Is the liner supposed to be clean at the top and dirty on the bottom?

TedyOH · Oct 13, 2015

Hi Everyone,

I've been burning wood in an open fireplace for 25 years, decided to put an insert in last year, a Pacific Energy Neo 2.5. I did my first liner sweep, the top of the liner was spotless, just a slight brownish "smoke cured" look to it, but at the bottom, inside the insert, it was filthy (see picture). Does this look and sound normal? The "soot / powder" I removed from the bottom was quite a bit I thought, maybe enough to fill a half gallon milk container. Very powdery and had a metallic gleam to it, no tar or sticky sap like gunk. I decided not to insulate the liner as the chimney is only exposed 10' to the exterior (2 story colonial). The chimney is partially inside the garage then above the garage in attic space, then exposed the final 10 feet. I have no problems drafting when lighting a fire.

Thanks in advance for your thoughts.....

mellow · Oct 13, 2015

Mine has more at the top due to the temps cooling as it goes up, not much but still more than at the bottom. Could something be cooling the pipe or introducing air at the bottom?

jatoxico · Oct 13, 2015

I wouldn't say supposed. Ideally it's supposed to clean throughout. The pic you show does not look too bad for the bottom but they all look like that more or less. The creosote you got sounds like stage 2. Black shiny crunchy. Want as much brown fine as possible.

Now what you may have encountered is that the gases go up hot then hit a cool zone in the system where a significant amount of flue gases condense. As you brush you hit that spot and it's extra dirty. No doubt it's where the gases are condensing. May have a zone that occurs at start-up that eventually warms then another that occurs during your operation.

You say the system is new to you. You may be able to improve what you're getting by changing your habits as far as how you burn the unit and improving the quality of the wood. You may need to do some insulating in the smoke shelf and add a block-off plate. Many things to consider.

Do you do a lot of cold starts?
Is the wood dry (<20%)?
Do you shut the air down all the way?
Are you using a stove top thermo to monitor temps?

GS7 · Oct 13, 2015

TedyOH said:
Hi Everyone,

I've been burning wood in an open fireplace for 25 years, decided to put an insert in last year, a Pacific Energy Neo 2.5. I did my first liner sweep, the top of the liner was spotless, just a slight brownish "smoke cured" look to it, but at the bottom, inside the insert, it was filthy (see picture). Does this look and sound normal? The "soot / powder" I removed from the bottom was quite a bit I thought, maybe enough to fill a half gallon milk container. Very powdery and had a metallic gleam to it, no tar or sticky sap like gunk. I decided not to insulate the liner as the chimney is only exposed 10' to the exterior (2 story colonial). The chimney is partially inside the garage then above the garage in attic space, then exposed the final 10 feet. I have no problems drafting when lighting a fire.

Thanks in advance for your thoughts.....

View attachment 163692

Looks like mine did before I cleaned it. The black powdery stuff came off easily. This is as far as I could see with this flashlight looking down from the top. Bottom up view looked just as clean when I was done.

TedyOH · Oct 13, 2015

mellow said:
Mine has more at the top due to the temps cooling as it goes up, not much but still more than at the bottom. Could something be cooling the pipe or introducing air at the bottom?

I don't think so - for what it's worth before I installed the box in February (liner was installed), I lit a piece of paper on fire to see if I was getting a down draft from the space around the tile and liner, all seemed good.

TedyOH · Oct 13, 2015

jatoxico said:
I wouldn't say supposed. Ideally it's supposed to clean throughout. The pic you show does not look too bad for the bottom but they all look like that more or less. The creosote you got sounds like stage 2. Black shiny crunchy. Want as much brown fine as possible.

Now what you may have encountered is that the gases go up hot then hit a cool zone in the system where a significant amount of flue gases condense. As you brush you hit that spot and it's extra dirty. No doubt it's where the gases are condensing. May have a zone that occurs at start-up that eventually warms then another that occurs during your operation.

You say the system is new to you. You may be able to improve what you're getting by changing your habits as far as how you burn the unit and improving the quality of the wood. You may need to do some insulating in the smoke shelf and add a block-off plate. Many things to consider.

Do you do a lot of cold starts?
Is the wood dry (<20%)?
Do you shut the air down all the way?
Are you using a stove top thermo to monitor temps?

Insulation and the block-off plate are definitely considerations, I was reading the other threads on those topics.

Cold start, meaning the no action in the box for a few days? Not really, especially with last years temperatures.
Dry Wood, I assumed so, bought a Moisture Meter for this year to be sure. Never much black on the glass, more whitish stuff in the corners sometimes.
I definitely chocked the air down, all the way down at night when I went to bed.
Nothing to monitor temps, do you have a manufacturer you could recommend?

I am going to try to run it wide open with the first box load of wood this year to get a good bed of coals, I think the manual says to do this and I've read elsewhere others do this.

Thanks for the responses....

TedyOH · Oct 13, 2015

GS7 said:
Looks like mine did before I cleaned it. The black powdery stuff came off easily. This is as far as I could see with this flashlight looking down from the top. Bottom up view looked just as clean when I was done.

x2

jatoxico · Oct 13, 2015

Condar thermos are liked. I have a Rutland, it works. Try to find a spot that you think will give you a read of the top temp. Run >450 or so as much as possible. 650 is fine. I back off after that but have hit higher. No glowing or whitish paint indicating over-fire. My sweet spot is 575-625 peak. Cooler as the load burns down is OK since most creosote forming gases are gone during coal stage.

Cold starts = having to use paper etc to start up. Means chimney has probably gone, for all intents and purposes, cold.

TedyOH · Oct 13, 2015

jatoxico said:
Condar thermos are liked. I have a Rutland, it works. Try to find a spot that you think will give you a read of the top temp. Run >450 or so as much as possible. 650 is fine. I back off after that but have hit higher. No glowing or whitish paint indicating over-fire. My sweet spot is 575-625 peak. Cooler as the load burns down is OK since most creosote forming gases are gone during coal stage.

Cold starts = having to use paper etc to start up. Means chimney has probably gone, for all intents and purposes, cold.

This insert is a flush mount insert, I'd have to remove the surround the get a reading off of the box, unless you think the top of the door is a good spot?

Unfortunately, my firebox is only 2.5 sq/ft so I have to empty the ashes (hot coals) about every other day so I do have a lot of cold starts.

I was an inch short on depth for the next larger size insert (not the first time or situation where I've had this issue)

jatoxico · Oct 13, 2015

TedyOH said:
This insert is a flush mount insert, I'd have to remove the surround the get a reading off of the box, unless you think the top of the door is a good spot?

Unfortunately, my firebox is only 2.5 sq/ft so I have to empty the ashes (hot coals) about every other day so I do have a lot of cold starts.

I was an inch short on depth for the next larger size insert (not the first time or situation where I've had this issue)

I have a flush mount, stick it in the vent a few inches back towards the center by the flue. I point mine so that when needle is pointed straight toward front it's at 500. Sometimes I use a small flashlight if I need to see exactly what temp it is. Could also get an IR thermo. They are cheap and can also tell you how hot the dog or cat is while chasing the light.

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Is the liner supposed to be clean at the top and dirty on the bottom?

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