Stove temp drops fast

[Flashback87]

I'm about 2 months in with my true north tn20. Very pleased with the stove and heat output but I'm still trying to get a hang of the control and proper settings.

The problem I'm having is I'll load load on a bed of coals, gradually close the air and when it gets to a little over 700 stove top temp I'll close the air control 3/4 of the way or all the way closed. When i do this, the temp starts to drop kind of fast. I'll be in the lower 600s to upper 500s pretty quick like 10-15 minutes. So, the secondary burn is not as intense and I just have some lazy flames.

What I'm trying to undertand is if this is just normal. I would think that the temp should hover around a higher temp for awhile but I may be wrong.

What do you think?

I'm using hard wood. A lot of locust, maple and red oak. The ones I split at room temp and check are less then 20% moisture. Don't check them all but it seems most are seasoned.

Thanks!

 

[FPX Dude]

Let it run a bit more before you close it down. Sometimes if not dry enough wood too.

 

[Flashback87]

Let it run a bit more before you close it down. Sometimes if not dry enough wood too.

So, I should let the stove top temp get higher before closing the air supply down?

I get a little concerned with overfiring but this concern may be unwarranted. I emailed true north for some guidance on this subject of overfiring and they provided no firm temps. The manual says turning red is an overfiring condition.

I try to keep it under 750.

 

[kennyp2339]

Wood split size, shape, thickness along with species and dryness are all contributing factors, generally speaking when I burn maple, ash, cherry I'll have lower end temps once I establish the fire and set the air to the setting I like, I get hotter stove top temps when I burn red & white oak, or black locust on the same lower air settings.
I personally think how your running your stove is pretty much text book perfect, maybe a trick would be to do all of that, get your burn settling in and again after the temps go down and the stove is rolling, increase the air going into the stove by 1/10th increments, until you get your desired stove top temp, so you start up, you go down with air then do a bump or to back up and let is work itself in 15-20min increments.

 

[Corey]

Sounds like you just need to shut it down at a slower pace. If you're going from wide open, down to mostly closed in one step, then that is probably too quick. If you hit 700°F, you might close 1/4 to start with and give the stove ~10 minutes to catch up. Then close to 1/2 and another 10 minutes, etc.

Wood is a 'dynamic' fuel. On a fresh load, a lot of very volatile gasses come off and can create a big flair up of flames, but it is also pretty easy to snuff that out by closing down the air too quickly. As the wood lights off and chars, you get into heavier and heavier gasses and ultimately, you are burning charcoal which won't react much to fairly wide changes in airflow.

But, overall - small, stepwise changes over 10-15 minute time periods are better than suddenly snapping the air closed.

 

[Flashback87]

All good info... thanks!

I usually turn it down in quarter increments and then when I see the temp start to fall I will open it back up after being closed or all the way closed. I will try smaller increments and probably just need to experiment. Definitely a lot of variable and no load is the same.

I just thought there would be a stage where I could just let it cruise for awhile. Maybe I just didn't realize there would be so much user input with the air control.

All in all, it gives me good heat and have no issues relighting in the morning from coals, I just thought i could cruise longer with the air closed or almost closed. But the stove has exceded expectation.

 

[Corey]

It is a bit tricky to learn. The way I view it is that there is an optimal curve for airflow vs how much wood is actually burning. You should get to a point where you are shutting the air flow down and the stove keeps getting hotter. (You are flushing less cold room air through the stove) When you see that, you know you are on top of the curve. If you're closing air and the stove is getting colder, you know you're under the curve.

Once you get a good coal bed and the fresh load has been through the initial flair up stage and has a good char, that should be a pretty consistent cruise stage with even heat until the wood turns to coals and temps start to fall.

 

[begreen]

I can not close down the air all the way when burning locust. It's too dense. Try closing down the air sooner, with the final setting a bit more open when burning extra hard wood. It's better to go by flue temp than stovetop temp, but if going by STT, then start closing it down around 500º instead of 700º. As the stove air is closed down and secondary burn kicks in, the stovetop temp will continue to rise.

 

[Flashback87]

I can not close down the air all the way when burning locust. It's too dense. Try closing down the air sooner, with the final setting a bit more open when burning extra hard wood. It's better to go by flue temp than stovetop temp, but if going by STT, then start closing it down around 500º instead of 700º. As the stove air is closed down and secondary burn kicks in, the stovetop temp will continue to rise.

This is good info about the locust because I have a lot of locust.

I'm probably just overthinking this. I just reloaded about 1 hour ago around 12 with stove top at 300. Started turning down in smaller increments when stove top was 450-500. Probably adjusted air 3-4 times until a little past half closed. And put blower on. Temp rose to 730 so I almost closed it all the way and it started to drop pretty good

This is where I'm at now. Big soft maple split in middle, locust split on right and some unknown hardwood on left. Stove top temp on right is around 650 and left is 575ish.

Should I be hovering at a higher temp then this?

Wondering if I shouldn't have shut it down so fast when I got to 730.

I appreciate all the guidance and things to try. Again, I'm pleased with the stove and getting good heat so I guess I'm just fine tuning this thing.

Stove is in existing fireplace so I can only take stove top temp unless I look up chimney with infrared gun.

Thanks!

 

[begreen]

Wondering if I shouldn't have shut it down so fast when I got to 730.

Usually in that case, opening up the air a little, say 1/4-1/2" will be enough air to revive the fire in 5-10 minutes.