What causes Hard ashes?

[Blkbeard]

Hi everyone this is my first year burning wood and things are going well (except the size of my woodpile) and up until recently I had just regular ashes and unburnt coals. Now over the last week or so I have noticed a hard almost crystalized ash in my firebox that comes out in large chunks. I am trying to think of what I have changed and the only thing I can think of is I am burning hotter with my fan on High. possibly more softwood too. Are these a result of an improper burning technique that I have picked up? Bad wood? Any insight would be appreciated.

Thanks,

Regency 1200i Insert
burning assorted wood ( some not as dry as many of you would recommend.)

 

[jtp10181]

I would think it could be from wood with too much moisture but that's just a guess.

If anyone knows what can cause it exactly I would like to know also. I think its what sometimes destroys my customers pumice bricks from Quadrafire.

 

[bokehman]

Now over the last week or so I have noticed a hard almost crystalized ash in my firebox that comes out in large chunks.

Sounds like clinker, but I thought that was a by-product of coal fires.

 

[begreen]

I think there is an amount of silica in many wood species. You see this a lot in pellet stoves where wood is burned furnace hot. When a good, hot coal bed is established and a high silica wood is burnt, the silica seems to fuse into these clinkers. I've aslo read there are calcium and aluminum oxides in some wood. With the Jotul, I get a fair amount burning soft maple 24/7. The wood was lying on the ground for a year so it may have picked up additional sand and dirt there too.

 

[dsil]

I believe the stove needs more roughage

 

[begreen]

Home Fire Prest-Logs has this info on their site:
"Clinkers are the result of ash fusion, where noncombustible salts and minerals entrenched in the wood fibers liquefy and bond together."

 

[wg_bent]

Much higher rate of these with elm than any other wood. Just one more reason to hate that crap.

 

[Blkbeard]

Thanks alot I had never heard the term clinkers before and since its natural then I am not doing anything wrong which was my main concern. I just must be in a different section of my woodpile and the wood thats there is causing these things. Not that its really important I just wish I knew what type of wood I was burning so I could share that information with you.

PS as a new woodburner here is a tip I had never read about in these articles. When starting a fire with my stove I need to keep the door cracked initailly for extra draft. With the stove packed full I was always concerned that during settling of the new fire that a log would roll against the door and push open the door and out onto the floor. I have found out and I am not sure if this is by design, that if I turn the door lock from the normal anticlockwise postion to lock the door all the way clockwise that the door will lock to prevent unanticipated openings but remain unsealed to allow the extra draft. Hope I explained that properly.

Thanks again for your help

 

[savageactor7]

good topic...sometimes I get those hard cliker like clumps and could never figure out why. Since most of the ashes go in the garden it was really no big deal...but now I know.

 

[hookspacken]

I experienced some of that this years as well. Glad someone asked that question as I was wondering.

 

[paulie]

tell me BLKbeard, do you have a off set adaptor on that Regency 1200? I do, and it wasn't secure to the box " bad install" many times they will just hang it and slide the insert on to it. this caused me a dratf issue, I had to also leave my door open to get extra draft, when starting, and reloading. fix the problem, and now can shut the door with in just a few minutes of a new load,and a full reload, air fully open, and it burns GREAT talked to regency and the have had a issue with this type of install, it was common place to install in that mannor.

 

[jebatty]

Aspen/popple has a lot of calcium in the bark, and it also produces hard ash clinkers.

 

[jeffman3]

I'm burning elm almost exclusively and I am getting clickers as well, I notice them most after a hot burn. I decided it must be a result of the intense heat, and the elm I'm burning. BTW I love burning elm, beats the heck out the cottonwood that is my other option. ;-)

 

[woodconvert]

Not properly seasoned wood. I get that when i'm burning ONLY from the bottom couple of courses of my wood stacks. Lately i've been setting a lot of that wood in front of the stove on end to dry it....it works. No more "clinkers". Oh, and i'm burning red oak at the moment.

Note: When you dry wood this way...depending on the moisture of the wood you can get some ginchy stuff out of a split.

 

[bokehman]

The quote below explains what is happening. Clinker forms when ash is heated to a temperature above it's own melting point. So, if one uses a fuel that produces ash that melts at a temperature lower than the flame temperature clinker will form.

...Clinker is composed of unburnable minerals in the coal that have been heated to the melting point. Depending on the coal, clinkers can be hard or soft. Soft clinker runs down through the grates, and hangs like stalactites in the ashpan. This is bad enough, restricting airflow through the grates, but is less of a problem than hard clinker. Hard clinker is a glasslike substance that forms in the firebed. This is a real problem, and it can form without warning and spread fast. Once the fireman spots the dark spot that means clinker, the solution is to break it up immediately by rocking the grates. If the clinker hardens, the grates may be immobilized, and the only cure is to reach for the “hook”. In yet another contradiction, the fireman has to adhere to the “light and bright” rule without letting the fire get hot enough to form clinker. The key to preventing clinkers is never to let the unburnable part of the coal get hot enough to fuse into clinker. For this reason, the ash and live coal layers of the firebed aren’t supposed to mix. Thus skilled firemen generally avoid using the slice bar or clinker hook, so that they won’t mix the two zones and cause clinker. But - in another contradiction - the only solution to a clinker, once it forms, is to rake it up and out through the firedoor with the hook. Obviously, finesse is called for as you use a 10-foot-long bar, which is so hot it’s soft, in a six-foot-long cab, to manipulate a 1,000- degree clinker out of the fire and onto the floor of a rocking, lurching locomotive, without stirring up the ashes - and while watching the railroad out your side of the cab. Only rarely will a fireman get a tender full of coal that won’t clinker, and some coal clinkers badly. There may be two kinds of coal in the bunker, which means knowing how to fire both kinds, and how to handle the transition between the two; the mixture is effectively a third kind of fuel with it s own characteristics. The advice of one old manual is, “only enough coal should be added to the firebed to maintain the fire.” The goal was just enough, but no more, without letting the fire get thin or go out in places...

 

[woodconvert]

Clinker forms when ash is heated to a temperature above it's own melting point.

I don't think that's the case...or at least in my situation. Right now it's 38ish and the fire is barely going and I need to chip away at the "clinkers" restricting air flow to the grates. I find this only happens with marginally seasoned wood. When I've got a rippin' fire with the good stuff I don't get the clinkers.

 

[Moddoo]

I have had them while burning elm also.
The wood was standing dead and dry and sat stacked in the sun all summer.
also, elm just seems dirty to me, smoky at start up, lots of ash, clinkers, etc.
I have been burning it plenty hot.

Thanks for bringing this up. I was wondering why I never got any last year. I didn't burn any elm last year.

 

[Blkbeard]

tell me BLKbeard, do you have a off set adaptor on that Regency 1200? I do, and it wasn't secure to the box " bad install" many times they will just hang it and slide the insert on to it. this caused me a dratf issue, I had to also leave my door open to get extra draft, when starting, and reloading. fix the problem, and now can shut the door with in just a few minutes of a new load,and a full reload, air fully open, and it burns GREAT talked to regency and the have had a issue with this type of install, it was common place to install in that mannor.

Yes I had that problem too. Actually there was about a 2" gap at that point it was drawing air above the fire. The problem was probably worse for me since I am new to woodburning. I had no Idea of what is right and what is wrong. Here are the links to me trying to figure it out. And a couple pictures I took at the time.


https://www.hearth.com/talk/threads/9139/
https://www.hearth.com/talk/threads/10073/

I talked to Joe Giannandrea at Regency he was a great help and figured out the problem in minutes. I was discussing with him how I had to build a big fire and leave the door open for up to 20min to at least keep the fireburning and then I told him somtimes I had to shut it sooner since the fire was so large that it started to leap out of the stove and I had to close the door. That triggered him direcly to the problem. Then the problem was trying to convince the dealer what I now knew after I verified it by hand. That company sure was not a One Stop Fireplace Shop thats for sure.

 

[woodconvert]

I have had them while burning elm also.
The wood was standing dead and dry and sat stacked in the sun all summer.
also, elm just seems dirty to me, smoky at start up, lots of ash, clinkers, etc.
I have been burning it plenty hot.

Thanks for bringing this up. I was wondering why I never got any last year. I didn't burn any elm last year.

This is odd. I burn elm in the spring and fall and I don't have this issue. It appears to me that I only get clinkers when i'm burning wood that is not seasoned as well as it should be and like I said...i'm burning red oak right now (from the bottom of a stack) and I get them. Very big puzzlement indeed.

 

[bokehman]

Clinker forms when ash is heated to a temperature above it's own melting point.

I don't think that's the case...

Think of your unburnt material (ash) as if it were snow. If it doesn't ever reach the melting point it will always be snow. If it reaches the melting point and then cools it will turn to ice (clinker). But if you have a really rip-roaring fire not only will it melt but it will also vaporise and be lost up the flue.

 

[Moddoo]

Interesting.
Possibly the trees growing environment/soil makes a difference.