Boom!

lowfog01 wrote:I open the ash door, set the timer and wait until the blue ladies to start their dance. Well, a couple of times it's taken forever for the coal bed to recharge (10 - 15mins) and when the blue ladies finally show up it's been with a mighty whoosh and a pretty big puff back. The ash door has been pushed further open and flyash has gone everywhere. I have not added any new coal at this point. I’m just waiting for the coal bed to get hot and the blue ladies to start dancing so that I could actually mess with the fire. That's the first rule right - only mess with a strong fire.

Has anyone had this happen before?

Yes...It has happened to me & I really have no explanation to offer. It's kinda like refilling but nothing has been touched??
What I have done is develop a kinda 6th sense & if the ash door has been open for a while......but still no flames....I will keep opening the load door every few minutes to feed oxygen to the fire to encourage flames b4 a puff-back.
Why it happens....I could guess but can't say for sure

Thanks, I thought I was going nuts. I wonder if it may be in part because of the low draft. Maybe some gases aren't moving out as fast - I don't know I'm just guessing. Lisa

lowfog01 wrote:Thanks, I thought I was going nuts. I wonder if it may be in part because of the low draft. Maybe some gases aren't moving out as fast - I don't know I'm just guessing. Lisa

Sounds very possible!...The gases aren't being pulled out of the stove so they just accumulate until hey ignite!...I like it!!

OK, I am far from an expert in this area, but really, the name of the stove IS:

H O T B L A S T

With a dynamic name like that couldn't you expect a thermal event like this?

".....BOOM! what the *&$#%*$# was that the mrs asked. went downstairs and the ash pan door that was cracked was blown right open and a 15 foot stream of ash on the basement floor from out the ash door. guess I was loading....."

Everybody's in one piece....that's what counts at the moment!

Bob

I'm never happy/relaxed with the ash door open UNTIL I have sustained flames. I'll keep working on it (opening the load door, opening secondary air vents, throwing a bit of newspaper on top, etc) until I have flames. Flames = No Booms
No Flames= Booms!

Devil505 wrote:Flames = No Booms No Flames= Booms!

Bank the fire, booms be rare.

Devil505 wrote:I'm never happy/relaxed with the ash door open UNTIL I have sustained flames. I'll keep working on it (opening the load door, opening secondary air vents, throwing a bit of newspaper on top, etc) until I have flames. Flames = No Booms
No Flames= Booms!

Yes, I do the same as Devil. (Well, no newspaper....) But the only booms I have had were after loading new coal. Never when trying to freshen up the fire with more air after a long idle, probably because by then the coal bed was 80 percent burned and most of the volatiles had previously been driven off. If you have that much fresh, untouched, volatile coal after a long idle, you could perhaps extend your idle another 12 hours before tending it.

This always happens more at the end of the season, when the pipe is full of flyash from burning all winter, & the draft isn't what it was at the beginning of the season.

".....Yes...It has happened to me & I really have no explanation to offer.....

Oooh ooooh, This reminds me of the time I got a 106 on a HS Chem test

Combustion is a chemical change, right?
Adding coal to a stove that has been "balanced" in its burning (rapid oxidation process), causes an Imbalance!
That imbalance, as you add carbon, is an oxygen deficit. (As you noticed you're smothering the flames.)
Now rather than having your previous balanced burn, creating Carbon Dioxide, a rather innocuous gas; you are creating CARBON MONOXIDE [a product of carbon, combusting with insufficient oxygen] We think of Carbon Monoxide as a poisonous gas but neglect the fact that it is also FLAMMABLE...And when confined in a closed container potentially explosive...So an instant after the proper amount of carbon monoxide + oxygen+ heat(flame) combine...the ash door flies off with results already noted...

One may also consider that if there is moisture added to the mix of hot coals, the resultant steam on hot coal in an atmosphere of reduced oxygen can create a quantity of "manufactured gas". This gas also known as CIty gas SYN gas or what have you, & can consist of varying amounts of HYDROGEN, OXYGEN, METHANE, & blah blah blah...You get the idea,,When these gases contained in the stove they can initiate an instantaneous oxidation event...BOOM

EMDW

RMA

rberq wrote:[If you have that much fresh, untouched, volatile coal after a long idle, you could perhaps extend your idle another 12 hours before tending it.

I'm going to give that theory a try starting tomorrow morning. I intend to load the stove up with as much pea coal as much as I can and set it to idle while I skip out of town for a family gathering. I've never had a burn that long but I think you're right considering the amount of volatility left in the coal at the end of the initial 12 hours. The weather is going to be cooler and my baro is working well. It will be interesting. Lisa

It's happened to me too

I've read this thread with great interest, as well as the older "minor explosions" thread, since once I got going with my coal fire, I discovered booms!....I am a newbie; finally got my fire up and running last January with the excellent help from you all on this forum!

I found the booms very disconcerting and have had the chimney clean out door blow open. Booms are something I really wanted to eliminate.....but how? I think I finally discovered the system for my stove, a Hitzer 55.

The stove has a number of good features. The internal baffle that improves combustion efficiency has a big 6" diameter hole in it, which is opened and closed by an external control. It is designed to allow a direct path from firebox to chimney to stop smoke coming into the room when you open the loading door. I find the direct path afforded ideal to usher out the volitile gases produced from new coal.

There is a spinner draft knob on the loading door to allow over fire air.

The fire is controlled by a thermostat that mechanically opens and closes the primary air damper feeding air under the grates. It has worked very well and controls my fire within a 20F range. I run my stove around 400F surface temp.

Keeping in mind the advice on this forum to never cover a fire with fresh coal, only tend a lively fire and watch for the blue ladies....I would tend as follows:

Open my direct vent damper, spin open the spinner draft knob in the loading door and open the ash door and wait. In just minutes my fire would come to life and reach 550F, sort of an arbitrary temperature I settled on, as it provided a very lively fire that I could shake and poke and not hurt it in the least!

On hitting the 550F point, I shake and then stoke one side. The temp will drop with the fresh coal and then recover to 550F again at which time I open the loading door, see lots of blue ladies on the new coal on side one, and I stoke side two. Again the temp drops with the new coal and recovers to the 550F point...normally a 10 to 15 min process. Now I am fully stoked, the fire has recovered to 550F and hopefully the volitiles have burned off. I close the ash door.

This is when I'd get booms.....a lot of time. Not bad, but booms that are disconcerting! to say the least. I've got air going over the fire as the spinner is still wide open. I have the direct vent damper open so it's a straight shot up the chimney. I had a vibrant fire with loads of dancing ladies at the 550F point when I closed the ash door......so why the booms? ?

You folks keep saying you need flames to prevent booms! Ok....made me think. When I close the ash door, maybe I am shutting so much air off....as in ALL the air coming under the fire....that all my blue ladies go out....setting up booms. No way for me to watch....no glass door in my Hitzer.

And OK, I could crank open my thermostat to open the primary draft control and let air come under the fire....but then I'd have to remember to set it back to where I run it....yeah, I'm lazy and like it real easy.

A small nail to the rescue! Yep, I decided to try propping the primary draft door open just a crack. A 6 penny finish nail worked like a charm. That lets enough air in under the fire after the ash door is closed, to maintain some blue ladies and keep burning the volitiles. Yet the damper is closed "enough" to bring the fire down to operating temperature. Takes awhile, as in maybe 30 minutes, but I've not had a boom since going to this technique. Once I close my ash door with the nail propping the primary damper open slightly, I can go about my business as the stove is safe....not the most efficient with the direct vent still oen and spinner still open, but safe to leave if I forget it. (I never leave the stove while the ash door is open.)

I'll set a timer to remember to return and improve my stove efficiency by closing the direct vent and door spinner in about a half hour, at which point I'll find my stove at operating temp (400F) and the auto damper has opened slightly to control the fire, which drops the nail out onto the floor and the control is again capable of closing the air off tightly, if need be, but long after the volitiles are burnt off.

I know this doesn't help folks with different stoves but I will stress again to follow the sound advice on this forum. To avoid booms, you must have blue ladies the entire time it takes for fresh coal to give up its volitiles. A direct path out the chimney is a big help. Over fire air is good.....but doesn't make up for no blue ladies if the under fire air is cut off or insufficient.

I think we all understand never to completely cover a fire a fresh coal....even when in a hurry....it's been said you must have patience to tend a coal fire....I found that to be VERY true. Stoking in two steps isn't that bad. My entire process from open the ash door to close the ash door is about 30-40 minutes. Add another 30 minutes to come back and close the spinner and direct vent for efficiency...but I can be away from the stove for that time, doing something else.

My two cents....
Mountainman37

I don't have your model stove but I do not think you are taking advantage of the fact you have a thermostat.

At the end of a long burn the grates are clogged and the thermostat damper should be open to compensate. I would crack open the loading door and give it a light shake. The cracked open loading door will lessen the pull through the fire making fly ash easier to drop into the ash pan and the extra air from the open door will further cool the thermostat causing it to open further. Close the door.

When the fire builds a bit, again crack open the door and do your shake down and load fresh coal. Open the ash door, take out the pan and close the door. Empty the pan, Open the ash door to replace the pan and close it again. Open the secondary air in the loading door for 20 minutes or so then close it.

If you look at the thermostat damper it should be open because you have not overriden it by leaving the ash door open and making more heat than it was set for.

It seems to me this is the way to work with a stove that has a thermostat and allows you to take advantage of it and I don't think you will get any puff backs.

Richard

Thank you, Richard, that technique looks good! I do believe I will give it a try next season; I've shut down already for this season. I rather like the idea of not heating up so hot for shaking and stoking. And eliminating booms are the main thing, of course!
Mountainman37

Mountainman37 wrote:Thank you, Richard, that technique looks good! I do believe I will give it a try next season; I've shut down already for this season. I rather like the idea of not heating up so hot for shaking and stoking. And eliminating booms are the main thing, of course!
Mountainman37

A nice project for the off season would be to add a peep hole to check the state of the fire. You will need two hole saws. 1 1/2 and 2 !/4 inches. Cut a 1 1/2 hole in the door using low speed. Using a piece of 1/16 sheet metal cut a 1 1/2 hole in it, then using the 2 1/4 inch saw cut around the 1 1/2 hole you just cut. This will leave you with a ring with about a 1/2 flange to use as a retainer for glass or mica. Drill 3 or 4 holes to take 10x 24 screws. Mark the door and drill and tap for 10/24. The right size glass might be hard to find so use mica and cut the circle with a scissors while holding it under water. Do this on a scrap piece to make sure you have the technique down before doing any hole cutting. The circle has to be inside the screw holes. Fasten to the door with the screws either inside or outside depending which way looks neater to you. By using larger saws you could make it bigger if you want. Brass or stainless screws would make it easier to undo.

Richard