Too much draft?

[pmancoll]

My fires burn too fast and I think I'm losing a lot of the heat up the flue. I think there might be too much draft. It seems like the stove uses up the wood real fast and I don't want to just waste the wood I went through so much trouble to split and store.

Background:
A couple of months ago, I had a Kodiak 1700 Insert half-installed with an insulated 6" SS liner straight up a 20 foot chimney. I say half-installed, because they are going to come back and install the block-off plate and replace the crown on top of the chimney. After 2.5 months, they finally got back in touch with me and want to do the second half of the install (and also collect the second half of the payment).

Draft: The stove is in the basement, my house is by no means airtight. Smoke used to come out when I would start a fire when the stove was cold, but I followed some advice in these forums and use a propane torch before lighting a fire to get the draft going. I don't have any smoke problems now.

There's no separate control for the secondary air tubes on the stove insert.

Pictures & Videos:
-- Does this pic show the flame and heat going up the flue and being wasted?
http://www.flickr.com/photos/21339555@N06/3386361014/in/set-72157615904575506

-- A video that I think shows my precious heat going up the flue.

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.

Accept third party cookies

-- The hole where the blockoff plate will be:
http://www.flickr.com/photos/21339555@N06/3386361056/in/set-72157615904575506


So, do I have too much draft? Any tests I should do? Anything I should ask the installers to do when they come back?

Any help / advice would be very much appreciated!

 

[jtp10181]

Its normal for the fire to roll up around the edge like that. Do you notice a difference in the fire when you adjust the burn rate (air control)?

Also if you have a hard time getting the fire going, I don't see how you could have too much draft. How tall is the chimney anyway, you did not mention.

 

[pmancoll]

20 foot chimney. There is only one air control on the Kodiak, which lets in air from the front-center of the stove below the door. When I push the control in, it slows down the fire: at first the flames shoot out the secondary tubes, then the fire seems to burn mostly only at the top and the bottom parts of the fire will turn off or get cold. Then, it seems like a lot of unburnt smoke goes up the chimney.

However, last night, my fire was really going, I closed the air control almost all the way (90%), and the fire pretty much kept on going on - It burnt through three logs in about 45 minutes (with the control closed)

 

[jtp10181]

Sounds about normal to me. What kind of wood are you burning, how long has it been split, and how much are you putting in the firebox?

 

[pmancoll]

I'm burning oak (post oak or hickory). It was split and stacked about two years ago, but it's stacked in a mostly shaded area, I live in a humid area, etc I got 15% when I used (and bent the pins on) a cheap moisture meter on the wood.

The stove manual says "4. For maximum efficiency: When the stove is hot, load it fully to the top of the door opening and burn at medium low settings. when the fuel is mostly consumed, leaving a bed of red coals, repeat the process. Maximum heat for minimum fuel occurs when the stove top temperature is between 250 F and 550 F".

So, I tried that, and the wood seemed to either smolder (when the airflow was at the low setting) or burn up within an hour (when the airflow was higher).

I used an IR thermometer and got readings in the 300s for the stove top and 100's for the flue collar.

I can get fire a started without the propane torch, but I use it to make sure I don't get smoke in the basement.

Also, the manual said something about using a water column gauge to measure the draft, but I don't have one (or know how to use one). There also isn't a recommended draft range that the chimney should have (in whatever units draft would be measured in)

 

[BrotherBart]

Everything you describe screams "wet wood". If that wood was uncovered this past summer it didn't have a chance in hell to be dry. I live near D.C. and it poured rain here all summer. The surface moisture on the wood means nothing. Split one of those splits in half and immediately get a reading from the center. An oak split will measure 15% on the outside surface within days of being a live standing tree while the inside of it will be 35% or more.

With that coal bed and the flames on those splits if that is anywhere near dry would the stove top on that Kodiak would be kicking in 500-600 degree territory.

Where do ya live? Just the town.

 

[jtp10181]

BB, lets not jump the gun here ;-)

woodburnNearDC, Do you get a lot of black on the door/glass or inside the stove and on the top half of the bricks?

Burn a smallish fire to get a good bed of coals and warm up the stove. Load it up good and leave the air open for 10-15 minutes to get everything charred. Then try turning it down slowly and watch how it effects the fire. You want to find the sweet spot where its not smoldering but burning nice and slow.

 

[pmancoll]

I got 15% on the inside right after I had split it (although, I don't 100% trust the NEIKO meter)

The surface that I took the stovetop temperature has a an airspace that fan air blows out from in between it (the very top) and the lower top (the metal casing on the outside of the firebox). So, maybe that explains why the top area isn't that hot. I can test again later and take the temperature on the side of the stove.

With our weather, I could see how the wood could be too wet: besides the stovetop temp, are there other ways wet wood explains what I'm seeing?

I live in Falls Church (Fairfax county, not Falls Church city), near Annandale. Ah, Northern VA, where it can take a sentence just to say your town :=)

 

[jtp10181]

Answer my last question I can tell you the answer...

I think BB jumped the gun on the wet wood diagnosis personally.

Also, are you running the fan? Don't. Wait till you get the stove really hot and get the hang of running it correctly. Fan just cools down the shell and is going to make it harder to figure out how to use it.

 

[pmancoll]

JTP: I get some black on the glass sometimes when the fire is starting or after a new batch of wood is put in. Also, there is often hissing as the wood heats up (the water in the wood boiling?). However, the black burns away once the fire is hot. There is usually an outline of black around the bottom left corner (the door opens on the right, the hinge being on the left).

I'm not home now, but I can try out what you suggest (burning a smallish fire to get coals, loading it up good, etc) later, take notes and post back.

One thing your and BB's posts make me think of: maybe it's that my wood is wet and I'm keeping the air open for a long time because I'm waiting for the water to boil out and for the wood to be fully ignited. By that time, so much of the wood is on fire, that throttling the air control down then doesn't make the wood last that long.

Also, maybe the hole where the blockoff plate will be and the fact the fireplace is on the side of the house and mostly underground is keeping the stove cooler than it should be.

 

[pmancoll]

haha, "BB gun", I get the pun. Anyways, thanks to you both for your answers so far.

JTP: How hot should I let the stove get before I can be sure it's hot enough to be running well? 450? 500F? By the way, I've never seen the flue glow, so I guess it's never "overfired".

I'm still fascinated by the idea that a "water column gauge" could directly measure the draft, but I guess that would probably depend on the weather and how ice cold the stove is when measuring.

 

[BrotherBart]

Now that I know it is an insert the stove top temp doesn't count. But I stand by the wet wood diagnosis. We were a swamp all summer. If that stuff wasn't top covered it ain't dry. It is taking most of the heat to dry the wood and when you throttle it down the moisture is killing the secondary burn and causing the smoking. And taking a lot of air to keep the fire going in the process which is a double whammy since the cool primary air cools the firebox even as it supports the flames.

If I still commuted by there every day I would stop and light off a load and take a look. Smack a couple of those splits together and see it you hear a "thud". If you do, it is the wood.

 

[jtp10181]

I still want an answer to the questions about the glass "Do you get a lot of black on the door/glass or inside the stove and on the top half of the bricks?"

Yes 450-500 would be warmed up.

Pressure differences can be measured in inches of water column. So the pressure difference from the flue to the room would show how much draft there is.

 

[pmancoll]

Ok, I'll see how wet the wood sounds tonight. And this weekend, I'll try out a fire while keeping an eye for soot.

 

[jtp10181]

You would know if the glass is getting black. You would not be able to see through it when you are done burning a fire...

 

[BrotherBart]

I am sitting here watching three large oaks splits rolling at 550 stove top for the last two hours, and will be until three or four in the morning, in a stove pretty much the same as yours. With a 21 foot liner and I am 18 or 19 mile away from you. Which means as warm as it is out tonight I screwed up and we will roast upstairs tonight.

Since the Kodiak is burned N/S like I burn the 30 any hissing and stuff on the glass support the wet wood theory. The crap boils out of the end in front and crunks up the glass. By the way this is the first time I have ever said anything about wet wood here on the forum. I went through the same thing you are going through year before last because I always had cut my red and white oak in the spring and burned it the next season. Had a hell of a time with the new EPA stove leveling out a burn, hissing, black spots on the edges of the glass, couldn't get it hot and the whole mess. I got two years ahead on wood and keep it top covered and haven't cleaned that glass since the day before the eight degree nights in January. And the stove is up to temp and rolling in around 45 minutes time.

 

[jtp10181]

Just FYI, I wasn't saying it can't be wet wood. Just that more questions needed to be asked before making a determination. I am pretty analytical and like to gather all the facts before I come up with an idea.

 

[gzecc]

Touch the moisture meter to your fingers, you should get around 30% unless they are wet or very dry. Next touch it to some interior wood work in your house. You shoud get a real low number <15%. Next touch it to some fresh cut firewood (interior) It should be high >35-40%. This is how you will get a feel for your gage.
I doubt your oak is 15% MC.

 

[jtp10181]

JTP: I get some black on the glass sometimes when the fire is starting or after a new batch of wood is put in. Also, there is often hissing as the wood heats up (the water in the wood boiling?).

Wow I totally missed this before. I was just reviewing the thread and noticed this. Definitely wet wood. Now I feel like an idiot.

BTW, yes that is water boiling.

 

[pmancoll]

In Summary, I found out that the tarp I was using to cover the wood was letting moisture through:

I don't have much outside covered storage (no garage, no shed) so I cover my small wood pile with a tarp. It rained on Friday and when I pulled up the tarp to look at the wood, I noticed that the top of the wood pile was all wet. The tarp had seemed to work well on snow, though. After seeing that on Friday night, I didn't really feel like starting a fire with the visibly soggy wood...

So, the inside of the splits I'd been testing might actually be as dry if not drier than the layers towards the outside.

All that time I spent hand splitting the wood (learning how to split), stacking it, waiting, I just wasn't looking for the wood to still be wet ... Oh well, there is next year.

Thanks again for diagnostics!

 

[Todd]

Just another thing to add is, it takes some time to figure out how your stove works best. There are different loading technique's and constant tweaking of the air control at diffent times to figure out your sweet spot. Experimentation, and some trial and error is common place with a new stove. Heck, I've had this stove 3 years now and I am still learning.