Not Enough Heat...

I started burning coal in my Harman Mk III about a month ago. I started out using nut coal. I didn't have any trouble getting a fire started or maintaining it (thanks to this forum). But I wasn't happy with the heat output compared to what I had been getting with wood. I was happy with the length of time between "messing" with it. I had only bought 10 bags of nut coal. When this was gone I burnt another face cord of firewood. Then I bought 10 bags of stove coal. I have been happier with the stove coal, but I still like wood better. I am using a baro set at .06" vented into an interior masonry chimney. The stove is in my basement and I'm heating 1,200 sq.ft. Airflow is not the issue, because I get good results with wood. I am able to get wood for $55 a facecord already split. At this point, COAL SUCKS. Unless I can figure out my problem, I'm going back to wood. Any suggestions?

If the heat output started out fine but has gotten much worse (over time), I think your problem is too much ash in your stove.
Try this thread: More of a Mid-Winter Cleanout Than A Shake Down

It really hasn't been satisfactory since the beginning. Everywhere I've read that coal produces twice as much heat as wood. I would like to know who came up with that idea.

I've not had a problem with losing the fire, and I shake my grates atleast twice a day. When I shake, I also poke up from underneath until there is an orange glow throughout the entire ashpan. I discovered right away that shaking until a few coals drop is NOT enough. I forgot to mention that I'm using Blaschak coal, not some unknown garbage.

4570FAN wrote:I've not had a problem with losing the fire, and I shake my grates atleast twice a day. When I shake, I also poke up from underneath until there is an orange glow throughout the entire ashpan. I discovered right away that shaking until a few coals drop is NOT enough. I forgot to mention that I'm using Blaschak coal, not some unknown garbage.

Some think Blaschak is the lower end of the coal quality spectrum.

My father started off burning Blaschak in his Mark I, & when he switched to Kimmel's , he said there was a dramatic heat increase. Could be the coal, or you might need to crank the damper open more. Get that pipe up around 250* - 300* & it should cook you out.

The MarkIII will heat that space with coal no problem.
Usually a lack of heat with a 'good burn' means too much draft.
You are filling to the top of the bricks, yes?
Body of the stove 300-450*?
Have you verified the draft with a manometer or are you just using the marks on the barometric damper?
No creosote on the barometric damper?
Pictures of the setup will do wonders for finding a cure to the problem.
Blaschak is consistent and is a good benchmark to eliminate variables when there is an issue.
There are different coals that may burn better for your conditions but Blaschak seems to be one of the better bagged coals.

4570FAN wrote:It really hasn't been satisfactory since the beginning. Everywhere I've read that coal produces twice as much heat as wood. I would like to know who came up with that idea.

If your draft is ok, your house is not too air-tight for enough combustion air & you are filling your stove up to the tops of the firebricks then I can't imagine how your stove could not be putting out a good amount of heat, even when first lit???

4570FAN wrote:Airflow is not the issue, because I get good results with wood.

In actuality, coal needs much more air than wood to burn well. Try opening a window in the stove area to see if that helps.

How long is the burn time? After you load it up, how long before you add more coal? Do you have a magnetic thermometer so you can tell us how hot the stove pipe is (before the baro damper) at mid burn cycle?

My house is about as airtight as a sock! Actually though Devil505, I was referring to heat distribution. My baro has been verified with a monometer. I'm sorry, but I am unable to provide any pictures. There is a 90 coming off the back of the stove with it's outlet at a 45 deg angle from verticle. Then there is 24" of pipe to my tee with the baro. The tee is connected to a 45 into the chimney. I am currently running the draft spinner at 3 turns open. I have a pretty good fire going now. The flue gas temp is 225 after the baro. I am going to try turning down the fan that is sucking air out of the basement. Maybe I am causing "negative" pressure down there. Thanks for all the ideas though guys.

maybe it is the coal? im new to coal also and the last load of coal I got was different than my regualr stuff and it burns at a lower temp, my new coal burns with a yellow flame the old stuff I had burned with a blue flame. I also have a mark III and it keeps my house toasty, I have no baro and run the ash door vent 1 turn open when im at work and about 1 1/2 to 2 turns when I want to warm things up

3 turns out is quite a bit! Especially if your chimney is pulling a .05 or more. My chimney averages about a .05 & on warmer days I run the stove at 1.25 - 1.5 turns out. Today is in the 20's outside (teens this morning) & I have it at 2 turns. In the single digits, I had it at 2.25 .

You need a stack temp. to determine if that setting is too much. If it's burning too hot, most of the heat will go up the chimney & rapid ash buildup on the grates will choke the fire way down. In that situation, not much heat makes it into the house.

EDIT: just re-read your post. 225* AFTER the baro is very hot..... this may be the problem

Too much air sucks the heat up the chimney, typical word burner mistake.
Cut the spinner to 1.5 turns and you should start making heat.

.06 seems high on the baro. Most people here use .04 as a base line. I shoot for between .02 and .03 as my chimney will
suck the chrome off a bumper.