Heat Spikes in My Wood Stove

[soupy1957]

To carry on from a previous Thread I started, but to focus more on the "high temp" issue:

There are two times in the burn cycle that I see as the highest temps being generated......
1) When re-loading the wood stove during the day time as needed for heat (multiple times per day)
2) When re-loading prior to bedtime (one load that needs to burn thru most of the night.

With regard to the first one, we wouldn't typically let the fire burn down to a smoulder, but keep a constant burn going. The temps WILL by nature jump, when the new splits are added, (typically a couple at a time anyway), and yet in MY particular case, I have found that if I try to achieve a Secondary Burn by closing down the Damper, it cuts out too much of the air and the fire doesn't seem to want to burn well. So I never really shut down the Damper much more than half, at most.

With regard to the second one, I've not mastered this yet, but I assume that I will, this year, since it will be our first 24/7 burning season. I see myself putting about 3 splits on the fire at about 10 PM, and then waking up to take a whiz at about 3 AM, and adding more.

In each case of re-stocking the fire, the temps are naturally gonna spike, and then burn down. Aren't we all really saying that it is understood that a fire temp WILL spike and that can't be avoided, but it's about how long we let the temps stay there? I'd assume that we would simply get into the habit of letting the fire either:

A) burn down to embers and then re-stocking (obviously spiking the heat when re-stocking the firebox)
B) be constantly flaming, adding wood as often as needed so that it is not only "embers." (keeping the temps
at as much of a constant as possible, (preferably apparently at a constant that is say around 650ºF or so),
but recognizing that the temps will spike during the adding of new wood.

The problem with "B" is that "overnight" there is bound to be an "ember" fire only in the morning. (Unless of course, most wood burning people get used to the idea of getting up twice or three times a night).

-Soupy1957

 

[Pagey]

You'll get more comfortable with "burn cycles" this winter if you do end up burning 24/7. I load up my stove about an hour before bed time (which means I load at about 9pm) when I am doing an overnight burn. My Endeavor will hold 8-10 small/medium splits loaded N/S. It usually takes around 20-30 minutes to get it settled in for the night, and once settled the stove top temp will peak around 650-700F for around an hour. Then it will settle into the 600F range for a while, then it will drop off to around 400F, which it seems to hold for the longest amount of time (several hours). I get up around 5am during the winter months, usually, and the stove will have about a 225-250F reading at this time with plenty of coals that I can rake to the front. Open the bypass, crack the door a little, and in no time those coals are red hot and ready to charge a fresh load.

It can be difficult to do at first, but these EPA stoves perform ideally when you let a load cycle through a full burn cycle. I find that adding a few splits here and there to keep the eye candy going results in a ton of coals that can be difficult to burn down.

But, yes, your stove temps will spike at the peak of the burn cycle on a fresh load of wood.

 

[Backwoods Savage]

To carry on from a previous Thread I started, but to focus more on the "high temp" issue:

There are two times in the burn cycle that I see as the highest temps being generated......
1) When re-loading the wood stove during the day time as needed for heat (multiple times per day)
2) When re-loading prior to bedtime (one load that needs to burn thru most of the night.

With regard to the first one, we wouldn't typically let the fire burn down to a smoulder, but keep a constant burn going. The temps WILL by nature jump, when the new splits are added, (typically a couple at a time anyway), and yet in MY particular case, I have found that if I try to achieve a Secondary Burn by closing down the Damper, it cuts out too much of the air and the fire doesn't seem to want to burn well. So I never really shut down the Damper much more than half, at most.

With regard to the second one, I've not mastered this yet, but I assume that I will, this year, since it will be our first 24/7 burning season. I see myself putting about 3 splits on the fire at about 10 PM, and then waking up to take a whiz at about 3 AM, and adding more.

In each case of re-stocking the fire, the temps are naturally gonna spike, and then burn down. Aren't we all really saying that it is understood that a fire temp WILL spike and that can't be avoided, but it's about how long we let the temps stay there? I'd assume that we would simply get into the habit of letting the fire either:

A) burn down to embers and then re-stocking (obviously spiking the heat when re-stocking the firebox)
B) be constantly flaming, adding wood as often as needed so that it is not only "embers." (keeping the temps
at as much of a constant as possible, (preferably apparently at a constant that is say around 650ºF or so),
but recognizing that the temps will spike during the adding of new wood.

The problem with "B" is that "overnight" there is bound to be an "ember" fire only in the morning. (Unless of course, most wood burning people get used to the idea of getting up twice or three times a night).

-Soupy1957

Well Soupy, the reason we put wood in the stove is to raise the temperature, so, yes, we all expect the temperature to spike. Without that, no heat.

The big problem with constantly adding wood before the stove gets down to just coals is that then the coals will continue to build up and you'll reach the point where you can't load as much wood because the firebox is too full of coals. Folks deal with this in various ways including (gasp!) shoveling out some coals and throwing them out with the ashes, which is the worst method.

One of the best methods of keeping the coals to a manageable level is to keep turning up the draft as the wood burns down. By the time the stovetop temperature gets down to 400 or so the draft can be open full. This will assist a lot to keep the coals down. We also rake through the coals a few times if necessary which will help them get more air. We'll also rake them towards the front of the stove.

"B" is not a problem and is what most of us find in the morning.

 

[firefighterjake]

Random thoughts:

The wood is often the key: Having good dry wood is really, really important. I mean there are several other factors when it comes to having a nice, long sustained secondary burn, but honestly good dry wood is crucially important . . . the stove, chimney height and size and a few other issues are all factors, but I cannot emphasize enough how much of a difference wood can make. In my first year of burning I was burning dead elm and I thought I did pretty well (and I think I did pretty well) . . . I was able to get secondary combustion often and could close down the air control to the quarter mark. However, in my second year of burning with wood that was over a year old I experienced burning nirvana . . . last year I could get long, hot secondary burns by completely closing the air lever . . . now granted part of this better experience may also have to do with the fact that I also now know how my stove burns, I can tell at what temps I can start closing the air, etc. . . . but I firmly believe having good, dry wood is really important if you wish to experience the "Bowels of Hell" effect where it looks as though a portal of Hell has just opened up in your woodstove.

Pagey has it right: It is much easier to run a woodstove 24/7 . . . for one thing your stove is almost always warm to hot . . . which means you have a draft established and the temp difference is not as great. Like Pagey my final re-load is usually timed to be around 9 p.m. -- a half hour or hour before I go to sleep for the night. I load up the stove, keep the air open and then gradually begin to close the air control until I can shut it down all the way . . . a process that typically takes 15-20 minutes. I then go to sleep and dream . . . . usually dreams where I am running, bears are mauling me or dreams where I look like Fabio rather than a fat, balding, bespectacled guy. I wake up around 5-5:45 a.m. and toss some kindling and splits on to the coals, open the air and wait for the fire to take off -- a process that takes 20-30 minutes . . . my wife however is even more patient than me as she bypasses the kindling and just tosses some small splits on the coals and waits . . . with the same results . . . just it takes a bit longer. As for the temp difference in the house . . . usually it's a bit cooler in the morning, but not bad . . . and just in case things get really, really cold at night I have my oil boiler set to come on at 60 degrees . . . although it is pretty rare to hear it kick on. Since my wife works part-time at nights she is typically home during the day to re-load the stove . . . and on one night each week she often stays up late at night as she is in the process of switching over from being awake during the day to being awake at night . . . and during this change over she re-loads the stove a couple times during the night . . . otherwise neither she or I wake up in the night to reload the stove.

Spiking temps: A lot of folks say if you have a woodstove you will experience fluctuations in the temp. I realize you'll see some temp fluctuations, but generally I don't see any wild extremes in temp . . . sure there is a spike in temps when you do a re-load vs. the temp you experience in the latter coaling stage after a long, overnight burn . . . but generally I don't see a huge change in temps from high, way-too-hot temps to freezing-my-butt off temps . . . I think part of the reason for this is that the steel-cast iron-soapstone stove "sucks" up the heat and slowly releases it even after the flames have died out . . . and then you have to figure that other objects in the room have also warmed up and "sucked" up the heat . . . and having a home well insulated to "trap" the heat is most definitely useful. Again, though, running 24/7 really helps you avoid the temp spikes.