How Soon to Cut Air?

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Caw

Minister of Fire
May 26, 2020
1,021
Massachusetts
I'm a new wood burner this season learning the ropes. I only have probably 25 ish fires under my belt but feeling more confident every time. I have an Osburn 1600 insert that hums along pretty nicely between 400-550 degrees stovetop.

Ive put a lot of time into properly preparing my wood so now Im working on maximizing the BTUs from each load. So, assuming properly dried wood, when do I want to start cutting air? I've seen lots of different answers. Also keep in mind this time of year im mostly starting with a cold firebox. This question is much easier on reloads.

Do I go by stovetop temp? I don't have a pipe or flue thermometer as its an insert but my insert does protrude quite a bit due to the masonry. My stove top thermometer is pretty close to the middle of the unit.

Do I just go by how the fire looks? I've tried doing this and kind of ignoring the temp and it can often lead to decent secondaries but it doesn't feel right. I keep feeling I need to get up to temp first.

Ive also noticed the type of wood matters a lot. Right now im burning poplar from my own property. Its hot and fast but doesn't last long...perfect for the 40 degree nights. I have a couple cords of good, dry maple and oak for the real cold. I get much better temps and longer secondaries with the hardwood.

Thanks for the replies. Im just trying to maximize my skills here as quickly as I can!
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,618
South Puget Sound, WA
I think the "stove top" for this insert is actually the top of the convection jacket. Is there an airspace under the top of the stove from which the hot air blows out? If yes, then putting a thermometer on the stove face above the door corner will give a more accurate reading. Yes, go by stove temp, but also the fire itself.

Cut down the air fairly aggressively as long as it doesn't snuff the flames completely.
 

Caw

Minister of Fire
May 26, 2020
1,021
Massachusetts
20201027_203730.jpg
I think its the actual stovetop. The air comes from the gap between the facing and the stovetop so the jacket sits behind the facing.

Thanks for the link!
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,618
South Puget Sound, WA
Great. If that is the case then you're fine with that location.
 

Caw

Minister of Fire
May 26, 2020
1,021
Massachusetts
Great. If that is the case then you're fine with that location.

Some good points in your link there. I didnt think about the lag time of the analog stove top thermometer...it takes time for the box to heat up. Waiting for it to get to 300+ to shut the air I'll be way too late and missing out on secondary time.
 

Caw

Minister of Fire
May 26, 2020
1,021
Massachusetts
Great. If that is the case then you're fine with that location.

I do have one more question about air if I may:

How long should I leave the air closed during the coaling phase? I've been opening the air up once the flames are done to minimize my coal bed. Am I missing out on some heat by doing so?
 

Highbeam

Minister of Fire
Dec 28, 2006
19,326
Mt. Rainier Foothills, WA
Also realize that when the blower is running and blowing on your stove top meter that it artificially lowers the reading.
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,618
South Puget Sound, WA
I do have one more question about air if I may:

How long should I leave the air closed during the coaling phase? I've been opening the air up once the flames are done to minimize my coal bed. Am I missing out on some heat by doing so?
I do that sometimes and other times I leave the air where it is and put in a couple of skinny 2" splits on the fire to help burn down the coals.