Proper Burning Techniques, part 2

[SolaGracia]

OK, so now that I have a little more experience, I did a burn and collected data every 10 minutes. I did fiddle with the controls a bit, but this is about the best I can do. I am curious if the collective opinion is that this was a bad, decent (average), or good burn. It's about the best I have gotten so far, with my suspect wood. That is, just under 4 hrs useful burn. Still very far from getting a useful overnight, when I cannot fiddle as much as I did here, opening and closing the air control.

Attached some graphs also.

3 oak splits, 3 cherry splits. Total weight, 32 lbs. Loaded E-W, 2 in back, 2 in middle, one in front until 7:30
Started at 300F, after burning down most coals in front then spreading around before reloading
Outside Temp @ 6:50: 15F, Wind 10 mph, feels like 5F.
Outside Temp @10:30: 12F, Wind 10 mph, feels like 0F.
Stove Thermometer measures 415F in a 350F oven. I think stove top is ~150F hotter than where the thermometer
is, so thermometer should be measuring 85F less than actual top temps, since it is on the front of the insert.

Time Stove Temp House Temp Fan Speed Air control Fire status notes

6:50 300 66 low open front right only
7:00 300 66 low open front across to middle
7:10 360 67 low open full 2 rows
7:20 460 68 low open full all
7:30 485 70 low/high 3/8 full all Added 6th log. After going to 3/8, the flames died and temps started dropping, so increased to 5/8
7:40 450 68 low 5/8 light
7:50 490 68 low 5/8 light
8:00 525 69 low 5/8 same
8:10 545 69 low 1/2 same
8:20 510 69 low 1/2 same
8:30 475 68 low 1/2 lighter
8:40 450 68 low 5/8 very light Back two and top middle are whole but completely charcoaled---others have almost vanished into coals
8:50 410 67 low 5/8 same
9:00 400 67 low 5/8 same
9:10 360 67 low 3/4 same
9:20 350 67 low 3/4 same
9:30 340 66 low open same
9:40 325 66 low open almost none
9:50 300 66 low open almost none
10:00 290 65 low open none Pulled all remaining coals into pile at front
10:10 290 65 low open some
10:20 300 65 low open some Pulled coals together again
10:30 300 65 low open some
10:40 300 65 low open none Natural Gas fired up when temp dipped below 65F. Reload time.

 

[begreen]

Not bad with a blower running, especially if the wood is not fully seasoned. The tighter you can pack the firebox, the less airspace and longer the burn. One exception noted, the wood orientation. By the description, it sounds like the stove is being loaded E/W, not N/S. Try a full load, rotated 90°, butt ends of the wood facing the glass (S). That may allow the air to be closed further during peak burn.

 

[SolaGracia]

Correct, the load was E-W not N-S.

 

[woodgeek]

You probably know that adding a log on the way up to peak temp is less than ideal--even though its fuel, its cold and soaks up a lot of heat while the other logs are now heated to a proper temp for proper combustion. The air influx while the door open also cools the the flue and sets your draft back (at a constant air setting, why you had to reopen). As BG said, better to load full up at the beginning, and find the split size/ load orientation/ packing density that allows a rapid (i.e. less smoky) takeoff to a happy cruising temp.

 

[Martin Strand III]

OK, so now that I have a little more experience, I did a burn and collected data every 10 minutes. I did fiddle with the controls a bit, but this is about the best I can do. I am curious if the collective opinion is that this was a bad, decent (average), or good burn. It's about the best I have gotten so far, with my suspect wood. That is, just under 4 hrs useful burn. Still very far from getting a useful overnight, when I cannot fiddle as much as I did here, opening and closing the air control.

Attached some graphs also.

3 oak splits, 3 cherry splits. Total weight, 32 lbs. Loaded E-W, 2 in back, 2 in middle, one in front until 7:30
Started at 300F, after burning down most coals in front then spreading around before reloading
Outside Temp @ 6:50: 15F, Wind 10 mph, feels like 5F.
Outside Temp @10:30: 12F, Wind 10 mph, feels like 0F.
Stove Thermometer measures 415F in a 350F oven. I think stove top is ~150F hotter than where the thermometer
is, so thermometer should be measuring 85F less than actual top temps, since it is on the front of the insert.

Time Stove Temp House Temp Fan Speed Air control Fire status notes

6:50 300 66 low open front right only
7:00 300 66 low open front across to middle
7:10 360 67 low open full 2 rows
7:20 460 68 low open full all
7:30 485 70 low/high 3/8 full all Added 6th log. After going to 3/8, the flames died and temps started dropping, so increased to 5/8
7:40 450 68 low 5/8 light
7:50 490 68 low 5/8 light
8:00 525 69 low 5/8 same
8:10 545 69 low 1/2 same
8:20 510 69 low 1/2 same
8:30 475 68 low 1/2 lighter
8:40 450 68 low 5/8 very light Back two and top middle are whole but completely charcoaled---others have almost vanished into coals
8:50 410 67 low 5/8 same
9:00 400 67 low 5/8 same
9:10 360 67 low 3/4 same
9:20 350 67 low 3/4 same
9:30 340 66 low open same
9:40 325 66 low open almost none
9:50 300 66 low open almost none
10:00 290 65 low open none Pulled all remaining coals into pile at front
10:10 290 65 low open some
10:20 300 65 low open some Pulled coals together again
10:30 300 65 low open some
10:40 300 65 low open none Natural Gas fired up when temp dipped below 65F. Reload time.

WAY over the top!

If our fore fathers had to analyze and compute this type of (unnecessary) data to build a fire, they would not have survived and we would not be here now.

Building an acceptable fire in a modern metal wood stove to help heat your house is not that complicated.

First, start with dry firewood. Make some small kindling.
Stack it in the firebox with air spaces between the pieces, larger ones on the bottom, kindling on top.
Fully open the incoming air and the damper.
Ignite the kindling using some loose paper or cardboard.
Leave the door open a crack to help it get going, then close it.
Let it get hot, then close down incoming air to regulate the temperature.

The only difficulty I can think of is if your stove and chimney are on an outside wall making for a cold chimney for start up or, possibly, in a basement where negative pressure is often an issue. Chimneys should be warm to start a fire which means having the unit installed near the center of the house and basement installations can be tricky.

Aye,
Marty
Grandma used to say, "Work smarter, not harder."

 

[SolaGracia]

Marty,

It seems pretty common here to see people who have never burned with fireplace inserts wondering whether or not they are getting a "normal" or optimal result. Having no standard to base my insert's behavior on, I come again to one of my favorite sayings.

"You don't know what you don't know"

So, I really would just like to know if the burn cycle I posted (mostly in terms of insert temps) is along the line of normal for you folks who know what you are doing.

Thanks!

 

[SolaGracia]

You probably know that adding a log on the way up to peak temp is less than ideal

I didn't really realize that it was so detrimental. Thinking about it, I understand it probably isn't the best idea.

Thanks!

 

[Martin Strand III]

Marty,

It seems pretty common here to see people who have never burned with fireplace inserts wondering whether or not they are getting a "normal" or optimal result. Having no standard to base my insert's behavior on, I come again to one of my favorite sayings.

"You don't know what you don't know"

So, I really would just like to know if the burn cycle I posted (mostly in terms of insert temps) is along the line of normal for you folks who know what you are doing.

Thanks!

SG:

I believe most people have no idea of what temps their units achieve in a typical burn cycle let alone many simple safety issues concerning same. And since "operator error" is the most common source of wood stove blunders, it reminds me of what Grandma used to say:

"Play with fire and you'll get burned."

You would think logical and rational adults would take the time and make at least some effort to learn about the various advantageous functions as well as the dangers of their stove before striking a match and putting their home and loved ones at considerable risk; akin to obtaining the training to get a driver's license before putting your family in the car for a cross country trip which all reminds me of what Granpa used to say:

"We have seen the enemy. It is us."

By putting forth much data, many will be confused which reminds me of one of my favorite sayings

"Common sense is not so common."

Aye,
Marty

 

[PNWBurner]

The temperature trajectory you posted is about what I usually see. But my temperatures are usually about 100 degrees higher at each point along the way. As I understand your post it sounds like you think the actual temps might be higher than what you recorded so that makes sense.

Your 12F is much colder than our usual 35-45F but I suprised your house temp. isn't quite a bit higher. Ours woud be in the mid-upper 70s after a burn like that.

Had you been burning for while before your test load? Or was this the first load after a kindling startup?

Your 32 lbs. of wood probably amounted to something like 150,000 BTU (assuming 5,000 BTU per pound which might be low). Maybe it's still pretty wet which is taking up lots of heat?

 

[SolaGracia]

Your 12F is much colder than our usual 35-45F but I'm surprised your house temp. isn't quite a bit higher. Ours would be in the mid-upper 70s after a burn like that.

I had been burning all day. I have 2600 sq ft., with large old inefficient windows, and poorly insulated attic. It's pretty bad. I am surprised its as high as it is. 66F-67F with wood heat is a lot more comfortable than the same with natural gas heat. If I keep the blower on high, it will get to 72F-74F, for a short time, but the insert cools off much more quickly.

Thanks!

 

[pyper]

Stack it in the firebox with air spaces between the pieces, larger ones on the bottom, kindling on top.

I never would have thought of putting kindling on top. Is that what works best?

 

[Martin Strand III]

Stack it in the firebox with air spaces between the pieces, larger ones on the bottom, kindling on top.

I never would have thought of putting kindling on top. Is that what works best?

Get with it , man!

Look up (Google, etc.) "top down method" for building fires or look here:

http://mha-net.org/html/p-bush01.htm

Aye,
Marty

 

[pyper]

Thanks!

Here's a good article I found:

http://www.csia.org/HomeownerResour...HOWTOBuildaTopDownBurn/tabid/229/Default.aspx

I'll give it a try tonight.