Need help understanding manometer

I have a Harmon Mark I coal stove. This is my 3rd season operating, after running a wood stove. I finally got a Dwyer Mark II manometer hooked up. The manual recommends a draft no higher than .06. I can keep it under .06, but only when my barometric damper is wide open. I tend to keep my draft knob open two spins, but I am still losing my fires. The temps are hanging in the mid to upper 40's, but still reaching 50-60 degree days. I'm not sure what I am doing or how to make improvements. Any advice would be appreciated. I will attempt tp post some pics to help clarify. Thank you in advance.

I just read the manual and they say the draft should be adjusted in small increments up to 1 full turn.

My old Mark I and the new Mark III both ran fine at .04" and lower. I recall the manual saying the stove required a MINIMUM of .06" - they say that for liability reasons. .06" is more than enough.

As far as not burning through the night, could be a number of things. Coal quality, intensity of burn, possible air leaks around gaskets, or draft strength. Sounds like you've got plenty of draft there, so I'm gonna say at 2 turns out, your really cranking the fire hot. In these warm temps, even I don't have mine 2 turns out (all the regulars here know of my legendary icebox ... and swamp .. of a house). When you run it hot like that, the ashes eventually block all airflow to the fire .... or the coal just plain gets used up. I'd try one turn and see what happens. I never follow the manual - you have to experiment and find what works for your chimney and your comfort level.

I used to run my old Buderus hand fed with no baro, and would monitor the secondary air by watching the way the blue ladies would dance. The secondary air control on that stove was minimal, but also air came in through the glass area as well. The glass was segmented as well, and allowed air in with small vents along the bottom where the glass was retained with a metal rail. Back then a manometer was not even mentioned let alone a barometric damper.

Haha I've been waiting for a response and just realized i needed to refresh my page! So I feel like if I close my draft knob to only one turn open I will definitely lose my fire. I also feel like the stove is not putting out as much heat as I would like. In the past I have cooked us out of our home and now it doesn't get as hot, would like to find a middle ground.

Smitty I think you are right though about the ash eventually blocking the air flow. I have dancing blue ladies at the moment and am afraid to turn the draft knob back. I have built more coal fires than I ever care too! I just want to keep my fire burning.

mseymour wrote:Smitty I think you are right though about the ash eventually blocking the air flow. I have dancing blue ladies at the moment and am afraid to turn the draft knob back. I have built more coal fires than I ever care too! I just want to keep my fire burning.

Yes the ash build up will kill you. You have a rocker grate, so short jerking motion should be the way to go, unless you have white ash coal which will not clinker up as much, and you can probably shake a little more vigorous. How often are you shaking the stove.

Well I originally thought I should once in the morning and once at night, but I keep losing my fires and have been doing some research and saw i can shake up to 6 times a day. Being a former wood stove user, I am trying not to mess with the fire too much

I agree with Smitty, ash build up is choking the fire. Losing fires, not much heat output are symptoms of ash or low draft. Your draft is a little strong so that isn't it.. You can tame that draft down more with a manual pipe damper between the stove and the baro. By using both you can achieve a lower draft and the baro will still take the spikes if its windy.

As for shaking, shake till a good amount of orange embers are falling into the ash pan and you have a nice glow radiating down thru the grates twice a day when you re load.

What size coal are you using? Is there a lot of fines in it? Fines will choke it too if they are excessive.

Do you have the firebox completely filled with coal to the top of the firebrick? Reason I ask is that your avatar pic definitely needs more coal than shown there.

Also on the harman's the ash will build up at the front of the firebox and the fire would not burn as well there. The rocker grates would just not clear it very well there. about once per week i would take a poker and drag it along the front firebrick during the shake down process to clear it of ash.

Check the rope gasket around both doors. If it hasn't been replaced in 2-3 years it is probably time to do so.

Twice a day shake down should be enough.

Oh yeah, good call! I run my coal bed 12 inches deep. Mound high in the center.

Hello. New here, to posting at least. Thanks to all on this forum I've been able to heat my 1200 sq. ft. house after my furnace failed 3 years ago. I also have a Harmon MK 1. It's been a fine learning stove and I probably at this point would get something different, but my house is more comfortable during the winter then it's ever been. The first few months with it, I read this forum like a novel searching and trying new things but finally was in dread that I'd made a horrible decision. My fire would, as yours does slowly dwindle and my house would cool. My solution eventually was extremely aggressive poking. After all the admonitions to not bother the fire I had to start moving away from what wasn't working. This little stove, in my situation at least produces somewhat large quantities of clinkers. I finally had to settle on poking through the bed from the top maybe 20-25 times and also clearing the sides. Then I shake until I feel the crunch of the broken clinkers being ground,( up to 100 X ). My shakes are in an extremely narrow arc to avoid dumping which is the reason for the large number. Nothing less works. The whole noisy ( twice a day )process takes 5 minutes and I can then generally layer the fire back up with 3 ice cream scoops full within another 15-20 minutes. As gets said constantly here, every setup is different. Good luck and thanks again to everyone here.

I use chestnut size coal and I do pack my stove full ( in the pic I hadn't figured that out yet). It seems to be a good quality coal, as I know several others that use it and get good results. In the morning for a reload, do I put new coal in first and then shake it or the opposite way. I have been wanting to poke through the coal bed like Josephk recommended, but I haven't because it is advised not to. Last night I took smitty's advice and opened my draft knob only one turn and this morning I still had a fire! I am reloading with coal as I type, but it still doesn't seem to be putting off a lot of heat. It is about 27 degrees right now, but it's supposed to get to 50 degrees later today.

Sounds like you are on the right track after last night....
With my mark III i always followed the following, you will most likely need to tweak this process to fit your stove/chimney personality...

in morning, open ash door to liven up the fire for a few minutes

then shake down til i saw glowing red reflected in ash pan area

then add new coal - full load, except for leaving a corner of exposed red coals, leaving ash door open for about 5 minutes tops....take a timer with you so you don't forget

close ash door and open loading door to ignite volatiles on top of coal bed to get blue flames

close loading door and make sure blue flames stick around

if blue flames persist then add coal to exposed corner and close it all up.

Evening was about the same process, but usually coal bed was still pretty lively at that time.

About once per week i would run the poker along the front edge of firebox against the firebrick to clear that ash.

two spins open is as far open as i ever ran the mark iii, usually i ran it 3/4- 1.5 turns open depending on outside temps and wind. at two spins it would go through the coal pretty quickly.

what are your stove and flue pipe temps and how and where are you measuring them?

I have a magnetic thermometer on the front left corner of my stove, by the top of the door. When my fire is burning well it is always in the safe zone around 450 degrees. I don't get high unsafe temps since installing the manometer. I don't really measure the flue temp on a regular basis, but last night I had tried it and my flue was around 275 below the barometric damper and 175 above the barometric damper. What would I use for a poker to clean the front wall of my stove?