Is 850 F Too Hot for a Firebox on This Herald?

Question about temps...First time running the stove on coal. (It's a Herald similiar to the one in my profile) I'm still new here. I decided to run some coal in my stove this morning to get a feel for things. A small wood fire was enough to light the coal. I added 5 quart size containers of chestnut size coal to the stove and it caught nicely. I dampered it down and it is running at a pretty steady state. I'm just not familiar with a coal fire (though I have read a lot here and watch's William's videos). I was concerned that if I did not get things hot enough at first, the coal might not light.
These are the temperatures on my stove running nut coal from Tractor Supply:
At Startup :
Stove pipe temperature 185 F as the pipe enters the chimney.
Stove pipe temperature is 340 at the location where the pipe exits the stove.
Top part of the stove measures 390F
The middle of the stove's cylinder is 550F
The exterior of the fire pot (area where the coal rests) measures 850F
The back brick firewall temp is 190F nearest to the firebox

After an hour:
Stove pipe temperature 156 F as the pipe enters the chimney.
Stove pipe temperature is 300 at the location where the pipe exits the stove.
Top part of the stove measures 330F
The middle of the stove's cylinder is 400F
The exterior of the fire pot (area where the coal rests) measures 600F
The back brick firewall temp is 150F nearest to the firebox

After an hour and 30 minutes:
Stove pipe temperature 160 F as the pipe enters the chimney.
Stove pipe temperature is 280 at the location where the pipe exits the stove.
Top part of the stove measures 300F
The middle of the stove's cylinder is 365F
The exterior of the fire pot (area where the coal rests) measures 530F
The back brick firewall temp is 145F nearest to the firebox

After 3 hours the fire is really dying out:
Stove pipe temperature 90 F as the pipe enters the chimney.
Stove pipe temperature is 180 the location where the pipe exits the stove.
Top part of the stove measures 150F
The middle of the stove's cylinder is 200F
The exterior of the fire pot (area where the coal rests) measures 280F
The back brick firewall temp is 95 nearest to the firebox

Is that temp on the outside of the the firepot (850F) too high at startup? After about 30 minutes temperatures moderated down. But the exterior firepot temp after 30 minutes was still 600F. The other temps moderated. But am I outside the acceptable range? Do I need to shut the primary air down faster? I could not find many references to the fire box temp in the forum. Most references were for stovetop and stove pipe temps. What temperature are considered a good range to be in? Note: the firebox is not currently lined with a refractory material (a project for this summer). I don't plan running the stove again this season. I just wanted to get a feel for things. It is currently 29 F outside. The damper on the stove pipe to the flue is 3/4 closed. Running CO detectors in the house.

i can not tell you for sure about your stove but I think you are well in the ball park.

you have some very reactionary coal for a test burn, the TSC Kimmels runs hot.

for comparison, I just took some IR laser temps. on my base burner.

firebrick inside of fire pot just above fire 966*

hot spot on outside of stove 324*

pipe going into chimney 101*

the stove has been running like this for over 24 hrs.

i say you have a very able stove and will be pleased with it's operation when you have completed your preparations.

steve

My concern is that the fire would get out ahead of me and I would not be able to wrestle it back down.
I think I read that anthracite burns at 900- 950 degrees and fires run up to 2000. That is serious heat.

My stoves run the hottest when I build a new fire after a good cleaning combined with cold outside temps. As my home heats up and the stove has acquired it's 'necessary' ash layer, (this happens after a couple shakes and reloads), the sweet spot can be dialed in. This is a combination of primary air, over fire air, draft setting's for stoves with or without a mpd, a baro, or both. Generally I try to keep my flue pipe temps at the chimney below 150* and usually near 120* once it's parameters are met.

You have a simple safety valve for excess heat the MPD and load door. Open the MPD and load door and it will shed heat very quickly. If you are there it will never get too far ahead of you that can not be cooled down. If thew ash pan door falls off it will be epic but not much to do about that if not there and if mechanically sound sincerely doubt it will ever happen.

And always remember, if the 'over the fire air' doesn't slow the fire down..........either cover it with ashes, sand, or very fine coal. Any of those will smother the fire.

I would have thought that opening the MPD would increase the O2 to the fire and therefore increase the temps in the firepot.
If I open the load door and MPD, I can dump some heat? Just keep the primary closed?
I will be sure to keep a bucket of sand nearby next time. Once everything settled in I felt like I had good control (there was also not much that I needed to do anyway). But intially, at startup, at first I was concerned that I would not have a hot enough fire to light the coal (stuff looks and feels like rocks to me). At first I was not really sure if any coal was lighting (it was hard to tell). The fire was really not that hot from what I could tell at first. After I closed the door door it started climbing. And then the temps climbed some more. Watching those temps climb knowing there was still a pile of coal (unburnt fuel) in there, I go nervous. I'm still thinking like a wood burner. Opening the load door throws O2 to a wood fire. This is the same picture as above but with the camera's flash:

Yes, opening the load door and opening the MPD causes a direct draft ..........over the coal fire, and out the chimney, which causes the coal to burn slower.

Totally different than wood.

If anthracite burns at 900- 950 degrees, wouldn't that mean that the firepot would have to be up near that temperature to keep the fire going? Once the firepot drops below that temp (900) the unlit coals above the burning ones would not catch fire? Trying to figure out what is not hot enough and what is too hot on those temperatures that I am measuring.
I did notice that once the temperatures started to drop a little the new coals were no longer catching. I ended up with a pile of un-burnt or partially burnt coals when the fire was finally out. I will watch William's videos again, I may notice something that I did not the first time I viewed them.

Anthracite coal likes a nice deep bed of coal to burn properly so you will want to fill that fire pot completely. It would also burn more completely if you line the fire pot with refractory material. When the coals are right up against the cast iron pot, the steel actually will cool the outer layer of coal and it does not burn as well.

You have to throw everything you know about burning wood out the window, coal is a different fuel. It takes a completely different process to keep it going.

Randy

KingCoal wrote: for comparison, I just took some IR laser temps. on my base burner.
firebrick inside of fire pot just above fire 966*
hot spot on outside of stove 324*
pipe going into chimney 101*
the stove has been running like this for over 24 hrs.
steve

This is very helpful information. If there is an opportunity to gather these temps the next time you are starting the stove, I would be curious to see what the ranges are. The transition from starting to running is something I'm trying to figure out. As others have said, a refractory lining and a good pile of coal should help. I just didn't want to pile the coal in there until I felt comfortable that I knew what I was doing.

Underdog wrote:

KingCoal wrote: for comparison, I just took some IR laser temps. on my base burner.
firebrick inside of fire pot just above fire 966*
hot spot on outside of stove 324*
pipe going into chimney 101*
the stove has been running like this for over 24 hrs.
steve

This is very helpful information. If there is an opportunity to gather these temps the next time you are starting the stove, I would be curious to see what the ranges are. The transition from starting to running is something I'm trying to figure out. As others have said, a refractory lining and a good pile of coal should help. I just didn't want to pile the coal in there until I felt comfortable that I knew what I was doing.

i shared this as an attempt to assure you that the temps. you were seeing on your start up were not only just fine for that time but that your stove is capable and will very likely hold those temps. for days and even months once you decide to start using it.

which brings up another point. coal is not all that as an occasional entertainment heating choice. it's a build it deep and hot enough to carry the comfort level and then keep it there choice.

for instance, I started my stove on Oct. 8th 2014 for this heat season. it has not gone out on it's own nor have I shut it down for any service or inspection.

there are things you just can not figure from a short static experiment. take car building, tuning, driving for example. you can start it on the drive as often as you want, even rev it some. that's not going to tell you anything about how it's going to ride, handle, the engine operate or the speed or economy the gearing choices you made are going to work out.

coal stoves are the same thing. you have to do your best to assure that the unit is sound, sealed and properly vented THEN you have to light it up, build it up and run it. a test run for me would have to be at least 24 hrs. of constant comfort level out put, you need steady state parameters to learn anything from.

you've got a real fine stove and i'll bet you'll be fine.

ps, nothing that worked, made sense and was desirable about wood burning means anything toward coal, other than HEAT of course.

steve

Underdog wrote:If anthracite burns at 900- 950 degrees, wouldn't that mean that the firepot would have to be up near that temperature to keep the fire going?

Anthracite's autoignition temp is over 1100*F. 900* is on the edge of going out. What the appliance sees and what the fire produces are different numbers obviously.

Hey 'Dog, how are you retrieving those temps? Are you using an I/R gun, or sliding around a mag. thermometer? Is that 850* during start-up with the wood burning also? I notice my heat-exchanger temp. skyrocket when the flames are screaming at start-up, alto I haven't seen 850*. But my temps are basically exhaust temps, and not fire-box temps. Is your stove hooked to a legit chimney? I'm curious why your fire went out after only 3 hrs? Maybe because not enuff coal? Can't wait to see more pics of your set-up. Is it a BB?
(Bye the way, you're in New England? Would that be "southern" NE?)

joeq wrote:Hey 'Dog, how are you retrieving those temps? Are you using an I/R gun, or sliding around a mag. thermometer? Is that 850* during start-up with the wood burning also? I notice my heat-exchanger temp. skyrocket when the flames are screaming at start-up, alto I haven't seen 850*. But my temps are basically exhaust temps, and not fire-box temps. Is your stove hooked to a legit chimney? I'm curious why your fire went out after only 3 hrs? Maybe because not enuff coal? Can't wait to see more pics of your set-up. Is it a BB?
(Bye the way, you're in New England? Would that be "southern" NE?)

Southern New England, masonry chimney is 38 feet tall (2 story house) with a good draft. The temps measures are all with an I/R gun.
It was my intent for the fire to go out. I only put in 5 quarts containers of coal. I wanted to see how hard the coal would be to light. I wanted to know if the coal would smoke or have a objectionable odor. I wanted to see what burning coal looked like. I was curious to know the temperment of coal and how quickly it responded to changes to draft. The I/R gun was handy to get some idea of what was going on with the stove and how it would behave when running coal. My first impression is that coal behaves very differently from wood (as others have mentioned) and that the stove is far better designed to burn coal than wood. Odd that the previous owner lived with this stove for 90 years and never mentioned coal. He had a nice stack of small dry wood ready to use. We really only used the stove during power outages because the flue is shared with an oil fired boiler (shut off when the stove ran). The new boiler that's coming this summer will free the chimney up.