AS owners: low roar in stove pipe?

I've been lurking around this site to answer my AS stove questions for a few years. I searched around for an answer to my present conundrum but just didn't see anything quite like this. So, this is my first posted question. Bear with me, as I'm not really sure how a forum works.

We've been running our Absolute Steel since 2016, but tonight I heard a brand-new noise. After engaging the cat and setting the damper to 2.5, stovetop temp is gradually rising to about 350 (completely normal)-- all of a sudden I hear a low, loud enough to make me nervous "roar" from the double wall stovepipe. Like, a super-strong draft noise but amplified. We get high winds here on a regular basis, just not tonight. I can pinpoint the noise as loudest at the base of the stovepipe attached to the top of the stove. But it sounds like it's making noise all along the whole pipe, generally.

In the end, I looked outside at the chimney, just in case, and there was nothing going on up there. Turned off the TV, started nervous sweating, and kept putting the damper down as the temp rose normally. I did not show the stove I was afraid. It did shoot up a bit fast, but that happens from time to time, especially with more small splits. The noise gradually disappeared with the lowering of the damper. Ended with the damper at 1, stovetop temp of 525. That's pretty standard here for very light wind. Now it's just quietly ticking, with some secondary flames and floaters.

Question: What happened, and is it something to worry about?
I'd be happy for it to never happen again.

[Note: only one thermometer here. Just the stovetop]

 

It sounds like a flue fire or an air leak but it would have to be above the fire box or your fire would be raging.

Welcome to the club, littlebeaver !

And, as Dennis said, call Woodstock tomorrow. They are great to deal with.

 

Like said above, it sounds like a glue fire or air leak down low, causing the rushing air your beard.
Welcome to the forum. Always good to see another Husker here around the fire. Where are you in Nebraska ?

 

Well, I didn't want to hear "chimney fire". I'll call Woodstock and ask about this. Of your suggestions, I'm wondering about a leak where the pipe meets the stove. Our stovepipe could be better, and the base looked a little sad and worn when I cleaned it this fall. It will be warm in a couple of days and I'll take it apart for a look.

I'm running the stove again this morning with no noises or issues. We had the chimney and pipe cleaned in early October with no creosote and just some light soot buildup (from all of last winter). Of course, I don't know what it looks like now, but if anything I would have guessed I'm running the stove more effectively than last year. So a creosote issue would be really depressing, and something to figure out. The only evidence I have against a flue fire idea is that while the stovepipe was hot, I could easily touch it with my hand.

**Story: We did have a fire in the stovepipe in 2018, but it was a fluke of the weather. I started a cold morning fire just as an ice storm started. The wind was blowing ice horizontally and completely coated the mesh on the chimney cap as smoke was just starting to come out. Black ice goo. The fire was in the horizontal portion of the stovepipe inside the house and was so hot that it burned the paint off the exterior of the pipe. It stopped relatively quickly once I shut the draft down. Took a while before I wanted to burn again, though.

Thank you for your help, and welcome!

 

We're in south Gage County. Near Rockford Lake.

 

Update:
Pretty sure it was a small flue fire.

I have burned a few times since the ominous noise. No issues. But I also called Woodstock today and they suggest disassembling the pipe and looking everything over, and sending them pictures. So that's what will happen when it's cooled off. Thank goodness it will be warm for a few days. I had not thought of having backup pipe, that's probably a good idea in case this is shot.

Any opinions about single vs. double-wall pipe for replacement (if needed)? The double-wall we have is a little tedious to take apart and put together, in my opinon. And now I know the value of a flue thermometer!

Honestly, I'm a little mystified. The performance of the stove has been good this year. We do need to replace the combuster (backorderd), but maybe it's the wood? I can get out there with a tester-- it's all about 2 years stacked. A mix of different species this year: hackberry, mulberry, hedge, red elm, and eastern red cedar. I know most people don't burn cedar-- it's worked for us in the past, and is invasive around here, so we're regularly cutting trees down. I bet the firebox would be cleaner without it...

 

No worries here on burning correctly dried Cedar. Any chance your not quite seasoned enough? Sounds like some of your wood varieties would be hard pressed to be correctly seasoned for me in your "about 2 years".
Worth warming up a handful of splits to room temp and re-splitting them for a moisture meter check on the freshly exposed inner face? Believe I would.
If your going to update your connector pipe look into double wall. Anything to keep your exhaust temps up so you aren't creating as much creo. Good luck.

 

Thanks for the advice. I'm going to test the wood today and take measurements for the pipe in case needs replaced or reconfigured. Taking the pipe down tonight to assess and then probably just do whatever the stove company tells me to do.

Most of the wood we burn is cut as standing dead or downed trees. So there is a small amount of drying already taking place. From that point, it's one year stacked outside and then one year in a wood shed. The hedge and mulberry certainly take a long time to dry from green, but most of the hedge we cut is very long dead. at least a decade. The mulberry on the other hand we cut green. That might be the issue. I wasn't aware that a moisture meter would read differently at room temp, though. Will have to try it both inside and out.

All said, I'm a very experienced worrier and a relatively inexperienced burner. I thought this year would be when I found my "chill" about the stove...

 

Nothing wrong with exercising a high level of safety/caution around fire. Mostly when it's in a box in your home!

Most moisture meters are calibrated to be accurate around the 70 deg mark. Letting your selection of splits get to room temp makes a difference in accuracy. The splits still must be re-split and tested on the freshly exposed inner face. This is the part most folks have trouble understanding. Testing the outside of a split means next to zero. Let us know what you find out.

Now all I can think about is burning "long dead Hedge". Good stuff.

 

So, if fresh splits were tested outside and the temperature was 55 degrees....will the reading be high or low?

 

Well, heat adds resistance...and water in wood lowers resistance...so I'm guessing that wood below 70*F would read wetter than it is? (no idea how much)

 

Updates for those interested:

Wood moisture:
Mulberry tested at 35 percent. Which is a lesson on not being so presumptuous. So, it will sit for another year and we'll get some oak from a neighbor. Everything else was under 20 percent, most was under 15. Even if this turns out to not be the reason for the noise, I'm glad to have tested everything and have a clearer picture..

As for the roaring noise and the stove pipe, we are coming to a new conclusion. After disassembling the stove pipe, looking over the stove and combuster, and answering Woodstock's questions, the reason for the noise is actually still not clear. The stove pipe configuration is less than ideal, and we'll be making changes to it to reduce build up at a certain corner, but it does NOT seem to be a pipe fire that was making the noise, as there wasn't any actual creosote or much ash in the pipe itself and no evidence that kind of heat in the pipe. I reassembled the pipe and ran a few more days of fire, all without incident until a few days ago when the noise happened again. Except that this time I noticed a few things:

1. The noise began at the same temperature as last time (350), and
2. only after the bypass was closed and the temperature had started to rise from the combuster activity.
3. The noise perpetuated longer, even though I closed the damper down to 1 within a few minutes this time. It did decrease in volume though.
4. The noise is not actually coming from the base of the stove pipe, but rather the top cavity of the stove. (This took a few different ears to figure out.)
5. Our combustor does have a crack horizontally splitting it and is a little loose in the frame on one side.
6. There is a hairline crack at one corner of the bypass opening. Woodstock is assessing this, but I don't think it is related to the noise.

I knew about the damaged combuster earlier this summer and ordered one, but they have been back-ordered since that time and there is really no telling when they'll be available. It has still been getting up to 550 consistently each fire, so, it's not a dead combuster. But there is a 1/8th inch gap between the combuster frame and the "waffle" interior on the side that is most loose from the crack, and I'll be asking them if this could cause such a noise-- and if it's going to cause damage to anything else.

 

So...if you test fresh splits outside at around 55 degrees, and they test under 20%, they should definitely be good to go?? They're forecasting almost 70 degrees here for this Friday, so if I think about it I may do a lil 'speriment.....

littlebeaver, when you tested your wood, did you do the 70 degree thing? Did you test at non 70 degree to see the difference? Just curious....

 

Very interesting update....
I get a little bit of some sound every so often. Cross a whoosh with a rumble, but low and pretty quiet/muted, and that would be how I'd explain it.
I'm curious to know how this shakes out for you.

 

Testing cold splits will give unrealistic low M/C readings.

Species Correction Table (delmhorst.com)

 

Ok, so if the wood is warm, it may read a higher MC, compared to when/if it were cold(er). So my pieces (testing a fresh split face) that were under 20% at 55 degrees, could (may) be over 20% at 70 degrees...?

If I'm understanding correctly...the MC doesn't really change (assuming the wood changes temperature for testing in a "relatively short timeframe"...hours or day or so, not long time that could lead to more drying). The temperature of the wood just affects the accuracy of the tester.....correct?

 

Sort of? I tested when it was 50ish degrees and the readings were "sporadic" with the mulberry. One piece would test at 18, the next at 35. Variability is normal I suppose, especially with trees that have awkward splits and a lot of branching. I tried to test a few extra large splits, too. But when I brought the wood inside for a day, then split it for testing, it all rounded out to 32-33. No more low readings from any of the wood.

I'd be interested in more "scientific" experimentation with all the wood we cut, both green and long-dead downed trees, at different temps.

 

That sound description is *exactly* what I'm talking about. I would describe it as about as loud as a box fan. It's possible I didn't notice it last year if it was a lower volume.