How much wood "hissing" is tolerable? How bad is it for the chimney???

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Swedishchef

Swedishchef

Minister of Fire
Jan 17, 2010
3,275
Inuvik, Northwest Territories
Hi guys

I have been burning some maple lately. The odd piece hisses for about 10 minutes max. Normally on the lowest part of the wood, a white foam appears. I keep the fire roaring while it is doing this and once it stops, I turn down the primary and let the secondaries take over.

I am hoping that the hot flue temps are preventing condensation in the chimney. How bad could it be?

I have not burned wood like this the entire winter. it has only been of late.

Thanks
Andrew
 
Burn it baby. just throw a 2 by 4 in there to help heat it up faster.
 
Your wood is hissing and foaming at the mouth? Welcome to the unseasoned wood club. Keep an eye on the pipe leading to the chimney. Thats where I see most of the creosote buildup.
 
Tolerable to me is a minute or less hiss when a split lands on a hot bed. Foaming is definitely NOT tolerable. You need drier wood or you're going to goo up your pipe and chimney in short order.
 
I figured there would be 2 schools of thought: add some wood to help drive out the moisture and the other to get rid of it. The funny thing is that it is maple that has been c/s/s/ for over 3 years now.

I think the foaming is simply t he nature of the moisture: it's from maple..aka maple sugar? Like I said, after 5-10 minutes (from a COLD start) it is gone.

Andrew
 
My goal is totally dry wood. It's been successful for several years now and shows in a clean chimney so I'm not changing it.
 
Another interesting point: within the wood that hisses (like I said it's only a few pieces), all the other wood is fine. I have a mixture of yellow birch and maple. Same size splits: NONE of the yellow birch hiss and SOME of the maple does. I am thinking it's the off gassing/boiling of the sugar inside the wood (???).

Andrew
 
A good thing to test: Take a split and re-split. Test Moisture Content on the inside side. I've burned ~1 cord of Silver Maple this season. It has been CSS for only 1 year. (We do have many 90+* summer days and bright sun here, tho). My MC is 15-17%. If you have Sugar Maple - may behave differently.
 
If this wood has been drying for three years I wouldn't expect to see this kind of moisture present...type of wood shouldn't make a difference. Could some splits be slightly punky...from dead branches maybe? If so, they might absorb a bit of water if rain hits the end of the splits. The fact that only a few of the splits are wet, not all of them, points to something like this happening. So does the fact that the splits stop hissing fairly quickly.
You could try letting this Maple dry out by the stove for a week or two and see if the problem goes away. It doesn't sound like you'll get a lot of gunk in the flue from the occasional hisser, but I would keep an eye on it nonetheless.
 
Some of my pine does this... It's bone dry. Usually I see sap start oozing out if I watch carefully enough. It tends to be on splits where a limb was cut off.
 
Maybe this discussion is best kept exclusive of softwood. Pine resin may still have some moisture content, but it's so oil laden that it will easily burn.
 
I get it with birch as well.

Hass said:
Some of my pine does this... It's bone dry. Usually I see sap start oozing out if I watch carefully enough. It tends to be on splits where a limb was cut off.
Click to expand...
 
start work on on next winters wood and you will not have hissing wood.
i have yet to have one piece hiss this year, as i have wood that is stacked and dry for 1.5 seasons after learning how much of a PITA it is to burn wet wood...
 
Swedishchef said:
I figured there would be 2 schools of thought: add some wood to help drive out the moisture and the other to get rid of it. The funny thing is that it is maple that has been c/s/s/ for over 3 years now.

I think the foaming is simply t he nature of the moisture: it's from maple..aka maple sugar? Like I said, after 5-10 minutes (from a COLD start) it is gone.

Andrew
Click to expand...

I have maple that does the same thing and that wood seems dead bone dry but still hisses, my thought was the sugar or sap in the wood boiling out, only lasted a few minutes and burned like a gas soaked rag. Shawn
 
Swedishchef said:
Another interesting point: within the wood that hisses (like I said it's only a few pieces), all the other wood is fine. I have a mixture of yellow birch and maple. Same size splits: NONE of the yellow birch hiss and SOME of the maple does. I am thinking it's the off gassing/boiling of the sugar inside the wood (???).

Andrew
Click to expand...

Most unlikely, for many reasons.

One of the first things that happens within fresh splits is the fermentation of plant nutrients. Don't believe me? Sometime when fresh sugar maple splits are stacked inside a shed, close the door for a bit, then step inside. Ever been to a winery?

Try over-cooking some sugar on the stove sometime, for grins. No hissing, plenty of really yucky black poo, etc. (Make sure wife is out-of-area.)
 
Fifty pounds of wood dried to 15 or 20% moisture content - in other words, very dry wood - still contains 7 to 10 pounds of water. This still has to boil off, so some sizzle is inevitable. I'm not sure that wood with 0% moisture content would be anything more than powder.
 
If your getting good/normal stove top temps that's a good sign, if not, more cause for concern. I would check/clean any connecting pipe and chimney maybe a month into burning and see how it looks; that will give you the real answer.

Jim
 
Thanks for the replies guys.

I am glad that I am not the only one who gets this problem. Like I said, the wood is 3 years old. That's why I have a hard time believing it's still wet.

I already have wood that is 2 years old for next winter. Buy then it will be 3 years old. In fact, I have wood already c/s/s for the next 3 winters.

CTYank: I understand what you're saying about burning sugar on a stove. But something tells me that what is boiling out is sugar with moisture (small amounts). The bubbles that come out are like foam, not water. I have tried burning green wood in the past in firepits, etc. I know what wet/hissing wood is like.

I agree with SHawnG: it burns like a gas soaked rag after the hissing is done.

For example, I just lit a cold stove start. I put a piece of maple inside. I will try and see if it happens and if it goes, take a picture. I still think it has to do with the sap: rock maple is one of the only hardwoods that you actually TAP INTO to get a liquid to come out... drop by drop into a line or intoa bucket.

Another thing I just noticed: the moisture is coming out ONLY on the bottom of the piece of wood, nowhere's else. Yet flames are burning all around it. Hrm....

Andrew
 
Swedishchef said:
something tells me that what is boiling out is sugar with moisture (small amounts). The bubbles that come out are like foam, not water.
Another thing I just noticed: the moisture is coming out ONLY on the bottom of the piece of wood, nowhere's else. Yet flames are burning all around it.
Click to expand...
I've seen the foaming on non-Maple species as well...
The bottom of the wood is where the most coals are, and the most heat. That's where any moisture will first be seen, and where you'll see the most moisture. I think moisture in the wood is pulled toward the driest (hottest) area...
 
Swedishchef said:
Thanks for the replies guys.

I am glad that I am not the only one who gets this problem. Like I said, the wood is 3 years old. That's why I have a hard time believing it's still wet.

I already have wood that is 2 years old for next winter. Buy then it will be 3 years old. In fact, I have wood already c/s/s for the next 3 winters.

CTYank: I understand what you're saying about burning sugar on a stove. But something tells me that what is boiling out is sugar with moisture (small amounts). The bubbles that come out are like foam, not water. I have tried burning green wood in the past in firepits, etc. I know what wet/hissing wood is like.

I agree with SHawnG: it burns like a gas soaked rag after the hissing is done.

For example, I just lit a cold stove start. I put a piece of maple inside. I will try and see if it happens and if it goes, take a picture. I still think it has to do with the sap: rock maple is one of the only hardwoods that you actually TAP INTO to get a liquid to come out... drop by drop into a line or intoa bucket.

Another thing I just noticed: the moisture is coming out ONLY on the bottom of the piece of wood, nowhere's else. Yet flames are burning all around it. Hrm....

Andrew
Click to expand...

All I have burned for many years is maple, yellow birch and some apple, beech. It is my experience that when you have hissing and foaming on any wood, that wood is wet. "Sugar" or hardrock maple is my predominant wood burned and is c/s/s for 12-14 months prior to burning, very rarely do I get "hissing and foaming" from it. It goes into the stove at indicated 10-20% mc on my moisture meter.

High "sap" content indicates high water content. I'm surrounded by maple sugar camps and get the majority of my wood from these camps. Maple which has been been harvested from the higher dryer hillsides is much better than that cut from low country and which, when cut, often I find the heartwood has deteriorated to basically a hollow tree. Nothing scientific here, just general information gathered by myself and my sugar camp owning friends.
 
Swedishchef said:
Thanks for the replies guys.

I am glad that I am not the only one who gets this problem. Like I said, the wood is 3 years old. That's why I have a hard time believing it's still wet.

I already have wood that is 2 years old for next winter. Buy then it will be 3 years old. In fact, I have wood already c/s/s for the next 3 winters.

CTYank: I understand what you're saying about burning sugar on a stove. But something tells me that what is boiling out is sugar with moisture (small amounts). The bubbles that come out are like foam, not water. I have tried burning green wood in the past in firepits, etc. I know what wet/hissing wood is like.

I agree with SHawnG: it burns like a gas soaked rag after the hissing is done.

For example, I just lit a cold stove start. I put a piece of maple inside. I will try and see if it happens and if it goes, take a picture. I still think it has to do with the sap: rock maple is one of the only hardwoods that you actually TAP INTO to get a liquid to come out... drop by drop into a line or intoa bucket.

Another thing I just noticed: the moisture is coming out ONLY on the bottom of the piece of wood, nowhere's else. Yet flames are burning all around it. Hrm....

Andrew
Click to expand...
I've had problems with norway maple taking forever to dry. If its a large piece, they really hold on to the moisture.
 
hissing mean the boiling water is coming out as steam
wood is not dry

thats what ECO BRICKS are for!!!!
 
I didn't see anyone ask if the wood is covered or uncovered. Could it be a few top pieces got a little rain/snow on them and it's just surface moisture?
 
I wouldn't worry about it too bad . . . but I am thinking this wood is not as prime as it could or should be.
 
I totally understand why everyone is saying that the wood is simply NOT dry. But how the ^#%$ can it not be? Open sun and wind for 3 summers, it was c/s/s during that time AND it is in my greenhouse which acts as a KILN. The wood has that hollow/dry sound when knocking, has turned colors to a greyish tint and seems darn dry to me. I guess the center it still damp then.

Hardrockmaple: you only dry yours for 14 months?!?!?! Mine has been sitting in sun/wind for almost 3 years...that is why I am having a hard time with it "being wet".

It is not surface moisture, I can see it coming out of the edge of the wood. My stove top temps still reach 700 and my flu temps 400-500.

I think I will blame it on aliens or wood gremlins. Because I am not willing to accept that I need to dry my damn wood for 4 years before burning it! lol.

And unfortunately, I don't think it's simply surface moisture. I will get a picture of a piece todya or tomorrow and post it for viewing.

I still think it's something of a water/unknown mixture. In a stove the temps should hit 800+ degrees F easily within the beginning of the burn. This "stuff" is like a foam or bubbles and can actually DRIP down the edge of the wood for 5 minutes or so. At 800F, all moisture would evaporate instantaneously and would not have time to froth and drip....or would it?

Andrew
 
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