My NC 30 scared me the other night

[4ward]

I've been running this thing for about a month solid now. Wow, do I love it. It has slowed the remodel of my new home considerably. I find myself just sitting there watching the flames dance in mid air. Anyhow, I've been learning how to run this thing and have been playing with where to set the air control given the STT's and size of load. I've gotten it down decently, still got a long way to go though. My wood isn't the best, but it's not horrible either. I dropped some ash trees that have been dead for a couple years and split them up in Dec. It's what I've got for now.

My issue- As per what I've been doing, when this thing starts to go out of control (nuclearish) I'll shut the air all the way down until the flames completely die out. I'll give it a little bit and then pull the lever back out about a 1/4" or so. Usually it'll take a few minutes and the flames will come back and all is right with the world and I can go on about getting work done (or sitting and staring at the awesomeness that's happening behind the glass). This time though, ungoodness happened. I shut it down, let the flames die, opened it back up some and walked to the kitchen to get a drink. As I look back at the stove, it basically exploded inside the firebox when the flames relit. It shot with enough force to blow smoke out and I think a little bit of flame out the connection to the stove pipe. It also blew out the flame. I started heading toward the stove to shut it down and it did it again. It didn't blow the flame out this time though, so I let it go and it was fine after that. I watched it like a hawk after that until I knew it was on the downswing of the burn. STT was right at 750, measured on the angle, directly in front of the connection, no ridiculously loud overgrown hairdryer on. Outside it was high 20's, can't remember if it was windy or not out.

Thoughts, suggestions?

 

[jatoxico]

Your stove was huffing, excess gases coming off that accumulate and eventually go off at once instead of burning a little at a time. Not real dangerous to the stove but could knock a poorly fitted/secured pipe loose so not desirable.

Instead of shutting air down all the way and starving it of air bring it down slow in stages. Sounds like you may need to do that starting earlier than you are doing now to keep temps in control.

 

[mol1jb]

Ya back with I had a NC 30 in the basement of my old house it did that from time to time when I cut the air back too quick. Scared the poo out of the dog.

 

[Highbeam]

Don't chop the air so fast. I go to 75% pretty quickly, and then down to my high output cruise setting as soon as I can do it without snuffing the flame.

You should always have flame in the box until you are down to coals.

 

[saskwoodburner]

Not the first person to find out about this particular event. My stove is the only other thing besides the dogs that goes "Woof!" too when I've stalled a fire.

 

[iamlucky13]

It seems to me that it's best to err on the side of generous with the air. If you were getting gases accumulating inside the stove waiting to flash as soon as they had enough air, you were probably also sending quite a bit of partial combustion products up the chimney that can form creosote or at least excess smoke. In fact, next time you try to stall the fire like that, you might go outside and see what your exhaust looks like. I'll bet it's a bit smoky.

By going outside from time to time to check my chimney, I've gotten a sense of how much I think I should close the air down the air based on what the flames are doing and what that usually looks like smoke-wise. When the flames get just noticeably less vigorous than full open, I let the stove run like that for ~10 minutes, then try a closing it down a bit more.

To avoid overheating the stove, my strategy is to use smaller loads, rake the coals forward and load the wood as far to the back as possible, use larger splits, or let the coals burn down more before reloading. And if the temps get towards the high end, turning on the loud hairdryer is first thing I'd do to help keep them in range.

That's just my own trial and error. I'm happy to be advised otherwise if there's better strategies.

 

[CenterTree]

4ward: Very interesting to see your thread. I was going to start a thread about this also as the EXACT same thing happened to me just last week.

I had a full secondary going and closed the air completely. Put the fan on and went up stairs to answer the phone. Came back down a few minutes later and the fire box was "flameless".

I pulled the primary knob out a bit and waited for flames to reappear. Well, I got the same "HOLY CRAP" moment your got.

POOF! Smoke out the pipe seams. Not a relaxing moment.

Thanks for saving me a new thread....LOL.

 

[BrotherBart]

106% of the time that first "secondary burn" isn't. It is the charring burn part of the cycle where bark and the surface of the wood is charring. If you shut the primary air all the way down that the fire is going out every time as soon as the charring is over. Usually twenty minutes or so with my loads.

Give that puppy some primary air so those gases the charring burning cooks out of the splits has something to keep them burning.

 

[BrotherBart]

Come to think of it, years ago the charring burn used to be a regular part of any conversation about the burn cycle on this forum. I don't remember it even being mentioned in years now.

 

[Sprinter]

Also known as backpuff. Happened to us (once) early in our first year. It's often part of the learning process with any stove. Scary, but it won't happen again, now that you are aware. All the above posts are good advice. Just tend the stove carefully and turn the air down in stages. It may be a little more critical with a large box stove like yours, especially with the stove full.

 

[4ward]

I've seen mention of the charring stage in my research. This happened appx. an hour after reload, so that may or may not be part of it. I'll usually run full open after reload for 10-15 mins and then bring the air control in to appx 3/4" out from the ashlip. I'll let it get up in the 600* range like this and then put the air control somewhere roughly even with the ashlip. "Usually", that works and it runs in the 7-750 range for quite a while and the STT doesn't climb rapidly. When it does climb quicker than I want, I'll take it in to 1/4" out from completely closed. The few times that doesn't work is when I completely shut it down. Sometimes I use the fan to cool it down, but I really dislike that thing. I'm also trying to learn how to run the stove, which is another reason I try to not use the fan. I'll be putting a squirrel cage fan on it soon.

I run this sucker hot as it's the only source of heat I want to use for now. There's a couple electric baseboard heaters that I refuse to turn back on as they cost me over $200 to keep the house at 55 for a month. I can't even imagine what it would be keeping the house in the high 60's. There's passive solar heat that the previous owner removed all the sensors, tank, and pump before he let himself get booted out of the house. Hoping to get that up and running before next winter. I'm also going to tie into the duct work for the solar to use the heat from the stove also. So many projects.......

 

[CenterTree]

Don't be afraid to use that fan if you need to bring your STT down. The fan will allow you to keep your air open a little bit while also maintaining a desirable temp.

I vary the use of my fan from load to load. It seems it depends on the wood type a lot.