How do I keep PH glass clean?

Brick (ware)House · Jan 1, 2014

So how clean is the "self-cleaning glass" supposed to be? Obviously I can see fire through it but the glass on my PH is not staying what I would call clean. Every time the stove cools I get in there with cleaner and paper towels to remove a layer of crud. If I recall a "hot" fire is required to maintain clean glass. Does anyone have any idea at what temp the glass will clear? Am I possibly doing something to render the air wash system ineffective?

I have had a handful of fires hot enough to make the andirons begin to glow (is this something to be concerned about?) so I would have thought that would burn off the window but no luck. Thanks for any advice.

weatherguy · Jan 1, 2014

How seasoned is your wood and did you test the door gasket to make sure its tight all around?

webbie · Jan 1, 2014

Also, the definition of clean can vary. Some people think it's clean if they can monitor the fire in a basic way. Others want it to be perfectly clear. The second is difficult in most cases unless you are running a stove hot. In general, using less wood (limit wood) and more air will keep the glass cleaner.

weatherguy · Jan 1, 2014

My glass gets dirty in the shoulder season when I burn low, once the real cold gets here I clean the glass with a wet rag and ashes and it stays crystal clear the rest of the year. The only other times my glass didn't stay clear was when I burned less than seasoned wood or when my door didn't pass the dollar bill test.

fire_man · Jan 1, 2014

Keeping the glass clean on the PH has been more of a challenge than I remember from the FV. My wood is definitely seasoned 3+ years so it's not the wood. The funny thing is the glass seems to have developed a permanent hazy etch that is very difficult to remove.

Brick (ware)House · Jan 1, 2014

weatherguy said:
How seasoned is your wood and did you test the door gasket to make sure its tight all around?

The door gasket was so tight I almost couldn't latch the door when the stove arrived three weeks ago. It has loosened up a bit since then but I hadn't thought to check it yet. I will do that and see if there are any loose spots.

Wood is elm that was bark off, standing dead cut and split late summer. Looks and feels thoroughly dry. I have a few loads of 3+ year oak so I can run some of that and see what happens. I do run the damper full closed almost all of the time and close down relatively quick on reloads because of a strong draft. I have never observed any smoke out the stack but obviously can't look at it during reloads or cold starts (have only done that three times).

Brick (ware)House · Jan 1, 2014

webbie said:
Also, the definition of clean can vary. Some people think it's clean if they can monitor the fire in a basic way. Others want it to be perfectly clear. The second is difficult in most cases unless you are running a stove hot. In general, using less wood (limit wood) and more air will keep the glass cleaner.

It would be great if it was always perfectly clear but I understand this is a heating machine and not a fashion show. I just want to make sure my dirty window isn't the symptom of another issue and it doesn't sound like it is.

The stove spends most of its time between 300-500. Since I have a strong draft and no further "turn down" running full closed from reload, I have been careful with it so far. One load that I let char on reload ran up to 620 and had me a little nervous. I think I may put in a pipe damper so that I have some control at the top end and then begin experimenting with running the stove from 450-625 or so.

Brick (ware)House · Jan 1, 2014

fire_man said:
Keeping the glass clean on the PH has been more of a challenge than I remember from the FV. My wood is definitely seasoned 3+ years so it's not the wood. The funny thing is the glass seems to have developed a permanent hazy etch that is very difficult to remove.

That doesn't sound awesome. I can get mine perfectly clear (it's less than a month old) but it takes a cold stove and elbow grease to do it. What is weird is that the little part of the window that is arched at the top is always completely clean and the gunk starts in a straight line across where the top of the cast sides are. Basically after a few burns I have a perfect square of the window that is dirty and then a little arched section at the top that is totally clean. Can you understand what I am explaining without a picture? Does this happen with your stove? Any ideas why?

binko · Jan 1, 2014

I am into my 3rd season with the PH and insist on clean glass.
I find that I can go approx 5-7 days with the glass acceptably clear (clear enough to read newspaper print thru it).
My glass will dirty up if I have the air turned down too low. As long as the air control is open approx 3/8th inch or more from the closed position, I keep clean glass and no back puffing.

Berner · Jan 1, 2014

First season on the PH but I' have been pretty impressed with how clear the glass is. I do get that haze line running horizontally that you were talking about. Mine starts up high and as the load burns down the haze line comes down with it. Then when I get up from the overnight burn it's gone.

During the first few weeks with the break in fires and being timid on how hard to run the stove I did get some pretty cloudy glass. Using warm water and 0000 steel wool worked wonders on cleaning off the haze. Just make sure the glass is cold, wipe it gently with wet steel wool and run a paper towel over it to dry. This leaves my glass looking like new.

I haven't had any success burning off the haze with a hot fire. The hot fire maintains a nice clean glass but won't clean anything that was previously there.

semipro · Jan 1, 2014

Brick (ware)House said:
Wood is elm that was bark off, standing dead cut and split late summer. Looks and feels thoroughly dry.

There's a good chance your wood is not as dry as you think it is. Invest in a moisture meter, split a piece of wood and check the fresh face with the meter. 20% or lower is what you're shooting for.

Berner · Jan 1, 2014

semipro said:
There's a good chance your wood is not as dry as you think it is. Invest in a moisture meter, split a piece of wood and check the fresh face with the meter. 20% or lower is what you're shooting for.

How hard do you depress your moisture meter into the fresh cut split? My MC will change upwards of 5% from where I initially depress the prongs to if I put all my weight on them. Obviously the harder I press the higher the MC. Makes it kind of difficult to read your MC consistently.

toddnic · Jan 1, 2014

My guess would be that you have wet wood. Burning wet wood or starting the stove when it is cold (shoulder season) can cause the glass to fog. Mine stays fairly clear as long as I am burning 24/7.

semipro · Jan 1, 2014

Berner said:
How hard do you depress your moisture meter into the fresh cut split? My MC will change upwards of 5% from where I initially depress the prongs to if I put all my weight on them. Obviously the harder I press the higher the MC. Makes it kind of difficult to read your MC consistently.

I believe this depends on the specific meter. I shoot for about 3/8" to 1/2" penetration.
I think others here may know better than me.

Edit: I'd be surprised if this isn't covered by a sticky here. If it isn't it should be.

Edit2: maybe this sticky covers it: https://www.hearth.com/talk/threads/using-a-multimeter-to-measure-wood-moisture-level.40033/

Brick (ware)House · Jan 1, 2014

Berner said:
First season on the PH but I' have been pretty impressed with how clear the glass is. I do get that haze line running horizontally that you were talking about. Mine starts up high and as the load burns down the haze line comes down with it. Then when I get up from the overnight burn it's gone.

During the first few weeks with the break in fires and being timid on how hard to run the stove I did get some pretty cloudy glass. Using warm water and 0000 steel wool worked wonders on cleaning off the haze. Just make sure the glass is cold, wipe it gently with wet steel wool and run a paper towel over it to dry. This leaves my glass looking like new.

I haven't had any success burning off the haze with a hot fire. The hot fire maintains a nice clean glass but won't clean anything that was previously there.

Thanks Berner. This helps me know what is possible and I won't continue to wonder if I can burn the dirty glass clean. Are you comfortable running the stove up to 650 or so now? What kind of stove top temps do you usually run?

Charles1981 · Jan 1, 2014

is your glass getting a gray ash colored haze or a black haze?

Brick (ware)House · Jan 1, 2014

semipro said:
There's a good chance your wood is not as dry as you think it is. Invest in a moisture meter, split a piece of wood and check the fresh face with the meter. 20% or lower is what you're shooting for.

It may not be bone dry but it can't be too wet because when I reload the lower splits are engulfed in flames by the time I get the last couple on top!

Brick (ware)House · Jan 1, 2014

Charles1981 said:
is your glass getting a gray ash colored haze or a black haze?

Just cloudy and gray haze most of the time. When I load full at night and choke it all the way down there can be some black haze at the bottom where the wood is turning to charcoal but that always burns off during the cycle.

Brick (ware)House · Jan 1, 2014

toddnic said:
My guess would be that you have wet wood. Burning wet wood or starting the stove when it is cold (shoulder season) can cause the glass to fog. Mine stays fairly clear as long as I am burning 24/7.

My guess is that my window is the same as your "fairly clear". I was just curious to know if I should expect it to stay completely transparent or if some fouling was normal.

BrotherBart · Jan 1, 2014

Every modern wood stove uses primary air for the glass airwash. The more primary air, the cleaner the glass. Clamp it all the way down and the glass be gonna get hazy with dry wood and nasty with wet wood.

rideau · Jan 1, 2014

No one has addressed the issue of your red andirons.

You have to have had the stove way hotter than the temps you are mentioning to have had red andirons, and YES, I would be VERY concerned if I saw that in my stove.

If I put a split that has some excessive moisture in it, or if I put in a piece or two of fatwood, I may get some black on my window, but it burns off quickly. I do not have to clean my window. It cleans itself, and the inside of my stove is light gray throughout. I burn at around 400 stovetop most of the time. Maybe 450 if I have a good load of wood.

-20 F and I am trying to get a lot of heat quickly, maybe 500, but that is unusual.

My glass stays very clear.

Brick (ware)House · Jan 1, 2014

BrotherBart said:
Every modern wood stove uses primary air for the glass airwash. The more primary air, the cleaner the glass. Clamp it all the way down and the glass be gonna get hazy with dry wood and nasty with wet wood.

That's exactly what I was looking for. My setup seems to like to run full closed with no smoke out the stack so I will just clean the glass every few weeks until I put in a pipe damper. Thanks.

Berner · Jan 1, 2014

Brick (ware)House said:
Thanks Berner. This helps me know what is possible and I won't continue to wonder if I can burn the dirty glass clean. Are you comfortable running the stove up to 650 or so now? What kind of stove top temps do you usually run?

Right now I'm in a cold snap. Definitely the coldest it has been all season. The highest I've had this stove up to is 575. Typically my loads peak around 500. However when the temps are up to 40's during the day I run the stove around 400. If it went higher it would be 80 plus in the house which is too much for me.

Clean glass is a tough thing to measure. I would consider it clean but there are some ash deposits on the glass. These don't bother me because I know they can come off with the paint brush clean or the steel wool if needed. The dark haze I got during the first few weeks with the stove really bothered me which is when I would consider the glass dirty.

Maybe Hearth.com should come up with a glass clarity scale?

Brick (ware)House · Jan 1, 2014

rideau said:
No one has addressed the issue of your red andirons.

You have to have had the stove way hotter than the temps you are mentioning to have had red andirons, and YES, I would be VERY concerned if I saw that in my stove.

If I put a split that has some excessive moisture in it, or if I put in a piece or two of fatwood, I may get some black on my window, but it burns off quickly. I do not have to clean my window. It cleans itself, and the inside of my stove is light gray throughout. I burn at around 400 stovetop most of the time. Maybe 450 if I have a good load of wood.

-20 F and I am trying to get a lot of heat quickly, maybe 500, but that is unusual.

My glass stays very clear.

I have had the andirons glowing once when doing the tail end of my burn in fires when I wanted to push the top cast to just shy of 600 to cure the paint and one other time when I loaded almost full and followed the normal advice to char the wood for 10 minutes or so before closing down. That load put the top cast peak at 620 and the stone on the bottom front at just over 600. I learned right away that with my draft I need to close down almost immediately to prevent the whole box from going off at once.

I do need lots of heat and was hoping to eventually fine tune so that I could run up between 500-600 or so. That would leave 100 degrees below the recommended not to exceed temperature of 700. Is there a problem with running the stove up around 600 degrees? I don't want to damage the stove but I bought a Cadillac and want to run it like one!

Is there a technique for running at higher temps without having the andirons get hot enough to glow?

rideau · Jan 1, 2014

I think you should call and talk with Woodstock.

I really think your stove was well over 600 if your andirons were glowing. And that is way hot to have a stove in the early goings when you are curing the paint.

When you start with a load of wood, if you have a really strong draft as you seem to have, I would only open the air a little over half way. You should not have any smoke in the stove at this point, so should have no issue with seepage of smoke. As the wood engages, slowly lower the air, aiming to keep the stove from roaring. You needn't shut the air completely, all at once. Just slowly close as the fire builds, as I said avoiding a roaring draft. With this cold weather and a tall flue, I would expect you can burn with the air almost totally closed without any issue of backpuffing. I'd dial the air down as the fire builds, and once totally closed, would then just crack it open....1/14 of an inch or so...just to play safe re backpuffing. If you see robust secondaries even with the air just cracked open, then I would close the air all the way and watch the fire for a few minutes. If it keeps burning, doesn't go black, then you are probably fine with the air all the way closed.

I'd be really careful to not get that stove as hot as you have had it. You are better to put more wood in and burn at a lower temp to get more heat, than to plan on pushing that stove over 600 all the time. The stove puts out a tremendous amount of heat way under that temp, and, again, you have had the stove over 600 if your andirons have been red..

Red twice, on a new stove, as you have reported, I'd be checking very carefully for damage. Especially if you are seeing visible smoke. I don't recall anyone with the original smoke smell issue seeing visible smoke, AND that issue has been resolved. So I would be concerned that something else is going on in your situation.

How do I keep PH glass clean?

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