NC30 coal build up in box

[Highbeam]

I think I finally know what you folks are talking about with this coal build up thing.

I have this stove in my shop and it was well below freezing this weekend and that means that the shop was very cold. I had some plumbing to do so I needed to warm up the shop. The NC is my weapon of choice and it did very well with a box fan blowing on it and me trying to keep temps at 600-700.

I was burning maple, nice blue flames, and I noticed that my firebox was shrinking. A deep coal bed builds up that can't be spent unless the stove goes cold. I tried the old trick of burning off a couple splits with full air and no luck, I needed heat.

Open door fireviewing with that bed of coals is sure a warm experience.

A nice benefit is that this big old pile of coals was still sufficient 12 hours later when I restarted the fire the next day.

Someday I'll get the radiant floor heat hooked up.

 

[Jags]

Now THAT is a box full of coals.

 

[bluedogz]

Boy, that makes me feel better. I've ended up with a box like that a couple of times... I thought I was alone.

 

[begreen]

Maple will do that. And there will be a lot of ash leftover.

 

[Ashful]

That's some interesting plumbing. What's the appliance?

 

[begreen]

Wort chiller and sink?

 

[Highbeam]

That's some interesting plumbing. What's the appliance?

This is a mechanical room in my shop. Farthest left is the 2" drain for a greensand water filter, then a pair of connections for the sink, and then the toilet. It's hard to tell but there are two drain lines out of the building combined to a single vent stack. That dual drain is why I have two sink drains. I wanted to be able to have a sewage outlet for toilet waste and a greywater outlet for greensand backwash. I want the sink to be able to go to either so I have dual sink drains.

The crazy red plumbing pipes are 6 loops of heating pex all connected together for a pressure test.

 

[Highbeam]

Wort chiller and sink?

You bet. The wort chiller is one of those devices that will dump lots of clean water and I can finally do it all from inside the shop. Sanitizer, rise water, etc. Can't wait to have a sink.

I bought 5 gallons of cider in Olympia on Saturday and it would be fermenting right now except my hoses are all frozen shut. I don't use hose water for the actual beverage but I do use it for the sanitizing.

 

[weatherguy]

• I've about burned my face off opening my door with a stove full of coals like that.

 

[BobUrban]

I can keep the stove at 5-600 with small splits on a pile of coals - just doesn't last more than an hour or so before I need to add fuel. If I am home I just keep adding splits until I burn it all down.

 

[mol1jb]

It does work well to add small things to a coal bed. Very small splits or my personal favorite scraps from the wood shop. Something to keep the heat up without actually adding more large fuel to the fire

 

[laynes69]

That's quite a pile of coals there. It's -2* and dropping, with windchill warnings for tonight. Currently I'm burning down the coals for loading time for bed. I'm using the softest wood I have, which is half punky elm. I just rake as many coals forward, and add a split and open the air. When things get that bad, I run my poker thru the coals to drop the ash on the bottom, then remove. If I don't and ash gets mixed in a coalbed like that, it never burns down.

 

[Dix]

• I've about burned my face off opening my door with a stove full of coals like that.

 

[tarzan]

Wow, I just thought I had trouble with coals building up.

 

[Ashful]

During the week, often in the mode of being in the house and available to tend stoves 1 hour in the morning, 1 hour after work, and 1 hour before bed. The stove gets filled with wood, run up to light the cat, and then shut down. Two full loads and one half load per day. By the time the weekend arrives, I'm usually looking at coals half way up onto the glass on my front doors, with a coal bed maybe 8" deep. It really cuts down on firebox volume. We spend much of the weekend trying to burn it back down, so we can start over on Monday. We use the trick of loading the stove just full enough that we can keep it near 500F with the air half or full open. The secret to burning down the coal bed seems to be lots of air, and we just can't do lots of air on more than 3 - 4 small/medium splits at a time.

 

[El Finko]

Same problem here. What might be the cause? I know I read somewhere that it's due to wet wood, but we can't all be burning wet stuff, right?
I know my stuff is dry, so what gives?
Didn't have this issue until the temps really dropped. Correlation?

 

[BobUrban]

correlation is the need for more heat! Loading before a complete burn cycle is finished and piling on the fuel. I am burning 15% or less MC ash and get heavy coaling in these conditions.

Solution: a better insulated home and something I need to work on.

 

[Highbeam]

correlation is the need for more heat! Loading before a complete burn cycle is finished and piling on the fuel.

I agree. A fuel load burns in cycles with a large off gas event at the beginning and then combustion of the leftover carcass at a lower temp until it turns to ash. When high output is needed, the user reloads before the carcass has turned to ash during the low/slow portion of the burn so that he can get another burst of heat.

Leftover chunks of dead wood seem to an indicator of wet wood. Eventually, my huge coal accumulation turned to white ash but it took many hours of low output.

 

[Seasoned Oak]

I have a 30 in my shop but i supplement with propane in these types of extreme tempswe are having.

 

[Ashful]

Same problem here. What might be the cause?

Solution: a better insulated home and something I need to work on.

In addition to my schedule constraints, I think this is the biggest factor. In a poorly insulated home, you can't wait for the coal bed to naturally burn down, due to rapid cooling of the house during this low heat output part of the burn cycle. So, you're throwing more wood onto a partially decimated coal bed, each cycle, and thus it builds.

In a well-insulated home, it would be possible to let the stove go until the coal bed is burned down, before tossing the next load of wood into the stove.

 

[Seasoned Oak]

In a well-insulated home, it would be possible to let the stove go until the coal bed is burned down, before tossing the next load of wood into the stove.

Exactly , the stove will get cold before the house does. ALso you could probably keep up with the heat load just on the COALS burning. Or at least maintain it.