Coalpail.com Forum

Harman mark owners,
What do you set your primary air knob at? What size coal are you burning in it? I have a Mark 1. Last season I burned pea coal but I switched to Nut coal because I heard that is the best coal for this stove. With the Pea coal I ran the primary air knob at 1.5 turns out and I had a bit of a learning curve to the nut coal. Right now the knob is about 7/8th turn out, so not even 1 complete turn out.
Tell me about your experience....

When I had my Mark III hooked up & running, I burned nut and would have the spinner open between 1/2 turn and 1.5 turns depending on how cold it was. I think I occasionally had it open close to 2 turns, but that was with a load of dirty coal, a lot of fines, dirt & gravel.

I've had both the I & III. The I didn't require as much air as the III does -that's to be expected. More fuel needs more air. Like a big block vs. small block ... or a Focus.

I usually run my III at 2 turns out, but this will vary with the coal size, and how much effort I put into shaking down. Draft also has an effect on how far you need to open it. Lots of variables. I always burn nut, but the size varies quite a bit in the bags due to handling. It's a looooooong ride to MA from PA!

This morning I had it at 2.25 turns out ... but as the outdoor temp climbed I eventually kept it at 1 turn. I wasn't able to do this before. I cleaned my chimney for the first time ever this spring, so it's pulling double the draft plus some. Big difference that made.

If you have a baro damper installed and set up correctly, you should be open bout 1.5-2 turns. Without a baro, anywhere from .75--1.25 turn. Baro controls your draft thus you have the door damper opened wider, the baro will compensate for you by reducing your air flow up the flue through the door damper. When the air is little warmer and damper, you will open more, cold & dry you will close more.

SMITTY wrote:.... Lots of variables.

Too many to count really... what's the outside temperature, how well is your house insulated, what kind of draft do you have, do you have a barro installed, how well you shook it down, how much heat do you want to produce and how fast? The list goes on and on. Me, I barely open my air valve 1 full turn and it's mostly 1/2 or less but I live in Northern VA in a well insulated house and an average temperature of *27 and a draft that could suck a small child up if I let them get to close. I've been burning coal in my Mark II now for 5 years and can pretty much pinpoint the room temperature I want by opening or closing the air vents (Thank you members of the Forum.) Whether or not it's nut or pea coal makes no difference, I use the size that will give me the best burn for the outcome I want I.e. a long slow burn over time or a quick take the chill off burn. The way I learned this was by burning over time and logging what I did and the outcome. I don't do that anymore but it sure helped me identify the results of my actions, positive or negative. I have a record going back a good 3 1/2 years so I never have to reinvent the wheel to set my stove. If I have a problem, I just look through the log and find a similar situation. As my family will tell you there are two things I'm OCD about (obsessive-compulsive disorder), my coal stove and my bees. Anyway, good luck with your stove, you are going to love the heat. Lisa

Oh I do love the heat. Going on season 3 right now, season 1.5 with the Mark 1(got it half way through last season). Its a good little stove. I need to get 9 hour burns out of it between loads, not hard to do.

When I ran a MK III I used nut at 3\4 to 1-1\2 depending on how much heat I needed, it really liked 3\4 and would burn 24hrs hands off.

Pea I would run 1to 1-3\4, it burned as well as the nut, the temps were a little lower.

Bk

!/2 to 3/4 open, burning nut coal, but remember I use my hand-fed as a radiant heat source in this drafty old barn once winter really sets in. The EFM boiler is plumbed to a heat exchanger in the forced hot air system. The hand-fed evens out the temperature in here nicely.
Before I installed the boiler I was usually running the stove about 1 1/2 turns open.

Just to add to what I said in the other thread:

My particular set up has a 23' external masonry chimney on the east end of the house so keeping it warm and drafting is a constant challenge.

I run the a barometric damper because the house faces south and I am near the water so I get an occasional breeze that will pull hard on the stove and that's the type of thing that messes up burn times.

Right now, it's 57* outside and 74* inside burning nut coal at 3/4 turn open. I haven't touched the shaker handle in nearly 24 hours but I did through a couple shovels in around midnight last night before bed. I really ought to drag my lazy butt down stairs to tend it and turn the air back a bit because it's going to be warm today.

How often are you shaking the ash? I found that was one thing that really shortened my burn times. I wasn't letting that layer of ash to build up where it would just sit and idle.

I admit that with pea, you have to tend it a little more or it will choke itself out but with nut, let it go longer than what you had been doing.

I burn stove coal if it's really cold and the gaps in between those pieces are so big, it's almost impossible to choke it out with ash.

Another thing I do is to take the ash pan out when I'm running. I only put it in there if I'm going to shake the ash. The area below the fire is equivalent to your lungs. It's how you take in air. And if your lungs are half full of crap, how well do YOU operate?

Plus, I don't like the idea of the pan acting like a baffle right behind the intake. I know it operates with the pan in there, but with this chimney, I need an unobstructed air path to keep things moving.

Ive been shaking ash out once a day typically.. I burn less than a bag a day so I consider that good. Today we are supposed to get a high of 65 degrees, which is way warmer than I would normally run but its only a two day warm up then back to the cold tomorrow. I don't want to restart the stove so I am trying to get through today but with temps getting up to 65 or higher, I don't know if it'll make it. Stove struggles to stay going with a warmup like this because there just isnt enough draft.

Currently I have been around 1/2 - 3/4 turn (200 - 300 deg) and tending stove once a day. I rarely go over 1 1/4 turns. My baro is set at .06 and I am heating a little over 2,000 sq ft.

I have a Mark II. The barometric damper is set at .06. My air knob is between 3/4 of one turn to 1.5 turns open. Any more than that and it is over-firing.
I use pea coal. I think it is easier to handle and easier to scoop into the stove. It flows like water where nut coal flows like bricks. You will read lots of opinions on one versus the other. For me, pea coal was best.
A side note, pea coal is easier to obtain. When they are out of rice and nut coal, the pea coal bin is still full. Someone on the forum said that pea coal customers are about 5% of the total. It makes a difference when coal is in short supply. Of course I get my 8 tons in July when there is never a short supply!

So far about 3/4 turn open. Sometimes a little less when the house became too warm. Shake and fill every evening. Burning a mix of egg and stove coal. I also have some nut coal further back in the bin.