Question about Green Mountain 40 method + burning oak?

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ThereAreGoats

New Member
Mar 31, 2022
8
Brooklyn
Hi all,

I need to order more firewood for my Green Mountain 40. I've been using ash, but I'm only getting burn times of about 3-4 hours (the last one or two hours is just coals). That's with it stopped down as much as I can without tons of smoldering. I want longer burn times, but given that I sometimes have trouble keeping the ash blazing, should I stay away from oak?

Here's my general method. I use the top-down approach, starting w/ a few small splits (4-inches) of seasoned Ash on bottom and newspaper knots/tinder/kindling on top. Air fully open and cat bypass on. Lighting it usually goes pretty well, and I only have to keep the door cracked for a few minutes before I can close it and let it go. But there usually does come a point like half hour in where stuff starts smoldering and I need to give it another push by opening the door a little again. (You can only orient the wood east/west because firebox is so small). But beyond that, I rarely have to touch or stoke it at all before coals. Often I'll move the back piece of wood away from the back wall so it can burn, but that's it.

Once I have my coals, I let the stove get down to about 300 (measured by magnet thermometer on top) to stretch the heat. Then I rake coals forward and to the sides as much as possible so I don't smother them, then put like four bigger splits in, trying to make the lip of the front split make contact w/ coals. It often takes several minutes for them to ignite again, which seems weird. Lots of smoke in the meantime, and often lots of smoldering. Air fully open, cat still engaged.

Given all that, is this just a bad stove for super hard wood? Would I have an even tougher time getting oak to light/stay lit?

There's the additional problem of temperature. On a few occasions, when I've thrown in full splits on coals, the stove has gotten past 700 and the cat temp has neared overheating. I'm assuming the wood I had in that day was Ash but maybe not. In any case, it's never actually gone into the red. But is this another reason I should avoid oak? And what do y'all think of my general method?

Thanks a bunch!

Robert
 

begreen

Mooderator
Staff member
Nov 18, 2005
93,141
South Puget Sound, WA
Oak is great firewood, so are hickory and locust. The difference however is that these hardwoods will need at least 2 yrs to season completely unless the process is accelerated. That means this wood bought now will be for the '23-'24 season at the earliest. Ash dries in a year so that is better if buying for the '22-'23 season.

You can help accelerate drying by orienting the racks facing south with good sun exposure and so that the prevaling winds can blow through them. The stacks should be top-covered. Even better would be to make a solar kiln for the wood. These topics are covered in the woodshed forum.
 

icestationzebra

New Member
Mar 29, 2022
7
NY Southern Tier
Yes, oak in particular really takes alot of time to be optimized in my experience... when I get a load of "seasoned" mixed hardwoods in the Fall i'll almost always pull all the oak out and stack it in a dry garage bins until next season. Locust too.... I once got a couple of cords of "seasoned" honey locust that I ended up sitting on for 2 years before burning.
 

ThereAreGoats

New Member
Mar 31, 2022
8
Brooklyn
Yes, oak in particular really takes alot of time to be optimized in my experience... when I get a load of "seasoned" mixed hardwoods in the Fall i'll almost always pull all the oak out and stack it in a dry garage bins until next season. Locust too.... I once got a couple of cords of "seasoned" honey locust that I ended up sitting on for 2 years before burning.
The guy I'm considering buying from says he has seasoned oak to sell, but I'd still like to get out there with a moisture meter to measure it myself; I need this for this coming fall/winter. Have you found that you get decent amounts of oak in your batches of mixed hardwoods?
 

stoveliker

Minister of Fire
Nov 17, 2019
4,353
Long Island NY
From your description I'm not sure you're loading up the firebox to the gills? Any claimed long burn time is with the firebox as full as possible.


Can you post a pic of a load that will last 4 hrs?

(And yes, the smoldering, smoke, trouble starting the splits are indicative of wet wood.)
 
Last edited:

kborndale

Feeling the Heat
Oct 9, 2008
378
LI
The guy I'm considering buying from says he has seasoned oak to sell, but I'd still like to get out there with a moisture meter to measure it myself; I need this for this coming fall/winter. Have you found that you get decent amounts of oak in your batches of mixed hardwoods?

There is a 95% chance that the dealer does not have wood that is ready to burn. I would definitely buy wood now but it won't be ready to burn until next winter at the earliest.
 

stoveliker

Minister of Fire
Nov 17, 2019
4,353
Long Island NY
And it being ready next winter means you're lucky. I.e. it actually was drying already for a full summer.
 

Ashful

Minister of Fire
Mar 7, 2012
16,342
Philadelphia
I've been burning mostly red oak since early 2014, and it's really hellish firewood. Yes, it can pack a big punch on BTU's, if you can manage to get it dry. But getting it dry is quite a challenge, not to be done in less than 3 summers, based on my experience in eastern PA. Meanwhile, we can't even begin to count the number of firewood sellers who claim to have "seasoned" firewood, who fail to deliver on that, I think kborndale is being overwhelmingly optimistic in suggesting there's actually a 5% chance of you buying dry oak.

Ash is wonderful. Quick drying, and pretty good on the BTU score, nothing to complain about. But if you're only getting 3 - 4 hours from it, there are two obvious questions:

1. Is a load of ash every 3 - 4 hours what is actually required to heat your place? If so, trying to stretch the load longer will only leave you cold, as there's only so many BTU's per cubic foot of any wood.

2. If you're saying that a load every 3 - 4 hours is more heat than you need, and that the stove is just not controllable, that's another matter. The folks here can help you with that.

But which is it?
 

Rickb

Minister of Fire
Oct 24, 2012
1,195
St.Louis
I can run 3 - 4 small to medium ash splits and heat my small area for 5 - 7 hours, depending on how cold it is. I actually prefer it over oak. Oak is a little more heat over time but harder to get heat at first unless I load it after the stove is hot.

Im a bit concerned your only getting 3-4 hours on a load of wood. And we have had lots or posts with people having draft issues with green mountains.

Another words. Your not going to swap from ash to oak and go from 3-4 hours to 10 hours of heat... it doesnt work that way.
 

begreen

Mooderator
Staff member
Nov 18, 2005
93,141
South Puget Sound, WA
The guy I'm considering buying from says he has seasoned oak to sell, but I'd still like to get out there with a moisture meter to measure it myself; I need this for this coming fall/winter. Have you found that you get decent amounts of oak in your batches of mixed hardwoods?
The trouble is, the idea of "seasoned" varies from person to person. One can call wood "seasoned" after it has been split last month. Bring a moisture meter and an ax. Pick out a couple of the heaviest 4-6" splits, bang them together. Do the ring or go thunk? Are the splits greying and checked on the ends? If they fail those two tests, resplit them, then test on the freshly exposed face of the wood in the middle. My guess is that the mc will be north of 20%.
 

ThereAreGoats

New Member
Mar 31, 2022
8
Brooklyn
From your description I'm not sure you're loading up the firebox to the gills? Any claimed long burn time is with the firebox as full as possible.


Can you post a pic of a load that will last 4 hrs?

(And yes, the smoldering, smoke, trouble starting the splits are indicative of wet wood.)
I only have a shot of the initial fire setup, not what I'd put in it after I have coals. But definitely coulda put more in it here.

IMG_5459.jpeg
 

ThereAreGoats

New Member
Mar 31, 2022
8
Brooklyn
I've been burning mostly red oak since early 2014, and it's really hellish firewood. Yes, it can pack a big punch on BTU's, if you can manage to get it dry. But getting it dry is quite a challenge, not to be done in less than 3 summers, based on my experience in eastern PA. Meanwhile, we can't even begin to count the number of firewood sellers who claim to have "seasoned" firewood, who fail to deliver on that, I think kborndale is being overwhelmingly optimistic in suggesting there's actually a 5% chance of you buying dry oak.

Ash is wonderful. Quick drying, and pretty good on the BTU score, nothing to complain about. But if you're only getting 3 - 4 hours from it, there are two obvious questions:

1. Is a load of ash every 3 - 4 hours what is actually required to heat your place? If so, trying to stretch the load longer will only leave you cold, as there's only so many BTU's per cubic foot of any wood.

2. If you're saying that a load every 3 - 4 hours is more heat than you need, and that the stove is just not controllable, that's another matter. The folks here can help you with that.

But which is it?
A load every 3-4 hours is fine to heat my place (although my place is always already warm when I light the first fire; after I close the door, I turn my mini-splits off). Even on super cold days (below zero), it's great for my little 900 square-foot cabin. But I take your point about the oak. That's precisely my fear.