Another dirty glass question - C450

[danham]

I've read many of the posts here about dirty glass and have tried to eliminate the obvious causes: my 2-year-old wood tests at around 16%, I get good secondaries, no gasket issues, no obvious problems with glass wash outlets. Pro sweep ran a camera and brush up my liner (not insulated, but chimney is interior) and found no creosote after a season. But my glass is filthy.

So I wonder if I'm just burning with too little draft, or if I need to move wood farther back in the firebox, or both. My usual routine is to leave the door unlatched and barely open until I can hear it being pulled shut by draft -- this takes about 1-2 minutes from a cold start. Then close the door fully and leave draft wide open until everything is burning nicely, then drop to about half, wait a few minutes, drop down to about 25% open or where secondaries are doing well but main flames are not "choked." This is with fairly small loads (which may also be an issue).

Your thoughts and suggestions welcome.

-dan

 

[Dieselhead]

Have you talked to other similar stove owners? Could just be a inherent design flaw with your particular model stove?
as a side note, I stopped worrying about dirty glass almost right away. Maybe lasted a week. After all I use it for heat and not ambiance. As long as it’s pumping out the btu it’s doing it’s job and that to me at least comes first. I do clean it at the end of the burning season so it looks nice until the fall at least.

 

[begreen]

The small loads could be the issue. It takes time to fully warm up the mass of the stove. Take a picture of the next loading and post it here. Another possibility is that the draft is weak. This could be caused from burning when it's mild outside (50º), to a cap screen that is starting to plug.

 

[Kevin Weis]

Right off maybe not enough air going through the air wash for the glass. Running it too low? This with no other issues such as wet wood. Smoke is rolling around in the stove and condensing on the cooler glass it sounds like.

 

[Ctwoodtick]

I have the Jotul 550 (I think a little different than the 450) about 10 yrs. All I get some blackening of the glass on the bottom but this is due to some slight warping of the face of stove. Aside from that, I just take a damp paper towel and wipe away the light fly ash film on the glass. Even if you’re getting some dark glass, a day or so of good fire should burn that off to near clean. If the glass is darkening then in just one spot, sound like air is getting in near that spot. Use full loads though.

 

[ctreitzell]

cleaning the window ceramic is the Panadero forté

the Panadero baffle directs the flames to the front of the stove so flames are continually licking the inside of the door which equals burning off most of whatever crud builds up on the inside of the window...shut the air flow down, tho...which in turn reduces or stops the flames and get a smolder going and brown and black starts to build up...a delicate balance of air intake alongside hopes of low moisture content fuel

 

[oilcan1001]

I am still getting to know my new to me Drolet Escape 1800. Different stove than yours but I was having the exact same issue. My draft is not strong but is sufficient.
My solution =
from a cold start - leave my door ajar a couple inches until flames are STRONG. This time can vary from 5-15 min depending on my wood type and amount of kindling used.
reload - leave door ajar until flames are STRONG and smoke is non existent. Usually about 1-3 minutes
ps I don't start closing off air until everything is very established

My glass now stays pretty clean now even after days of burning, except for a very small area in the bottom corners.

 

[xman23]

Give it a few years and it might get better. That's what mine took. And it was very black, and thought I would have blacken glass after every fire. So then very slowly, it started to get better. I mean year 2-3 years. What happened is the wood got better. And I guess we burn hotter. Plus all the tips above helped.

Now if we ever get a fire to accidentally smolder and blacken the glass, I can burn if off with a few reloads with a hot fire. And that is very rare. Mostly a little white haze that washes off with water.

 

[danham]

The small loads could be the issue. It takes time to fully warm up the mass of the stove. Take a picture of the next loading and post it here. Another possibility is that the draft is weak. This could be caused from burning when it's mild outside (50º), to a cap screen that is starting to plug.

All of the replies have been helpful, but this one I think is what I need to pursue first. The problem is definitely worse when it's mild outside. Ive been burning when it's about 45 out. So if the predicted cold snap arrives next week, I'll load up and try again, with the draft open longer. Thanks everyone and Happy New Year.

-dan

 

[Woody5506]

I would say rather than the first adjustment going down to about half open, give it an extra step and only drop it a quarter shut. Let it settle in for another few minutes, then drop to 50% and so on. With my stove, I really don't shut it down completely until maybe the fire has settled in for about an hour, sometimes more. If I'm in a rush, it can be 45 mins before turned all the way down, but typically that's going to result in a less than ideal burn, and more likely blackened glass.

 

[NickW]

Smaller loads I always leave the air a little more open than full loads. Same with lower quality wood. You have to keep the temperature up long enough to keep the secondaries firing until the coaling stage. Any wood fibers left after the temps drop will smolder and gunk up the glass (and flue...). Cold starts make sure every piece of wood is charred before starting to close the air (without over firing).

 

[Caw]

Smaller loads I always leave the air a little more open than full loads. Same with lower quality wood. You have to keep the temperature up long enough to keep the secondaries firing until the coaling stage. Any wood fibers left after the temps drop will smolder and gunk up the glass (and flue...). Cold starts make sure every piece of wood is charred before starting to close the air (without over firing).

This is key. More air when it's mild out. It's ok to shut it down normally during the main off gassing stage but once that dies down you should open the air back up a bit before leaving it to finish the cycle. You won't have any more glass issues if the draft and wood are fine.

 

[bigealta]

Yes with everything so far. Big full load will burn off any black creasote on the glass. If it's just gray/brown ash dust this is ok. Just wipe off with damp paper towel. If it doesn't easily wipe off then the full hot fire with dry seasoned wood will do the trick. And yes closing down draft in slower stages should help too.

 

[danham]

More good advice; thanks! The crud on the glass is very dark brown, but not black. As soon as it gets cold out again, I will apply all these suggestions.

-dan