Pipe Damper Usage -- what's up ??

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jimmyb7

New Member
Jan 21, 2012
57
NS Canada
Hey all !

Been enjoying my Osburn 2400 EPA Stove !
Thanks for all the helps in replacing the problematic VC stove.

I'm getting 8-10 hour burns - can even forget to get up and still have coal to easily get a fire going hours later. This is really good.

HOWEVER --- Really cold nights or strong wind really gets my draft going. And sometimes if the wood needs a little longer to really catch, sometimes the firing gets really strong and a load of wood can be coals in 3 hours.

I'm talking about Strong Secondary Firing.

So---- on the assumption cutting more air off from getting into the secondary pipes would PROLONG the burn time (even if sacrificing some temp)..... we decided to get a Pipe Damper installed (professionally). It's inserted about 14 inches above the stove top (double walled pipe)

HERES THE STRANGE THING: Closing the damper to 3/4 or a little better OFF actually added 50-75C to the temps and Increased Secondary Firing, and seems to shorten burn time. (and this is always with the front air turned off).

What's up with that? Even the store thought the Damper would restrict the updraft and thus the the Secondary firing--- It's the secondary firing we are trying to minimize.

Thoughts? So we thought, ok, the closed damper is causing more heat to be kept in the stove, increasing the stove Temp and so making the wood burn down faster. But restricted air should reduce the Secondary Firing, but it increased. Not just higher inside temps.

How can this be working backwards ????

Anyone ?

Thanks
 
NOTE: Forgot to say..... This is after I load up some wood on a bed of coal. I have about 4-5 split and round (maybe about 35% full load) I do the gradual bottom air cut back til closed. Temp is going about 400-450 and then shut close to off the Pipe Damper. Up it jumps.

WELL..... about an hour later, there is nearly no flame at all and the temp has dropped from 500-525 down to 400. We have wood shaped coal.

Burns up faster and the temp drops BUT THE WOOD ALSO STOPS BURNING FURTHER..... I mean it's almost like the fire then decides ok, we've burned to wood shaped coal, now lets stop all together.

ALSO ---If it burns up well, I check in the morning, if everything seems to be ash and a little coal ---- the BACK OF THE STOVE STILL has a solid shape of black coal almost like wood.

I know.... too much info -- I just have no clue.
 
Correct me if I'm wrong, but I think it would do this;
Closing the damper (too far) would create more smoke. This would burn off while hot, (more secondary combustion fuel) so I would imagine you would see an increase at first, (during that first hour) then the restriction would slow down combustion (choke entirely) until temps drop enough to lose all combustion ? Try maybe 1/4 closed or less? It may not take much.
 
Damper professionally installed 14" above the stove? How did they do it, and what brand of dwp are you using? All damper's I have seen so far come as a component with it's own piece of pipe.
 
KodiakII said:
Damper professionally installed 14" above the stove? How did they do it, and what brand of dwp are you using? All damper's I have seen so far come as a component with it's own piece of pipe.
Click to expand...
Most of the dampers I have ever seen you have to drill your own hole on both sides of the stove pipe and install.
 
wkpoor said:
Most of the dampers I have ever seen you have to drill your own hole on both sides of the stove pipe and install.
Click to expand...

On double wall. It is bought as a Stove adapter. Only has one hole externally. The opposite side of the handle (turn key) has no hole and is solid pipe.

For single wall you drill a hole in both sides and install.

Im sure it could be done with double wall. But most are bought and its the 1st section of pipe.

To the OP- The damper will try and slow overall draft. But the secondary air is unregulated. So by closing it down farther and keeping more heat within the stove, the secondaries are going to have more fuel (smoke) to eat (what Coaly said above).

To go from 10 hrs to 3 hrs is just crazy. Has anything else changed? Wood supply? Etc? That just seems like a HUGE difference in time.

I have one installed and have used a couple times. But never closed more than half-way and the only other time used was an overfire (oops).
damper.jpg
 
It sounds exactly how you make charcoal......o_O
 
BTW a tip for those that have single wall. To get the holes perfectly lined up I wrapped a piece of paper around the pipe and marked it for length. Then remove paper and measure for halfway point. Reinstall paper and mark or center punch. Holes will be perfectly across from each other and damper will center in the pipe.
 
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Closing your damper will make the stove hotter but the flu cooler. Dampen down sooner based on flu temp/ I get my flu up to 450+ then start my air closing. increase the amount you shut the air till the flu stabilizes.

This is what i do on my nc13 in the basement with 28+' pipe and i relight with coals every morn. Glass is clean and less than a coffee can of soot i also have a pipe damper..
My secondary the air in the stove is on fire not the wood lol.

See here
 
Secondary air is driven by the flue just like primary is. Close the damper and you slow down the pull for both of them. As to damper sections for single wall pipe they are readily available. Just not as cheap as the four buck jobbie where you drill your own holes and put a couple of leaks in your connector pipe.
 
Jimmy, you ask why the stove operates better when you close the damper 3/4 ways?

Most likely your draft is a little strong, these newer type non-cat stoves its all about the heat build up in the stove to get into and maintain the operational temperature range for secondary burn. The way to look at it is that extra air coming in is a cooling effect on the temps in the stove. Its a hard concept to grasp, that most people think more air means more burning and more burning should mean more heat. But alot of times "at your low burn rate settings" if the draft is too strong your flushing heat up the chimney and cooling your firebox. On the other hand adjusting your damper just perfect allows the heat to build hotter lets the wood burn slower and the extra heat gets the smoke gases burning better or maybe could say easier. Its all a happy mix. I work for a major engine manufacturer and they are tuning to get cleanest burns also and they call it the recipe. Recipe as all the variables involved in the perfect tune for cleanest burn for lower emissions.
 
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