Design Deficiency - 'Too Many Coals'?

I'm kind of a "lazy" burner in some ways. I'm most always at home, and once I get the space up to temp, I like to maintain it there. Consequently, I have a tendency to be the kind of burner who tosses a split or two in now and then throughout the day, rather than the "purist" who jams the firebox full and waits for the cycle to complete before reloading. Sometimes I get a big bed of coals built up. When that happens, I open the primary and sometimes crack the loading door (if I'm gonna be there with it) and enjoy the heat produced as the coal bed burns down. In any case, I either load it up for the night or I bank the coals before retiring, depending on whether it's the house stove or the shop stove (still haven't had to spend the night in the shop). In the morning I usually have a few coals in the Liberty, and I usually have to re-start the shop stove from nearly cold...but there's little left in either box than ash and possibly a few coals, depending on how late I stayed up and how tightly I packed it before bedtime. This is with nothing but softwood, mind you. Gotta love Super Cedars! Rick

I try to let my coals burn down as much as possible, but with the cold weather I can only let them burn down so much before the house starts cooling down.
The coals are usually pretty small when I take them out. As far as wasting BTUs, who cares when the wood is free.
If I was fortunate enough to have a draft control below my coal bed, I might be able to do a better job of burning the coals down to ash, but I don't...shucks.

IMHO, part of the problem may also be not getting enough heat out of the stove. I used the example in cowboyandy's thread...if the stove is designed to burn 100,000 btu worth of wood and get 75,000 btu out - but for some reason you can only get 25,000 btu out (blowers aren't working, lack of airflow, etc) Then you're forced to try and burn 300,000 btu worth of wood to get the same heat. The firebox just gets packed up with coals.

So always make sure you're getting the max efficiency/heat out of the stove which will reduce the amount of wood you need to burn and may eliminate some coal build-up issue.

I'll be experimenting with this over the weekend. We tend to load the stove up for long burns over night or during the day, but add a few splits every few hours while up and about to maintain the heat. With these really cold nights, I've seen what others have said about the Napoleons - that they tend to run a bit hot. It seems like I'll throw in some wood, leave the primary open wide to let it get going, and before I know it it's at or above 700*. As a result, I tend to shut it down about half way when it hits 500 or 525, then let it cruise up to 600 and shut it down the rest of the way. The coal beds get a bit too thick, which makes it that much harder to put enough fuel in for the long cold nights, so it's not heating as well as it could. I'm going to try keeping the air cracked this weekend and see how she behaves.

I have also experienced the coal buildup issue, and I believe that this is another problem related to the way non catalytics are designed in conjunction with too much draft in cold climates. In the situation I have described in a few threads, I basically have to burn my T5 with the primary closed 98% to avoid over firing the stove. In this situation, the vast majority of the air reaching the fire is secondary air with very little flowing through the primary (I also had to modify the primary control so that it can be fully closed). Given this situation, air reaching the top of the coals will create a layer of ash on top of the coals, which blankets them in a fairly short time. This then reduces the heat output dramatically. To get more heat output, you have to open the door, stir the coals (ash settles to the bottom) and open the primary some, but even the primary air flies over the top of the coals.

Looking at any coal stove, the only way that coals can be effectively burnt is to provide air under the coals. The EPA test disdains user controls that are in any way complex, so not surprisingly, there are no draft systems provided for getting air below the coal bed. My T5 unintentionally has such a draft control, except it is called an ash chute and not intended for the purpose. PE kindly bolted the ash chute into place, so that means that I can build a draft control of my own (I don't use the ash chute anyway) and swap it out for the ash chute. I burn down coals about once a day using the ash chute, but it is certainly hard to control, since it was never intended to meter a controlled amount of air. By getting air under the coals, I can get a hot burn, with flue temperatures (measured with a probe) of 500F and plenty of heat from the stove. As the coals burn down, I need to keep raking them into a cone over the air intake, but that doesn't take much time at all.

I think I will end up running air into a series of pipes (similar to what one has for secondary air) in the bottom of the stove. There is a foamed inconel out there, but don't know if I could afford it. It would distribute the air over the whole coal bed and last forever.

My stove had a small 3/8ths inch hole to feed unregulated air to the doghouse. I drilled it out to 5/8ths to help burn down the coals faster but it had the unfortunate side effect that a stoked up overnight load would burn too fast and leave no coals in the morning. I ended up drilling it out to 7/8ths and fashioned a regulating valve out of 3/4" copper fittings. Now I open it when I need to burn down the coals and close it for overnight burns. I notched the control so that it cannot be closed off completely.

I agree that loading style has a lot to do with coaling. Wood species is a large factor as well. What isn't mentioned very often though, is that moisture content is also a factor. Wood that is not well seasoned will coal more than good dry wood.

The bottom line is that a wood burning stove that does not have a grate system is a batch or cylclic burning heater. If you want to burn at a constant high output you need a grate system to burn off the coals and get the ashes out while you keep putting wood in on top.

I don't think that's the "bottom line", actually. I get perfectly good performance out of both my woodstoves without grates, and I never find it necessary to remove coals. Depends on how you burn it, more than anything else, I think. Rick

This coaling issue, tells me you need to burn pine. Ive ran a EPA non CAT and now an EPA CAT. I have never experienced these problem's. Is it all hardwood you guys burn? You might as well burn softwoods if your throwing out your hardwood that has not completely burnt. It doesn't make sense to me. Is any one still getting coaling with softwoods like pine or spruce?
OK now take it easy on me. :lol:

I think that quite often, heavy coaling is caused by bark. Some woods are worse than others. Honey Locust is the one that does it to me.

The coals don't always go to waste.

We had some freezing rain. My driveway is on a slope and you could barely walk up it. I had a stove full of coals and had an idea. I filled my ash bucket full, walked out front and slung them down the driveway. No more ice on my driveway, but there sure was a slick spot on the road.

Woodford said:

I think that quite often, heavy coaling is caused by bark. Some woods are worse than others. Honey Locust is the one that does it to me.

Click to expand...

Nope. Good thought, but no. I get lots of coaling even with a box stuffed with small splits of totally barkless very dry rock maple and primary half open for maximum heat.

Clearly, my issue is that my stove is too small for the job, so I can't in really cold weather (-20 last night, -12 tonight) let it do its normal burn cycle without drastically cooling off the house and have to keep throwing wood on it while it's still at temperature with a box full of orange glowing coals. If I let it go below that, the temperature drops fast and it takes forever to get it back up to comfortable again. Not the stove's fault, I'm asking it to do more than it's capable of.

I can get both my stoves full of coals burning white spruce. Englander 30 and Blaze king King Cat. Happens more often with my Englander but that's because I'm warming up the cabin and trying to keep max heat output for 6-8 hours. Same thing happens with the Blaze king if i keep piling more wood in the firebox as soon as there's room for it.

It is far less noticeable with the Blaze king due to its firebox depth.

The lack of firebox depth on the Englander is my only complaint about the stove.

north of 60 said:

This coaling issue, tells me you need to burn pine. Ive ran a EPA non CAT and now an EPA CAT. I have never experienced these problem's. Is it all hardwood you guys burn? You might as well burn softwoods if your throwing out your hardwood that has not completely burnt. It doesn't make sense to me. Is any one still getting coaling with softwoods like pine or spruce?
OK now take it easy on me. :lol:

Click to expand...

The number one cause of coal build up in my setup has been green wood, hands down. On a side note, I heard so many positive reviews of 'packing the stove' that I've recently been trying bigger fills in my stove, getting it going and then shutting her down. I'm roasting, got the windows open. The difference is jaw dropping, I am amazed that it can put out so much heat with the vents closed so far. Also, no coals. By the time the temperature drops from 80 to below 70, about 5 hours at current temps, there are no coals to be found, and very little ash. And that's mixing greens and seasoned.



TS

I make coals burning my blaze king. I like em. On sunday when I am home all day I burn the coals. I get almost a full day of good heat off them. Twords the end of the day I scoop out ask and reload. The coal burn once a week is hot and clean It leaves the inside of the stove and the cat looking nice.

When I get too big of a coal bed, the bestest and fastest way for me is to open the door wide and give it full air. I leave the blower on and the air coming over the top of the stove pushes all that intense heat coming up out of the box. It's like burning on high!
I only do this with the flue bypass open.

We had the coal problem when we first got the Fireview but rarely have it now. It is a matter of simply learning how to operate your stove.

Methinks that most people, judging from the posts on this forum, want their wood stoves to perform much like their furnace. That is, they don't mind adding the wood and setting the controls, but then they want everything automatic. Wood stoves are not like that at all. They need some tender loving care and some input from the operator. I don't know of very many stoves where you can set a control and leave it there until you reload the stove and just keep on doing this.

On our stove, when the wood gets burned to the point that it is all red we open the draft about 1/2 way. After a while the pile has collapsed and is not level, but more level that when we opened the draft. At this point we open the draft full. We also push some of the coals towards the front but at this point we can't do too much. After an hour we can usually make a big pile towards the front. Usually when the stove has dropped to 350 degrees or maybe 300 degrees the coals have burned down a lot so we have good room in the firebox. Then we put in what is required for heat that day. We do not fill our firebox with every load. We do that only at night or if we are to be gone a good part of the day.

In my PE Summit insert, I get the most coals when I go for the long burn time. Overnight and while we are at work. After these long burn cycles I rake things around to sift out the powdery ash, then pull the coal to the front where the air intake is. I then put a couple small peices on top of the coal pile and burn the stove with the air intake 2/3 open. This brings the Rutland gauge stuck to the face of the stove back up into the 4-500 range and burns down the coal pile rather quickly.

The BEST way I've found to run the stove for heat AND minimal coals is stacking some short peices in the front on the coal pile and running the stove on 1/4-1/3 air. Like KeithO mentioned, I CANT pack the stove full and give it much air or it will be way too hot. This 1/3 to 1/2 full load and a decent amount of air gives me the best balance of heat and low coal build-up. This requires tending every 2-3 hours, so we only can do it over the weekend.

An automatic draft control would be nifty for the full fuel loads. Open to 1/4 after 3-4 hours, 1/2 around 5 hours....

This is a great post. I load mine only at night and in the morning before work. When I get home I try and burn small splits or soft woods to get the house up to temp.This in turn will heat the box up quickly and the wood will burn faster and I dont get that much coal .Since I'm pretty new to burning I find my self splitting wood to smaller sizes with my Fiskar ax. One hour before bed I open up primary to try and burn down the coals and depending on temps Ill load It up and start the day all over again. I really like coals as coal's are a burner's best friend. :lol:
All you need is a good sharp Fiskar ax hot burns in the evening and good time management and you wont have this problem. Haven't cleaned out any ash in two weeks.
Maybe Im burning wrong but if I am I like it :coolgrin: