Refreshing the Coal Bed

Since I'm not living full time (yet) at my house with the wood/coal furnace, I only get to expand my learning curve a few days per month. Thanks to this forum, one of my minor annoyances is resolved! I've gotten pretty good at achieving a 12-hour coal burn, but when it is time to shake & refresh the coal bed, I didn't like the furnace going "cold" (below 200degF flue temp) until things finally got going again, which takes awhile. Someone, somewhere on the forum, suggested shaking, emptying ash pan, then putting several wood pieces on the remaining coal bed to get things stoked quickly. Did that this morning here in the U.P. of Michigan, where it's still rather cold, (low 20s to high 40s) and we're expecting 3-5" of snow tonight!! Shook last night's 12-hour old coal bed, emptied ash pan, added some split wood, and got a great heat generating fire in minutes. Waited about an hour for the wood coals to establish, then shoveled on the coal and she took right off.

Thanks again, forum members, you're suggestions & other experiences are great!

Hey Dennis, your on your way...

Very unlike wood, coal burning is a balance. the time of year and amount of draft thru the coal,chimney, is the key

My thought is your shaking to much ash out as well as loading to much coal on at once.
it is tough to wrap your head around not shaking out all the ash and loading a bunch of coal on, a wee bit of ash helps the flow sometimes and a layer at at time helps it catch quicker.

the cold black rocks don't spontaniously combust as if thier emmitting volitile fumes as fast as we would like, rather they get hot from heat transfer of the already glowing rock and slowly reach the fuming stage at which the blue ladies dance.

so some pics might help us help you....

Outstanding.Dennis,put where you're from in your avatar/profile so we can just glance over--I know it Mich--profile just makes it easier I guarantee nobody'll will steal ya. --and yes--less shaking--just look for some red embers in the ash pan

Thank you for the insights & comments. I am trying to make sure I don't shake down too much, for the reason you cite of having SOME ash between the grates and the coal bed. I've attached a picture of my "typical" fire (although for this picture I didn't have the box filled up to the top of the first row of firebrick, yet!). The past two days have been great here in the U.P. of MI. I have hit a sweet spot. I've been able to maintain a very consistent 550-600degF flue temp, a really nice looking coal bed, and a very comfortable 75degF house temp. Actually a bit warm, as I keep my full-time house at 67degF with natural gas, so this is really nice!! Baro is set at a rock steady .03in and everything is firing nicely after my shakedown this morning @ 6am.

There is no too warm--that's why there are window-stats If you put your location in your profile, you wouldn't have to keep typing it. Keep that fire-box filled.

nice pic! that seems like a high stack temp tho.... the .03...is that what the weight is set at or are you measuring it with a manometer?

DennisH wrote:Thank you for the insights & comments. I am trying to make sure I don't shake down too much, for the reason you cite of having SOME ash between the grates and the coal bed. I've attached a picture of my "typical" fire (although for this picture I didn't have the box filled up to the top of the first row of firebrick, yet!). The past two days have been great here in the U.P. of MI. I have hit a sweet spot. I've been able to maintain a very consistent 550-600degF flue temp, a really nice looking coal bed, and a very comfortable 75degF house temp. Actually a bit warm, as I keep my full-time house at 67degF with natural gas, so this is really nice!! Baro is set at a rock steady .03in and everything is firing nicely after my shakedown this morning @ 6am.

Your flue temp is WAY too hot.

Measuring draft with a manometer. Weight adjusted accordingly. For Lobsterman: What is a good flue temp for a whole house furnace? I called manufacturer rep in February and he said anything under 700degF, especially on very cold nights, was good. I have a probe thermometer inserted into the flue, so I'm quite sure it's accurate. I'm heating 2500 sqft. Thanks in advance.

Probably the reason your flue temp was perceived as high is due to the fact that you are using a prob. most people just measure flue surface temps. I can't say if it's high or not because I've never used a probe.

if the probe is right at the breech, temps can get quite warm. the common measurement is done as Pete say's with a magnetic thermo, stuck up the stack a foot or so.

using a pair of magnetic thermo's, one at the breech and one on the stove top, I have been able to analyze the different readings of each and thier relationship to each other as I made experimental changes to the draft and feed air as well as different times of year and cold coal load AND

after a while become able to see clearer the "balance" points of those variables....

Where is the chimney probe located? Before or after the Baro?

dj

I've seen flue temps that high with my probe thermometer only when burning wood. The normal flue temp with coal is between 250 & 300 measured with the probe before the baro about 18" from the top of the stove. The flue port on my stove is lower than your though so that probably contributes a bit to the difference.

My probe thermometer is located before (beneath) the baro draft control on the flue pipe. I also have a surface mounted magnet thermometer stuck on the outside of the flue pipe, right next to the probe thermometer. When the probe reads 600degF the surface magnet on the outside of the flue reads 275-300degF,

DennisH wrote:My probe thermometer is located before (beneath) the baro draft control on the flue pipe. I also have a surface mounted magnet thermometer stuck on the outside of the flue pipe, right next to the probe thermometer. When the probe reads 600degF the surface magnet on the outside of the flue reads 275-300degF,

It does seem a little on the hot side. How far from the stove is the probe and baro? Others here will know a lot better than I do if the temp is too high or not... I don't measure my flue temp, but at 12 " behind my stove exit, I can lay my hand on the flue pipe and leave it there in light use. In mid-winter at full bore, I can put my hand there for maybe 2 seconds before it's too hot to the touch. I don't think I could do either at 275, that's well above boiling... I do have a manual damper at 6" from the stove flue exit so I'm touching the pipe 6" past that...

dj

Dennis,I run a probe that is 3" above the stove outlet and sometimes at reload it will go 900' with no problem and my other thermometer is at the same hight as the probe but on the outside of the pipe never goes above 450' (thats my limit)but thats for a short time only and only during a reload, it runs around 300 to 350' (the probe reading is 50 to 75' hotter)at a steady burn with the stove around 450 to 500'.