22% Moisture content firewood

[vtmattyb]

Hi!

I am new to the forums and to wood burning generally. My family recently moved to Vermont and our house has a Hearthstone Mansfield stove in the living room (which was definitely part of the appeal!).

Being new to serious firewood use, I have a bit of a dumb question that I can't seem to find directly answered anywhere. I have done quite a bit of reading on the forums here as well as other places around the internet about seasoning firewood. The consensus is clearly that 20% or below is ideal in terms of moisture content for firewood.

Our house came with about a cord of wood; I have no real information about the wood beyond that (how long it has been seasoning, type of wood, etc.). I have purchased a moisture meter and have split and checked the middle of a variety of the pieces in the stack; I consistently get moisture reading between 20 and 22.5% depending on the specific piece being tested.

My question is: given that moisture meters are far from 100% accurate, how seriously should I take the 20% level as a "hard" line above which I shouldn't be burning my wood? Is something at 22% "close enough" and thus fine to burn this winter, or is that asking for trouble? I don't yet feel particularly confident with some of the other methods like the noise two pieces make when banged together.

For context, I have three young children and safety is my primary concern. The last thing I want to do is burn a bunch of wood that isn't ready and end up with a chimney fire on my hands from creosote buildup.

 

[begreen]

The wood sounds like it is burnable, but some of it may not be ideally seasoned. You can mix it with known, dry wood to help it burn better. If it is kept top-covered it should continue to lose moisture over the winter. As long as you are not seeing smoke from the chimney it should be burning hot enough. Put a flue thermometer on the stove pipe to know how much heat is going up the pipe and clean more frequently until you know how the wood is burning. Maybe once a month?

 

[tadmaz]

Try out a fire and see if you can see water coming out of the end of a split or hear hissing.

 

[ChrisRoss]

I think the wood is not properly seasoned yet. Check if it is burnable now. If not, wait a bit.

 

[vtmattyb]

To quickly recap and make sure I’m on the right track: it sounds like I should try burning a bit of the wood and seeing if I get sizzling/hissing and moisture on the ends (in which case it is not ready). Assuming I don’t, and I have no smoke coming out do the chimney/good flue thermometer temps I should be good to burn?

In any case, I will try to mix this wood with wood that is known to be totally dry and ready to go. Which leads me to one other question: is the key metric here the average MC of ALL of the wood in the firebox (so if I have an equal sized piece of 15% and 25% MC wood we’d average to about 20%), or should I really be thinking on a per-piece basis (no individual pieces over 20%)? I suspect it is the latter.

Sorry for being slightly in the weeds on this stuff, but it’s really helpful as I start to learn what I’m doing!

 

[Firewood Bandit]

When you are taking a reading, are you splitting a piece to get an internal reading or from the end?

This is unclear:
I have purchased a moisture meter and have split and checked the middle of a variety of the pieces in the stack; I consistently get moisture reading between 20 and 22.5% depending on the specific piece being tested.

 

[Grizzerbear]

Some will say piece by piece...others will say it will average it out. I have found that mixing your known dry wood with some of your less seasoned will help u establish a decent burn while they work to lower moisture of the wet pieces. So to me it is a piece by piece. Relax though....you are in a way better position than most their first year.....even if all your wood was at say upper twenties. Most people still assume u can cut split and burn immediately as the old ways lol. And as far as the chimney and fires.....keep your flue temps up and inspect/clean it every month until you get idea of what is happening up there. Its easy, takes about twenty minutes if not less and well....why not. I will say u will need to scrounge pallets, bio bricks or lumber scraps because a cord is not going to last you the winter if u intend to burn all winter. Hope you enjoy the stove and remember as I'm sure u have read on here...get ahead on wood supply by two years. The benefits are amazing. Good luck.

 

[vtmattyb]

When you are taking a reading, are you splitting a piece to get an internal reading or from the end?

This is unclear:
I have purchased a moisture meter and have split and checked the middle of a variety of the pieces in the stack; I consistently get moisture reading between 20 and 22.5% depending on the specific piece being tested.

I am splitting the piece to get an internal reading; meaning I am measuring in what used to be the exact middle of the piece (not the ends) before I split it for testing.
Thanks!

 

[vtmattyb]

Some will say piece by piece...others will say it will average it out. I have found that mixing your known dry wood with some of your less seasoned will help u establish a decent burn while they work to lower moisture of the wet pieces. So to me it is a piece by piece. Relax though....you are in a way better position than most their first year.....even if all your wood was at say upper twenties. Most people still assume u can cut split and burn immediately as the old ways lol. And as far as the chimney and fires.....keep your flue temps up and inspect/clean it every month until you get idea of what is happening up there. Its easy, takes about twenty minutes if not less and well....why not. I will say u will need to scrounge pallets, bio bricks or lumber scraps because a cord is not going to last you the winter if u intend to burn all winter. Hope you enjoy the stove and remember as I'm sure u have read on here...get ahead on wood supply by two years. The benefits are amazing. Good luck.

Awesome - I appreciate the great info!

I have a second cord that's coming that should be seasoned (I know - buyer beware, but I'm buying it from the people who do various yard work and maintenance for us so they have an incentive to keep the relationship strong). I also have a bunch of other standing dead stuff that I cut in the last few months and should be burnable this winer judging by the MC readings I'm getting. Thankfully we are using the firewood as our secondary source of heat this winter, so if we run short it's not like we will in dire straights.

Now to get out and put some firewood away for next year and beyond!

 

[spudman99]

Heat is used to boil the water out of the wood. If the insert is filled with 22% logs, heat will be used internally first to drive the moisture out. That results in less heat for the firebox output. Purpose of mixing dry lumber is to raise the internal temperature to yield effective heat while minimizing water evaporation. Performance suffers but you still get heat.

So long as you are not burning significant quantities of higher moisture wood, you should be ok. Take a look at the chimney exhaust after the fire is established. If it is clear then that is a good sign. Also plan now to perhaps clean the liner several times this winter in an abundance of caution. That should give you piece of mind for the kiddos.

 

[Woody Stover]

I don't yet feel particularly confident with some of the other methods like the noise two pieces make when banged together.

I haven't found that method to be particularly reliable; Some wood will sound like it is "ringing like a bell" when you knock splits together, but will still be pretty wet. OTOH if you hear a dull thud you can be pretty sure it's wet.

is the key metric here the average MC of ALL of the wood in the firebox (so if I have an equal sized piece of 15% and 25% MC wood we’d average to about 20%), or should I really be thinking on a per-piece basis (no individual pieces over 20%)?

Problem is, not all of the wet and dry wood in the box will be burning at the same time. If it's mostly wet stuff burning at a particular point in time, it's gonna be a problem.

I'm buying it from the people who do various yard work and maintenance for us so they have an incentive to keep the relationship strong). I also have a bunch of other standing dead stuff that I cut in the last few months and should be burnable this winer judging by the MC readings I'm getting.

Those folks may mean well, but how much do they really know about what is dry wood? Your best bet, if you have a woodlot to work, is finding small trees <8" with most or all the bark fallen off. Test as you cut it, but most should be pretty dry, even some of the Oak.
Can you describe your chimney setup? Is there Class A chimney from the ceiling on out, or an insulated liner to the top if it is vented into a masonry fireplace? If you have connector pipe part way, then it dumps into a clay tile masonry chimney liner, a lot more condensation will take place, as the clay liner will cool the flue gasses much faster than an insulated stainless liner will.

 

[vtmattyb]

So long as you are not burning significant quantities of higher moisture wood, you should be ok. Take a look at the chimney exhaust after the fire is established. If it is clear then that is a good sign. Also plan now to perhaps clean the liner several times this winter in an abundance of caution. That should give you piece of mind for the kiddos.

I'll definitely keep an eye on the chimney exhaust.

I did have the stove and our fireplaces inspected a few weeks back by a chimney sweep. He said that everything looked good right now and it didn't need a cleaning before the burning season starts. I told him we'd likely use the Hearthstone 4-5x per week; he replied that if we are burning less than about three cords of wood this winter (we will definitely fall bellow that; I would guess north of one but south of two) we should have no issues and to just have him out in Spring for a cleaning. Does that pass the sniff test to you guys?

 

[vtmattyb]

I haven't found that method to be particularly reliable; Some wood will sound like it is "ringing like a bell" when you knock splits together, but will still be pretty wet. OTOH if you hear a dull thud you can be pretty sure it's wet.

That's good to know. I won't put too much stock in that method generally. Plus now I don't have to explain to my wife why she's looking out the window and seeing me banging firewood together like a cave man!

Those folks may mean well, but how much do they really know about what is dry wood? Your best bet, if you have a woodlot to work, is finding small trees <8" with most or all the bark fallen off. Test as you cut it, but most should be pretty dry, even some of the Oak.
Can you describe your chimney setup? Is there Class A chimney from the ceiling on out, or an insulated liner to the top if it is vented into a masonry fireplace? If you have connector pipe part way, then it dumps into a clay tile masonry chimney liner, a lot more condensation will take place, as the clay liner will cool the flue gasses much faster than an insulated stainless liner will.

I do have a small bit of wood on our property - probably about 3 acres of forested land. There doesn't seem to be a whole lot of standing dead stuff unfortunately. Most everything seems to be alive or to have been rotting on the ground for many, many years. I'll keeping looking though; I've found some ok wood this way so far.

In terms of the chimney, forgive me in advance because I'll probably butcher some of terminology and/or be unclear. The Hearthstone has a connector pipe that exits from the top of the stove. The connector pipe is single walled; it exits the stove vertically and then takes an almost 90 degree turn and enters our masonry chimney through a hole/thimble. The masonry chimney is pretty tall. The stove is on the first floor and the chimney probably stops ten feet above our second story roof.

My understanding is that I could clean/inspect the connector pipe myself, but it sounds like the chimney is the real potential issue. From doing some light reading (certainly not exhaustive), it looks like the chimney needs to be cleaned form the top down (i.e. standing on the roof) which is not an option for me unfortunately - the chimney is very high in the air and sits in the middle of our very steep metal roof. Even the chimney sweep said he was dreading going up there!

 

[Woody Stover]

There doesn't seem to be a whole lot of standing dead stuff unfortunately. Most everything seems to be alive or to have been rotting on the ground for many, many years. I'll keeping looking though; I've found some ok wood this way so far.

Some types of wood on the ground will hold up better than others. The sapwood may be rotted but the heartwood may still be good. You might find some good Cherry trunks or Oak branches..

connector pipe is single walled; it exits the stove vertically and then takes an almost 90 degree turn and enters our masonry chimney through a hole/thimble. The masonry chimney is pretty tall. The stove is on the first floor and the chimney probably stops ten feet above our second story roof...My understanding is that I could clean/inspect the connector pipe myself, but it sounds like the chimney is the real potential issue.

I'm not real familiar with how that type of setup is done, but if a liner or something runs to the top after the thimble, that will stay hotter and cleaner than a tall masonry/clay liner will. Connector pipe down low should stay plenty hot.
I hear ya, those metal roofs are scary..my BIL has one that's not steep but is still treacherous with any kind of dew, etc. A steep one would be bad even if dry, I imagine.

 

[Grizzerbear]

the chimney is very high in the air and sits in the middle of our very steep metal roof.

My setup is similar with steep metal roof. I clean mine from bottom but if u ever have to get up there on your roof.....cut some cushions out of some old office chairs and duck tape to soles of your shoes. Old roofing trick I learned from a Mexican guy doing iron work. U will feel like a idiot but it works.

 

[MrWhoopee]

I too have a metal roof. I've worked on the stovepipe twice from the top. That prompted me to figure out how to clean it from the inside. If your installation doesn't already have a flexible liner to the top of the chimney, plan on having one installed. It will improve the draw, reduce the accumulation of creosote and potentially make it possible to clean from inside the house with a Soot Eater.

 

[kborndale]

Awesome - I appreciate the great info!

I have a second cord that's coming that should be seasoned (I know - buyer beware, but I'm buying it from the people who do various yard work and maintenance for us so they have an incentive to keep the relationship strong). I also have a bunch of other standing dead stuff that I cut in the last few months and should be burnable this winer judging by the MC readings I'm getting. Thankfully we are using the firewood as our secondary source of heat this winter, so if we run short it's not like we will in dire straights.

Now to get out and put some firewood away for next year and beyond!

Dont expect the second cord to be below 20% moisture. Its not that the dealer is trying to rip you off, its just that it really is not practical for a wood dealer to have wood that is dried below 20%. Think of how much room a dealer that sells dozens of cords a year would need to stack all that wood for a year or two before they sell it. Takes a lot less room to have a big pile of wood, but only the wood on top of the pile is really exposed to the sun/wind and drying. Seasoned to a dealer is sitting in a pile for a season. That second cord will most likely be burnable next year, and ideal the year after.

 

[spudman99]

Just to echo @kborndale above, I often see the large firewood sellers have pretty high stacks of split wood in June or July in my area. It was typically cut in winter or spring. By August it is all gone, so at best 3 months of open and uncovered piles (some are 30' high). They call it seasoned (meaning the spring season or 3 months.... hehe).

Remember that burning wood for heat and not ambience is a job, one that most of those here on the site love. Thus plan accordingly, make the time or effort to get the wood cut, split and stacked (CSS). You clearly seem motivated and interested. Hang around, read and ask questions herein. You will find many folks willing to help you, even with the most basic question.

 

[kennyp2339]

The second cord is a good thing, if anything split a few pieces that are room temp and test with the meter to get a base of overall moisture content, if it's 25%+ then you'll be able to take an average size piece of the new wood and compare the weight feeling to your current stuff, you'll start getting the feel for when grabbing a piece and knowing that it isn't ready yet.

 

[Marshy]

My experience is 20-22% moisture is fine to burn with no deposits forming and no concerns. Your experience may differ.

 

[gzecc]

Use the meter as a reference tool. Test your palm, you should get mid 30s. Test some wood that you suspect is not seasoned, test some that you think is seasoned. test some you know is seasoned. Eventually you will be very knowledgeable about wood seasoning in your yard.