some experience in reading a fire to pull a clean fire on a very smallload off.
Of all the responses, this is the one that follows my own experience and expectations, although begreen also brought up several good points around this.

Of course people can burn small loads cleanly, I had never questioned that in the OP. But I suspect that most do not, for the reasons already mentioned. We should put some care and parameters around our advice to burn small loads in big stoves, as this advice is often being given to newbies who are just shopping for their first stove, or having just purchased one and coming here to complain it's overpowered.
 
That was me, for about 6-7 years. Now it's hickory this year, and several years of ash will follow that.

2012 - Hurricane Sandy wiped out the oaks. We were flat-out buried in downed oak trees.
2019 - A local tornado went thru a large plot of hickory that my church owns, I was "cleanup boy"
2020 - Our ash trees started dying in huge numbers. We've been seeing it since before 2015, but the larger trees of interest took many years to succumb, and the numbers really spiked starting around 2020.

Burning oak all those years got me in the habit of seasoning everything 3-4 summers. That's the only way to get reliable "no kindling" starts on oak, and also not have it go into cat stall on low burn rates.

A lot of oaks where I live are getting diseased and dying off so I’m absolutely loaded with it.
 
Unfortunately 90% of what I have is red/white oak, so quick cold start’s don’t really happen for me LOL.
That's understandable. You have to play the cards that were dealt. Scrounge around and gather some softwood and keep a stash around for the shoulder season. Birch, ash, alder, soft maple, etc. are also good for this.
 
That's understandable. You have to play the cards that were dealt. Scrounge around and gather some softwood and keep a stash around for the shoulder season. Birch, ash, alder, soft maple, etc. are also good for this.

Thankfully, I just took out a big white pine on my property so I have about a cord of that seasoning for next years shoulder season.