Mark II coal burning issues!

Well my dad just replaced his wood stove with a Mark II and burning pine to get the coal started you can hit 500-550 on the stack after getting the pea coal going you see around 300-400 on the stack for about 12 hrs then it drops to around 150 200 and never seems to recover. As for draft around 200 it's less then point .02 when it’s around 500-550 it's around .04 to .05. Chimney is 15ft to 18ft high and is 8x10 clay lined the stack pipe going into the chimney is 6". The seals on the door and clean out are good. At the moment we cracked a window in the garage to see if it's too tight, which is where the stove is and used. Now there is nothing within 10ft of the chimney except I can say that it doesn't go above the peak of the roof but it's over 10ft from the chimney. I attached some pictures take a look and let me know something to check because he's about to give up on coal.

Pea coal (kind of small for hand fired) may not be your best choice with that, have you tried nut? Does the coal burn to ash, or leave a crusty chunk?
Is the stove in the basement or on the first floor? If its first floor, you don't have a lot of chimney.
Does your chimney draft, if so how well?
Are you filling the firebox completly?

That looks like it should cook up a storm, somethings wrong. Once he figures it out, he will never burn wood again (well, maybe to start a coal fire).

As suggested try some nut. I'd imagine after 12 hours its time to put some more coal on though? That's the general schedule for most people. Shake and add coal in the morning, shake and add coal in the evening.

Note that there's many people that use pea in hand fired stoves, even large furnaces. Shouldn't be any different except you can control it better and can't get it ripping as fast like you can with nut. The pea restricts the air flow which may just be posing a problem for you.

Is it possible to burn out all the coal in a MK II in 12 hours?

My guess is yes. How many turns on the air inlet?

I get a 24 hour burn with 1/2 turn from closed.

3/4 of a turn easily gets me a 12 hour burn.

We might need more info.

Are you burning bagged coal? There is a lot of inferior coal floating around out there. Bagged coal, to the best of my knowledge, is all from strip mines. The quality and purity can very from "good" the almost "un-burnable".
Before you give up try to find a few bags of Blaschak coal. It's strip mined but relatively pure. I think you will find it's the coal that you have that is causing the problems. I know this from my own issues with my stove (Mark I).
Wood requires a lot more draft then coal, If wood burned well using the chimney, coal should burn fine. The Harman manual specifies a draft of -.06" to -1.0" WC, I'm running at -.05" WC.

Ok my bad here I need to give more info and learn to tell time we are say at night burning from 8-9pm to 5-6am shaking twice a day right before we load new coal. we have the damper turned 3 turns out tried less but it slowly dies out, as for the coal were burning blaschak pea coal and we tried some other coal that looked like a mix of nut and other sizes. Would stove coal burn better for use since there would be more air space..... and the stove is on ground level.

Have you verified the draft readings with a manometer or are you going by the setting on the baro damper?

Are you running the fire up prior to shaking it and loading fresh coal? You should always have a vigorous fire before attempting to fiddle with it. Shaking and loading a cold fire will kill it. The effect would be worse with pea I would think.

I always open the ash pan door and rev it up 2-3 minutes at least before maintenance.

This sounds a lot like the problem, which I "had".

In looking at the pictures, I don't see anything wrong, .... except, I would add a pipe draft. I think, with no manual pipe draft, in an "idle situation", the heat is sucked up the chimney, thus reducing the combustion area temperatures to the point the fire won't continue to burn.

Since I've added the manual pipe draft to my system, I've had pretty good results. All of the old stove set-ups had pipe drafts/damper. I don't feel that a baro damper on a coal burner is much more than a "safety device", as nothing is going to respond instantly to a wind gust or an instant start, as you would have with an oil burner.

Wood'nCoal wrote:Have you verified the draft readings with a manometer or are you going by the setting on the baro damper?

Nope I don't have a meter (ya could recommend some I appreciate it) just goin by the idiot number of the damper.

coaledseat wrote:Are you running the fire up prior to shaking it and loading fresh coal? You should always have a vigorous fire before attempting to fiddle with it. Shaking and loading a cold fire will kill it. The effect would be worse with pea I would think.

I always open the ash pan door and rev it up 2-3 minutes at least before maintenance.

Nope I haven't tried that but I can assure you we'll try it and see what happens.

dallas wrote:This sounds a lot like the problem, which I "had".

In looking at the pictures, I don't see anything wrong, .... except, I would add a pipe draft. I think, with no manual pipe draft, in an "idle situation", the heat is sucked up the chimney, thus reducing the combustion area temperatures to the point the fire won't continue to burn.

Since I've added the manual pipe draft to my system, I've had pretty good results. All of the old stove set-ups had pipe drafts/damper. I don't feel that a baro damper on a coal burner is much more than a "safety device", as nothing is going to respond instantly to a wind gust or an instant start, as you would have with an oil burner.

Ya know dallas the old stove had a manual damper and I guess we'll have to give that a shot. The old would stove you could never keep wood in it you could pile it full and in 6-8 hrs it was all gone.....


again thanks everyone this give some more thing to go on.

If you are seeing 3-400* temps on the flue pipe measured with a magnetic thermometer, you are running the MarkII near full output. The gas temps inside the pipe will be 1-200* higher. Three full turns open is essentially wide open

If you have a strong draft, you should be able to turn down the air vent in the ashpan door, [completely close the vent in the loading door!!] and get your flue temps down to ~200* and get several more hours of burn time out of a full load of coal. Looking at the photos of your chimney, you are really at a minimum for height. The problem is that the flue enters the masonry chimney about five feet above grade, so you need to subtract this from the overall height, so you really only have about 10-12' of chimney. In warm weather, with a cool fire, draft will be minimal.

Recovering a burnt-out coal fire is a slow process, the remaining coal is usually mostly embers, not really burning, but still red hot. Trying to get fresh coal to start burning from these embers can be 'iffy' at best.. Try to catch the fire when it still has some flames off the coal bed, and like coaledsweat said, open up the ash pan door, to 'rev up' the fire, add some fresh coal over the whole firebed, let it catch [lots of fresh blue/white flames] THEN shake the ashes out from under the fire.

Shaking first disturbs the air passageways around the pieces of coal, and can cause a fire to all-but go out. [been there]

Learning to be a biological stoker unit takes a bit of learning...

Does the baro damper open much when it is windy or when burning hot?? if no this is an indication of low draft.

Greg L

Ok we'll I started today at lunch time appling what I've learned and things seem to going better but time will tell altho I did take my heat gun and measured the side and top at a average temp of 400F.... is that good?

Hey U--

If you are burning stack temps at 500F for a few hrs, you burnt out your fuel. ( as others have said )

Start from scratch, build a good hot wood fire using hard woods. Through one shovel full of about 5lbs on top of the red wood ambers. Keep your ash door open. 10 mins later add 10lbs. 15 mins later add 10 more lbs. Basically, establish a good coal fire.

Once you have all fresh coal piled up on your fresh fire, look for the blue flames dancing on top. This is the tell tale fact that lets you know you have a live fire. Close the ash door, open your damper no more than 2 full turns. Let her simmer. Your stack should be no more than 150F. If it is, throttle her in a little tighter ( less air ).

But I have one other comment that many others on this board will not agree. Your flue diameter is too large. Back draft may get heavy and kill your fire after 4 hrs of simmering. You were burning so hot, this problem hasn't occurred yet. But the good news, The colder it is, the better it'll work for you with a 8" x 10". Harman calls for a 6" for your stove. A 6" liner will work wonders.

[quote="Cap"]

But I have one other comment that many others on this board will not agree. Your flue diameter is too large. Back draft may get heavy and kill your fire after 4 hrs of simmering. You were burning so hot, this problem hasn't occurred yet. But the good news, The colder it is, the better it'll work for you with a 8" x 10". Harman calls for a 6" for your stove. A 6" liner will work wonders.[/quote

Actually, I agree. I missed that when I read the info about the set-up. It's also an exterior chimney, which will cool off faster.