unburned coal (left overs) in coal stove MARK III

spaserg · By: **spaserg** On: Thu Feb 14, 2008 2:35 pm

Hi, I have MARK III stove dual fuel wood and coal. When I burn wood it's perfect, with coal have problem : Coal do not burn to complete ashes, it's always small parts inside ashes not burn completely when stove finished to burn .Usually I reuse them trying to lover cost of heating., but it's pain in a** to clean stove and dig out unburned coal .I use stove size coal sometimes nut size. It's looks like nut size burn better, fewer leftover, but maybe smaller size not so visible. Anyone has the same problem? apreciate you answer.Serge.

LsFarm · By: **LsFarm** On: Thu Feb 14, 2008 9:24 pm

If you burn just coal, all the time, and just add more coal onto the top of the fire, and shake the ashes out from under the fire, the coal will burn completely, if it is able to be burned.
The ash from a large piece of coal will be larger and chunkier than from small pieces of coal,, And the large pieces take longer to burn fully, so they need to stay in the stove longer to burn completely.

It sounds like you let your stove's coal fire burn out,, I would think you will have better luck with fully burning your coal if you never let it go out except for maybe once a month cleaning.. Good coal will burn to just powder or flaky ash...

Hope this helps... Greg L

Wood'nCoal · By: **Wood'nCoal** On: Thu Feb 14, 2008 10:05 pm

That's correct, you need to fill the stove fully, to the top of the firebrick, and shake the fire before adding fresh coal. Try using nut size, stove size really doesn't burn that well in a Harmon.
Unburnt coal is usually an indication of poor quality, good deep-mined coal will burn almost completely.

coal berner · By: **coal berner** On: Fri Feb 15, 2008 12:27 am

Wood'nCoal wrote:That's correct, you need to fill the stove fully, to the top of the firebrick, and shake the fire before adding fresh coal. Try using nut size, stove size really doesn't burn that well in a Harmon.
Unburnt coal is usually an indication of poor quality, good deep-mined coal will burn almost completely.

What do you mean Almost Completely It should always be Completely Burned if you have you stove & Draft Setup right :lol:

coalstoves · By: **coalstoves** On: Fri Feb 15, 2008 3:16 am

Wood'nCoal wrote:good deep-mined coal will burn ( almost ) completely.

Ever figure what ya paid a Ton all inclusive +

Wood'nCoal · By: **Wood'nCoal** On: Fri Feb 15, 2008 8:09 am

coal berner wrote:
Wood'nCoal wrote:That's correct, you need to fill the stove fully, to the top of the firebrick, and shake the fire before adding fresh coal. Try using nut size, stove size really doesn't burn that well in a Harmon.
Unburnt coal is usually an indication of poor quality, good deep-mined coal will burn almost completely.
What do you mean Almost Completely It should always be Completely Burned if you have you stove & Draft Setup right

Based on my results as seen in the ash pan, it is changed to completely. Don't know what I was thinking when I wrote that "almost".

spaserg · By: **spaserg** On: Fri Feb 15, 2008 2:36 pm

Thanks to everyone ! Yes ,fire goes out. True. It's not hold fire whole night.Usually, I put load at 11PM and wake up at 6.30 AM. stove rarely have some fire. When I use nut size not stove size it's look like this size more sutiable for Mark stove, sometimes it's burn almost completely,Stove size coal leave big chank of melted brown color things(looks like melted metal or stone).My toughts may be something wrong with air consumption (maybe need damper to cut air ? or fan to bust more air to stove???) or I took too much heat by fan at back of stove. But when I use just wood all seems fine. I'm just pazzled.Was thinking coal will be better than wood. I have been told Harman best in industry stove for coal. Is it true or some stove better? Thanks.Serge.

LsFarm · By: **LsFarm** On: Fri Feb 15, 2008 3:59 pm

Hello Serg, you are burning your stove way too hot and fast... The red melted 'thing' is a clinker, it is melted ash in the coal.. you have to have a VERY hot fire to create clinkers in you Mark III

I would say that 99.9% of Mark III stove opperators are getting at least 12 hours of burn out of a load..

So: lets look at this,
first, load the stove FULL, all the way to the top of the firebrick.. and mound the coal up in the center..
Next, get a thermometer for the stove and stack... you want around 350-400* or so on the stove body just above the door. and not above 300-ish on the outside of the flue pipe.

You should only have the spinner knob on the ash pan door open maybe 1 or 1-1/2 turn.. This is a difficult 'educated guess' on my part, I don't know at all how much chimney you have, how strong the draft is, or the quality of the coal you are burning, or if you have a barometric damper installed [this is recommended by the stove manufacturer]. You should have the spinner knobs on the loading door closed. The only air getting to the fire should be through the ashpan door spinner.

You should be able to get a moderate amount of heat for in excess of 12 hours with a full firebox... If you are not, then you are trying to burn your stove way too hot... if you need this much heat , then you need a bigger stove, ! Like maybe a Harman SF250...

But there are lots of people with MarkIII stoves on the forum,, I'll let them post with the size of their house, quality of windows and insulation and their burning experiences...

Greg L

titleist1 · By: **titleist1** On: Fri Feb 15, 2008 4:14 pm

Serge, can you get a picture of your ash? Some on here are pretty good at diagnosing this stuff. It could be a number of contributing factors, the first I would check is the quality of the coal. Maybe get a bag or two of some other brands to see if you fare any better. The second would be if any ash is laying on top of the baffle or in the back of the stove (is yours a rear exhaust or top exhaust), or on any elbows on its way out the flue. With mine, I can tell if its time to clean the flue pipe by how it burns. About once a burn season I will take apart the flue pipe and vacuum out the fly ash laying in the elbow and horizontal run through the thimble. Other factor may be the draft on your chimney set up. A picture of that might help.

I can bank mine at night around 9-10pm and will still have a strong fire the next day. Not a weakling, "nurse it back to life with wood" fire, but a strong fire 12 hours later. I follow pretty much the same practice as I have read in the harmon shaker thread, open ash door to boost fire, add a thin layer of coal & get that cracking, shake down vigorously, add more coal, shut ash pan door after a couple more minutes of the "kick start". Takes maybe 10 minutes total time. This is my 15th year with a Mark III, it took a little (ok a LOT of) practice the first year to get it right. Plus there was no 'net with a great forum like this to shorten the learning curve back in the olden days. I have burned a lot of wood in mine over the years just because I have it, but I prefer burning coal in it.

I am heating a 2000+ sqft ranch house with it in the basement. If I didn't get lazy, too busy at times, sick or a spasm'ing back - our furnace would never need to kick on. Flue pipe temp with a mag thermometer is around 225 about 18" above stove. Ash pan spinner open from 1 - 2 & 1/2 turns depending on outdoor temp, coal, how full is ash pan, etc, etc.

spaserg · By: **spaserg** On: Tue Feb 19, 2008 1:49 pm

HI! Thanks ,guys!!!! I finally get the 14 hour fire with one load coal. My mistake was pointed by GREG L "too hot and too fast".That's correct.When I turned knob on ash door just 2 turn open Mark III shows his ability to burn longer. I really apreciate all of you guys, whole winter I was burning coal wrong way, I was thinking coal NEED MORE air flow to burn than wood (with wood ash door knob closed completely to burn whole night). Now coal burns to total ash . I use stove size coal now , but when I burn nut size I think it's better,TITLEIST1 right .
My set ut very simple: heating 2000+ ranch .Stove in bacement. 6" flue Simpson- chimney outside of house. It has back fan on stove and I bought Magic Heat ($70 at ebay) for pipe that give me a lot of hot air.If it cola outside I can turn on fan and point it on stove to take some heat from sides (radiant heat). To get hot air upstairs I use central HVAC fan put on circulation.Plus hot air come up by itself and floor is warm(I love it). Next year planing to put stove closer to HVAC system to get hot air not all over all bacement ,but directly in to heating ducks .
Again: THANK YOU !!!!!!! FINALLY!!!

rberq · By: **rberq** On: Tue Feb 19, 2008 8:12 pm

One thing more, install a barometric damper if you haven't already, and use a manometer to set the baro (or not -- I just experimented with baro settings until it "felt right").

You may not need the MagicHeat once you control draft properly -- be careful it doesn't cool the flue gases so much that draft is inadequate.

spaserg · By: **spaserg** On: Wed Feb 20, 2008 1:37 pm

Hi! I use MAGIC HEAT to take as much heat from system as possible.After MH reclaimer I have mag thermomter to control (to see) temp of flue gases.I try to keep temp as indicated on termometer safe zone (i belive someting from250 to450) It's white zone indicated to prvent creozote build up inside chimney.
Another Q? : Creozote can build up only from wood burning or coal has something to build also? Thanks.Serge

dutch · By: **dutch** On: Wed Feb 20, 2008 3:29 pm

If I understand your post, you have the magnetic thermometer above your
MH Reclaimer?
you are still getting temps up above 250?
that sounds high to me,
with my Mark III, it seems to put out the most heat
with my stack temp around 200. I am learning to try and
not open the stove up so much to get towards 300 if i can help it,
and I think i get more heat from the stove this way.

others can also respond, but I don't like to see
that temp anywhere near 400!

but it sounds like you are gradually getting the hang of
the coal stove, i'm still learning after 3 years!

LsFarm · By: **LsFarm** On: Wed Feb 20, 2008 4:32 pm

Hello serg.. to answer a few of your questions:
NO..coal does NOT leave anything in the chimney but dust..[called flyash] So you do NOT have to keep the temperature in the chimney hot as you are,, in fact this is a waste of heat and coal..

Most people with the hand feed stove like you have try to keep a fire going all year long.. they start the fire in the begining of the heating season, say early November and keep the same fire going all season long, they never let the fire go out..

This is done by filling the firebox up FULL, up to the top of the firebrick in the firebox, then controling the amount of air to get a hot fire, but not overly hot so that you have too much heat going up the chimney... Heat going up the chimney is just wasted coal.

A heat reclaimer in the chimney pipe is used to try to get the last little bit of heat out of the stove before it leaves and goes up the chimney.. your thermometer should hardly even show a warm pipe AFTER the heat reclaimer. With your ashpan door air knob open 1 turn or 1-1/2 turns, you should be able to get plenty of heat out of the stove,and just add more coal every 12 hours, and shake the ashes down, empty the ash pan, then top off the fresh coal... and go another 12 hours.. on and on, and only make a fresh new fire if you intentionally let the fire go out.

Hope this helps.. Greg L

bugize · By: **bugize** On: Thu Feb 21, 2008 8:46 am

,
i have a mark3 in my basement that i heat a 24x40 ranch with a entry way. an outside chimney with a ss liner.the temp this morning outside was 2 above,i set the draft knob last night at 1 1/4 turn open,maybe a hair more,the stack temp was about 230(12"above elbow exiting the stove),the house is 72,13 hrs later.
i have found that anything above 300 degrees seems to go up the flue,i do have a baro with the weight backed all the way out(i dont get a strong draft),mostly works when the wind is blowing.
if the overnight temps are to get below zero,i usually only back the knob out no more than 1 3/4 turns,i work a swing shift and times cant tend the stove for 15 hrs.when i get home my house is the same temp it was when i left.i have had my stove going steady since the monday following thanksgiving. i hope this helps give you some idea on different things to try. :shock:

unburned coal (left overs) in coal stove MARK III

unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III

Re: unburned coal (left overs) in coal stove MARK III