Damper clogging

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.

CT Erik G

New Member
Mar 6, 2021
Hello Folks!!

I have a 1970's Huntsman 241 wood burning stove attached to a 7x7 clay flue lined brick chimney that is 37ft tall.
The stove sits about 3 feet from the base of the chimney in my basement.
From the back of the stove I have a 6" 90 shaped to a 45 into a Dura black damper then 6' straight pipe to a 90 into the chimney near ceiling height.
Day burn stove temps are between 400-600 degrees, heat stat in Pic's above damper 12" above top of stove reads 400-500 normally, overnight dampened to burn 7-10 hours pipe temp is between 200-300 degrees. Unless my loving wife lets it go down during the day when I'm not home :( we tend to burn hot to heat 3 floors in a 3k SF house.

I have a moisture meter and the wood (Oak- Walnut) ranges from 10-20% on split two year seasoned and sheltered since Sept in a wood shed.

Attached pic's: Cleanout shows the chimney creosote knocked down from a quick clean just now while the stove pipe was being cleared and I have very very little debris as you can see. This chimney was cleaned professionally 3 months ago along with the pipe. I also cleaned the 6" between stove/chimney twice once I started burning in Nov. I have burned approx 1/2-3/4 cord so far.

The reason I had to clean it, is due to the throat damper shown in Pic's getting clogged not allowing it to close completely and or blocking exit gasses causing pipe and front regulators to smoke. I use Anti-Creo-Soot often as directed.

When having to clean the damper section I see the center holes completely block the first time and almost block this time and a ring of debris clogging the space between the plate and pipe so when you try to close the damper it completely seals the pipe like an HVAC damper backing smoke into the house.
Pic's show stat temp while bringing the stove back online after cleaning.

This is the first year it has done this to this extent, is this common? Hope I answered any questions in advance, I searched for a related issue prior!

Any help would be Much Appreciated!!


20211211_164657.jpg 20211211_164708.jpg 20211211_164842.jpg
Did you measure the moisture content on a newly split surface?
Hm, I'm asking because the shiny deposits are the worst kind. And they appear most often when the wood is too wet. Or when the fire is choked down too much and/or too soon.

I would consider adding a (insulated) stainless liner.in your chimney.

@bholler is the expert and likely can help better than me.
We need more info to figure out what going on but obviously it's bad and could be quite dangerous. Re check moisture content. Move the thermometer further up the pipe make sure the clean out is sealed well.
Like bholler said, you probably need to move that magnetic thermometer up a bit. I interpret 12-18" above the stove top to be the vertical distance, not the diagonal distance along the pipe. So, get a ruler, stand it vertically on the stove top, then use a level to transfer your desired distance to the stove pipe. That's where the thermometer goes. You are probably not running this stove up to the temperatures that you think you are and that can result in creosote accumulation.

How old is the stove pipe in that picture? Has it been fired? Every time I have ever used single wall, it starts out shiny but it turns flat black after it gets fired to operating temperatures. Oh yeah, and it gives off some stinky paint fumes while it is doing it. Now, that could just the brand I used. Maybe you have the good stuff :). But to me, that stove pipe looks like it hasn't really been fired very hot.

It doesn't look like you have the clearance you need to combustibles. For stove pipe, that is 18" for single wall, and you can reduce that to 6" with double wall or properly installed shielding.

If you get up to temperature, that wood looks like it will get a little too hot. If that creosote you have accumulating ever does light up in the stove pipe, the stove pipe will glow and you could have the wood in the picture on fire.

yes what is said above. take you temp on the pipe and bring it up to 350. that might mean that you don't close the pipe damper all the way. that used to happen to me in another house and setup. i could only close the damper 3/4 to 7/8ths closed. the damper is mostly designed to slow a big draft from a tall chimney
Have you considered making and installing a baffle plate inside the stove? this will create hotter firebox temps and possibly reburn the soot / creosote particles which are jamming you up.
Have you considered making and installing a baffle plate inside the stove? this will create hotter firebox temps and possibly reburn the soot / creosote particles which are jamming you up.
It already has one, from what the manual says. I was curious about this stove, so I looked it up a couple of days ago.

It seems like it would work better if the smoke had to come forward toward the top air inlet to get out, rather than having it go backward and snake around where there are no air inlets.

  • Like
Reactions: kennyp2339