More smoke with better wood. Help me figure this out!

[ikessky]

I know my old wood furnace is not like your EPA stoves, but you guys should have some idea as to what is going on here. First, a little about the install. I have a Daka add on-furnace that is hooked up to my central heat ducts. I have 1000-cfm worth of fans on the Daka. The combustion air is controlled by a door that is raised and lowered by a bi-metal coil t-stat. The theory is, you set the dial to a spot between Off and High. As the furnace heats up, the door is lowered and limits the air to the fire. The blowers kick on via a snap disc t-stat on the air jacket. Just as a note, the fans do not turn off until the fire is complete out and most of the coals are out too.

The furnace room is boxed in and there is probably not a lot of air movement in there. It does get plenty hot because of the radiant heat coming off the furnace and the stove pipe.

I'm burning hardwood that has been cut/split/stacked in the sun and wind for two summers now. Most pieces do not even have bark. When put on a bed of coals, it lights right away, and my magnetic thermometer on the stove pipe gets to 600° quicker than I've ever seen before.

Typically, I will load wood into the furnace, let it burn nice and hot (500°-600°) for a few minutes and then back the air down in stages. At the final stage, the door will typically be fully closed, but it does have two holes in it that are about 3/8" in diameter so it is not air tight. The last few nights, I've gone outside after my kindling fire and see very little smoke. However, once I load the furnace, I'm getting a fair amount of white smoke coming out of the chimney. There is no black or blue smoke and the chimney cap is remaining fairly clean.

What would you guys say is going on here? I'm keeping the air open too long and getting the furnace too hot so it shuts the air down too much? Not enough air movement in the furnace room for the intake air? Too much static pressure from the large fans and small 8" ducts off the top of the furnace keep the fire jacket too hot too long?

 

[Huntindog1]

First of all dryer wood out gases quicker.

Your furnace is not an efficient EPA type stove so your gonna get the smoke, it takes about 1000 deg to burn the smoke, we talk about stove top temps but thats not the temp of inside the insulated fire box as in these EPA stoves you get the temps up and inject secondary air up at the top of the stove and as the smoke rises it will re-burn as the temps are high and there is fresh oxygen coming into the stove thru the burn tubes.

What dryer wood really does for you is let the temps come up quicker, gets our type stoves into that smoke burning range of temps quicker. Once the smoke is burning thats another source of self perpetuating heat source so we can lower the primary air and let the logs at the bottom of the stove burn at a much lower rate, while the smoke gases keep burning at the top of the stove around those secondary air inlet tubes.

Wood gasifier wood furnance is the type you need to burn 90% efficient.

 

[Todd]

Could your white smoke actually be steam? If it dissipates quickly near your stack and not linger through your yard it's probably steam which is a sign of clean burning.

 

[ikessky]

I was wondering if maybe it all has something to do with the temps and the atmosphere. It's not overly cold (about 25°) and the wind was coming out of the northeast. Also, the smoke was dropping down instead of going up.
My main thing is that I don't want to be a bad neighbor. In the past 3 years, no one in my neighborhood has said anything about wood smoke and I'd like to keep it that way.

 

[Huntindog1]

When you were burning with kindling you most likely had higher fire box temps and the thinner pieces of kindling had lots of air space around each piece making for a much more efficient burn situation. The internal fire box temps is going to have to get to like 900 to 1000 to get no smoke.

 

[begreen]

Could your white smoke actually be steam? If it dissipates quickly near your stack and not linger through your yard it's probably steam which is a sign of clean burning.

Agreed. If the white smoke dissipates quickly, then it is likely steam vapors.

 

[Huntindog1]

Just noticed I over looked that your 600 deg temp was your flue temp so that would indicate your fire box temp should be high enough so like Begreen and Todd said its gotta be steam I would think also.

 

[Ashful]

I was also thinking steam, but then I don't understand the question or problem, either. Seeing you've been on hearth.com since 2008, are we discussing a furnace that is new to you, or one you've been burning several years? Is this a new problem, or just a symptom you've always noticed?

 

[ikessky]

I think maybe I just get too nervous every year! I'm trying to be a good neighbor/citizen by limiting smoke coming out of my chimney. I cannot afford an EPA furnace right now, so I'm doing the best I can with what I've got.
I don't appear to be blanketing the neighborhood, nor do I have hazy blue smoke and a clogged chimney cap like the people down the road, so maybe I'm overthinking this all and just need to get back to heating my house.

 

[Backwoods Savage]

Good for you to be concerned about the neighbors.

More than likely you are correct with getting nervous every year. Don't forget, every time you load the stove moisture evaporates and even with the new EPA stoves, on reloads we are going to see smoke out the chimney. On ours, we typically turn the draft down and engage the catalyst after maybe 5 minutes and sometimes less and once we do, there is no more smoke out the chimney. WARNING: This 5 minutes should not be taken that everyone can do it. It all depends upon the wood and the stove.