Coal Bed, Too much of a good thing?

I recall another member talking about using nice small dry pine splits to burn down coals, and it was the best advice I ever got! Well, actually I get great advice from the experts here all the time, but anyway, the pine splits worked magnificently at burning down the coals last year, so much so that I purchased a cord of pine last spring so that I am always prepared. Besides being great for burning down coals, I find that burning a blazing load of pine when I get home from work really warms the house up fast, and it doesn't leave a coaling problem at all..... I save the good hard wood for my overnight fires....

Just keep in mind burning down the coals with small dry splits of pine does work, but it may be a bandaid for coals caused by unseasoned wood. Get your wood dry and there will be less of a coaling problem and you will get more heat from your wood.

Also, the coals need exposure to air to burn. The more exposed surface area, the better. When you have that many coals, I find that making mounds with channels to allow plenty of air flow works best. And once you're coaling, open the air fully.

Keep in mind, even though you insulated the fireplace you have an insert and an exterior chimney. It seems common for that setup to not provide quite as much heat as a free-standing stove with interior chimney. Given the description of the house, large and drafty with high ceilings and lots of glass, I'm not totally surprised that as you get down to coals the house is cooling a good bit. But that's going to be a bigger problem for you in the dead of winter, when it gets REALLY cold and windy.

Did you ever put the block off plate in? Having just the rock wool will still allow air flow, and without dead air in the chimney you are going to have more heat loss than with an airtight seal. I am assuming the installer sealed the top plate, so you have a tight seal up top, but that would be worth confirming. Also, are you using a blower? That will be a factor, as well.

Highbeam said:

The osburn 2400 insert is marketed as 3.2 cubic feet which is a good sized stove. Smaller than my NC30 and being an insert is at a disadvantage.

I propose you are asking more of the stove than it can provide.

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How does the wood know the room is too large?

Firefly1 said:

I have been using my new Osburn 2400 insert (just installed last week) for the past few days and I am constantly experiencing having too many coals left behind after burning. Just to give you an idea of my process I am burning oak wood seasoned about a year, year and half. During my first burn I loaded the Osburn up and let it burn. I followed the steps of choking in the air intake in steps until it was pushed in all the way. I have a good draft and have experienced secondary burning without any issue. At some point the heat emitted by the insert goes down and am left with a bed of coals at which point I load in more wood. Repeat this cycle a few times and I now have so many coals in the insert which has significantly decreased the amount of wood I can burn in the insert. Besides having too many coals, the problem I am experiencing is the wood burns down leaving coals which do not emit enough heat to keep the house warm. I proceed to load more wood and the same happens again. What am I doing wrong? Just a little about the the space I'm heating the home is about 2500 square feet, open concept with high ceilings and lots of glass (a lot of floor to ceiling glass walls). I have attempted to burn off the excess coals by raking them forward and opening up then air intake but this hasn't been too effective. Please advise, thank you.

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mass_burner said:

How does the wood know the room is too large?

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The wood doesn't know anything. The operator is trying to run the stove too hard which causes coal build up.

The stove doesn't really know the room is too large (it's stove brain is kinda small that way ). But what happens is folks load their brainless stoves before the previous burn cycle is completed, to try to compensate for a stove that is too small.

This results in the coals not getting burned down proper-like.

Well it finally got cold enough to burn around the clock for a week now and I had excessive coals after day two. It had to be 3 to 4 inches thick as it was flush with the door ledge on the 2400i. I raked all the coals forward and left the door cracked and then raked again, after about 15 minutes of this routine most all the coals were burned up and there just a small pile of ash and coals left on the firebricks on the floor of the stove for a reload. This worked well I was worried I was going to have to shovel and relight the stove. It seamed most of the coals formed in the back of stove and especially after overnight burns. Now during reloads I rake all coals to the front left side of stove and leave the door cracked for about a minute, coals get forge hot and start up the wood as soon as it is loaded. In addition the coals burn up and after a week of continuous burning the coal ash situation is more than acceptable in the stove.

On a side note, during an overnight burn of 10 hours or so I've found I can rake the coals forward, leave the door cracked and get a fire going with no paper or kindling, just small splits. A benefit I suppose of these slow burning coals in the back of the stove.

Still learning the stove but the Osburn 2400 is a beast. Looking forward to learning it all over again next winter with well seasoned fuel.