Light gray spots in firebox of insert after some burns... overfire or something else?

[bens_igloo]

It's been a 2 or 3 times now this winter where I'll wake up in the morning and there are some light gray patches on the inside of my Regency 2400 insert. On the next burn they disappear and turn back to normal dark brown/black.

From what I've heard here before this is a sign of overfiring. However I always wait for the stove to cruise steady before going to bed - meaning good secondaries, front thermometer above door steady at around 550-575, air mostly closed down. The glass on the door seems to get the same light gray film that I need a wet paper towel to wipe off.

I've never seen any part of the stove glow except the secondary air tubes and sometimes parts of the ceramic board baffle.

Am I overfiring my stove or am I just being overcautious?

 

[Typ0]

looks like ash to me.

 

[BobUrban]

just ash. One split was facing a certain direction or the load was such that a vortex tunnel was created continuously spewing spent fuel in that spot. Next burn, different configuration = gone. Nothing to worry about.

 

[kennyp2339]

I'd be more concerned about the dark / black spots, those spots mean your firebox is not getting hot enough. It could be from running the stove to low, or not that good of a wood supply. In any case on an epa stove (exclude cat) the firebox should be the hottest part of the whole system, if your getting black creosote in the firebox, imagine what the chimney looks like.

 

[bens_igloo]

I'd be more concerned about the dark / black spots, those spots mean your firebox is not getting hot enough. It could be from running the stove to low, or not that good of a wood supply. In any case on an epa stove (exclude cat) the firebox should be the hottest part of the whole system, if your getting black creosote in the firebox, imagine what the chimney looks like.

Interesting comment.. to me it looks a lot like the firebox of other burners on the site. I have no reason to doubt either my operating temps or wood supply - the stove is always running at 450-600 measured on the front of the stove (so 550-700 approx stove top temp). Likewise wood is all 2-3 year maple and ash measuring under 16 percent on fresh splits. After sweeping last season I got about 3-4 cups worth, no more.

 

[Supersurvey]

Interesting comment.. to me it looks a lot like the firebox of other burners on the site. I have no reason to doubt either my operating temps or wood supply - the stove is always running at 450-600 measured on the front of the stove (so 550-700 approx stove top temp). Likewise wood is all 2-3 year maple and ash measuring under 16 percent on fresh splits. After sweeping last season I got about 3-4 cups worth, no more.

I have a Hampton HI200 insert and also all exposed steel is black. Fire bricks white and glass stays mostly clean or easy to clean. About 3 cups of creosote after 1.5 years. Don't know how to keep steel white. Any Adela's?

 

[Typ0]

That black looks caused by the air flow. You might want to look at the firebrick configuration.

 

[Jo191145]

Umn I run a cat stove and the entire firebox is grey except for an occasional chunk of coaling wood not quite burnt up yet. If it was black I'd be worried.

 

[bens_igloo]

This all has me pretty curious. My firebrick configuration is OK and my fires burning nice and hot.

Anyone with a 2400 care to show a picture of the inside of their firebox?

 

[kennyp2339]

Do the dollar bill test on your door seal, FYI your fire box looks fine on the pic

 

[bens_igloo]

I did a couple months ago with no issues but will check again.. you never know.

 

[jatoxico]

I don't have that unit but my firebox and brick looks more "grey" (firebrick light tan) than dark brown black. Off hand I'd burn with more air and hotter. Maybe its just the angle of the picture but I'd be shooting to make the whole firebox look like that "grey". Have to clean the glass much?

 

[bens_igloo]

I don't have that unit but my firebox and brick looks more "grey" (firebrick light tan) than dark brown black. Off hand I'd burn with more air and hotter. Maybe its just the angle of the picture but I'd be shooting to make the whole firebox look like that "grey". Have to clean the glass much?

Rarely ever have to clean the glass. My firebricks always end up white after a burn, it's just the steel that stays dark.

 

[jatoxico]

Rarely ever have to clean the glass. My firebricks always end up white after a burn, it's just the steel that stays dark.

Must just be some cool spots, I get small dark patches in the very corners of the firebox up by the door. If the liner is staying clean and the glass isn't too dirty you must be doing something right. Maybe you could add a smidge more air especially overnight if you're doing that. Tough balance, long burn also usually means slightly dirtier burn too.

 

[prezes13]

In my opinion you run your insert hot. My insert never got up to 500 above the door, but that's with a blower on.

 

[midwestcoast]

Hmm, those temps do sound a tad hi to me, but it's a tough stove to compare temps on as there's no great spot for a thermo. You have yours in about the best spot possible IMO. I also find the thermo vs inner box temps vary significantly with blower use. Do you normally run with fan on Low or Hi?
550-575 with fan on hi is quite hot for this stove.
I'd say it is possible to have an over fire of the box with a reading of 575 on the thermo, especially on a quick start-up or reload.
Another way to check is: When it's running at/near the highest temps you normally see, shut off all lights & look under the top shelf into the blower air vent space. The inner steel box is exposed in there & it's a hot spot. If all black in there, you know the inner box is at least below ~900 . If you can see any faint red, the inner box is somewhere around 1000-1200. If it's cherry red, more like 13-1400 range .

Mine is feisty with ~27' of liner straight up & dry wood. I blocked off my EPA hole as a hedge against run-aways.
I do occasionally see faint, dull red below the shelf before the thermo would indicate any issue. My burn tubes & front lip of the baffle often glow also. I feel I'm pushing my stove a bit burning like this, but no issues yet.

One more thing, it looks like you may have your 2 piece baffle pushed tightly together & not butted tight to the outside edges. If so push the 2 pieces apart & the rabbet joint will still overlap somewhat in center. Make sure it's pushed all the way back as well.

 

[bens_igloo]

Hmm, those temps do sound a tad hi to me, but it's a tough stove to compare temps on as there's no great spot for a thermo. You have yours in about the best spot possible IMO. I also find the thermo vs inner box temps vary significantly with blower use. Do you normally run with fan on Low or Hi?
550-575 with fan on hi is quite hot for this stove.
I'd say it is possible to have an over fire of the box with a reading of 575 on the thermo, especially on a quick start-up or reload.
Another way to check is: When it's running at/near the highest temps you normally see, shut off all lights & look under the top shelf into the blower air vent space. The inner steel box is exposed in there & it's a hot spot. If all black in there, you know the inner box is at least below ~900 . If you can see any faint red, the inner box is somewhere around 1000-1200. If it's cherry red, more like 13-1400 range .

Mine is feisty with ~27' of liner straight up & dry wood. I blocked off my EPA hole as a hedge against run-aways.
I do occasionally see faint, dull red below the shelf before the thermo would indicate any issue. My burn tubes & front lip of the baffle often glow also. I feel I'm pushing my stove a bit burning like this, but no issues yet.

One more thing, it looks like you may have your 2 piece baffle pushed tightly together & not butted tight to the outside edges. If so push the 2 pieces apart & the rabbet joint will still overlap somewhat in center. Make sure it's pushed all the way back as well.

These are some great guidelines, thanks! Those temps are with the blower on low (I rarely use high).

I'm going to check under the connection chamber with the lights off.

 

[prezes13]

I think you are hot I think stove top is about 200 degrees higher than what you read with your thermo in that spot.

 

[rdust]

I remember making posts like this when I bought my first stove.

Enjoy the stove I'm sure you're doing fine.

 

[Supersurvey]

It's been a 2 or 3 times now this winter where I'll wake up in the morning and there are some light gray patches on the inside of my Regency 2400 insert. On the next burn they disappear and turn back to normal dark brown/black.

From what I've heard here before this is a sign of overfiring. However I always wait for the stove to cruise steady before going to bed - meaning good secondaries, front thermometer above door steady at around 550-575, air mostly closed down. The glass on the door seems to get the same light gray film that I need a wet paper towel to wipe off.

I've never seen any part of the stove glow except the secondary air tubes and sometimes parts of the ceramic board baffle.

Am I overfiring my stove or am I just being overcautious?

Can you post a picture of your thermometer placement? I have the HI200 smaller version and am interested in the best place to take temperature.

 

[bens_igloo]

Can you post a picture of your thermometer placement? I have the HI200 smaller version and am interested in the best place to take temperature.

Here's a photo I snapped a few moments ago. That's the best placement and others on the site could find. In this location the thermo is in full contact with the stove body.

 

[Supersurvey]

Here's a photo I snapped a few moments ago. That's the best placement and others on the site could find. In this location the thermo is in full contact with the stove body.

View attachment 154946

I think I have to revaluate my location. I have the thermometer on the metal rib over the glass but not making contact with the insert. I think it's giving more of a glass temperature.