Oxygen-starved stove - drilling out the air intake

17 years ago

Here is one years' worth of trial and error work on a woodstove with a lowish flue temperature ~ 280 degrees at max burn, choked with wood and with the damper fully opened. (Good seasoned hard wood.)

I have an Englander ICD-24 stove that I got almost new and cheap on craigslist in an unfinished basement with an outside air supply in a 1300 square foot home with an outside terracotta-lined masonry chimney, 25' and at regulation height from the peak of the roof. It has never burned hot enough regardless of air supply, type of wood, amount of wood, etc, with or without the catalytic bypass opened or closed, and with the damper fully opened at all times.

Originally I was "over-flued" with a 9x12 chimney, so this year I lined it myself with a SS liner from the chimney store. (By the way, as long as you're not afraid of heights or of chiselling cement/brick, this is a fairly simple thing to do. Cost me $550 for the liner compared to estimates in the range of $2000-3000 for "professional" installation). The idea was that (in addition to supposedly increasing the safety of the set-up) the decreased flue size would increase draft due to less cooling in the chimney. THere was no appreciable difference.

I re-did the outside air supply with left-over 6" liner so that it now goes from a 4x8" window opening through 6" pipe which tapers to 4" at the stove intake. No difference.

I contemplated taking out the catalytic converter to "open up" the exhaust, but decided this would be self-defeating regarding creosote (which is why I'm concerned about the low operating temperatures in the first place), so nix that.

Incidentally, while I like the liner (not sure why, because it's not had any appreciable impact - it's probably just that I'm proud to have installed it myself), the rain cap that is on it now collects condensation and drips on the chimney cap and down the side of the chimney. THis appears to not be creosote, as it's colorless and clear, but it's not helping my masonry any.

So tonight, I got me a 3/8" Cobalt drill bit and drilled 14 holes in the air channel that runs from the intake to the front of the stove. I calculate that this creates about 1.5" square of additional cross sectional area for air draw - an increase of about 12% over the 12.5" square inches from the stock (4" diameter) intake.

This effected a temperature increase of about 10%, so now I'm burning at 320 degrees and it's not even that cold out (I expect it to do better when it's colder).

So for the first time since I've had this stove, there may actually be occasions where I will actually close the damper some. In fact I'm so pleased that I may open the holes to 1/2" with a bigger bit, which would increase the combined cross sectional area of the holes to 2.5" or a 25% increase from baseline.

I'm not sure why this stove is so oxygen starved. Either it's the specifis geometry or other charactistics of my particular set-up, or this stove was designed to be relatively oxygen starved to increase the advertised burn-time. Or it's for the catalytic converter operation, and now I've compromised that, but with my very low operating temperatures and condensation problems, something had to give.

I'm posting this to relate my experience and to see if others have had similar experiences that they would like to share. I'm prepared to hear that I'm crazy for modifying the stove also. BUt I figured that if I created any problem that I would tap the holes and screw in bolts or weld a plate over the holes and I'd be back to where I began...

Thoughts?

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Comments (4)

mountainstoveguy
17 years ago
last modified: 9 years ago
the problem is the basement, not the stove. Stoves dont work well in negative pressure areas, and the air kit must be coming from above the stove, which doenst help either. Heat loss from a stove has a hard time competing with make up air for the basement, which is what your chimney has become. A fresh air intake for the basement.
mountainstoveguy
17 years ago
last modified: 9 years ago
Ohh i started a thread for you on a good wood burner site.
http://www.hearth.com/econtent/index.php/forums/viewthread/5108/
I do think that its crazy that you modded your stove, you have to look at local conditions first, that stove is on the market because it went through extensive testing, and you just voidied that listing, you have to figure it works as designed, and if its not working then there is somthing wrong with the install. if for somereason your burn your house down, and the insurance company finds out you modded the stove your SOL.
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christopherh
17 years ago
last modified: 9 years ago
I wholeheartedly agree with mountainstoveguy. You have just made a good appliance unsafe. Actually, I believe you destroyed your stove.

The very first thing you should have done is called in a professional. They would have told you what to do and saved you a lot of money.
HU-31515019
2 years ago
Great idea. I easily enlarged the intake in my wife's great room stove prior to installation. My basement stove is a little more complicated, but these modern stoves don't allow anywhere near the air necessary for a good fire. Tired of leaving the door open to get enough draft.

I've been burning for 40 years, so the woodstove karens can just save it for somebody else.

Oxygen-starved stove - drilling out the air intake

Comments (4)

mountainstoveguy

mountainstoveguy

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