Dutchwest Non-cat reburner problem

[BurningIsLove]

I've had my new Dutchwest non-cat (large size) up & running for about 2 weeks now, and I'm running into 2 mutually exclusive problems with it. Feel free to suggest on either/both. The flu is rear-exit with about 12" distance from the flu collar to the chimney itself, including the thru-wall connector.

The first problem is after a reload/new fire and getting the reburner to engage. I load up the stove, leave the damper open (reburn chamber off), air input at full, and let the thermometer get up to about 450 degrees. The thermometer is sitting on top of the thru-wall connector for reference. Once up to temp (about 5-10 minutes for an existing fire depending on conditions & wood), I shut the damper to engage the reburner. Most times the reburner engages (there is a characteristic combustion noise and draft noise), the temp rises about 50-100 degrees very quickly, and the visible emmissions at the top of the chimney disappear (nice clean burn). However over the next few minutes, the draft noise stops, the temp drops to about 300 degrees (from about 500), and visible smoke starts coming out of the chimney when the temp drops below about 375. I can crack the ash pan door (not visibly open, just enough to unseat the seal and let in a little extra air). Sometimes this gets everything going, sometimes I have to reopen the damper and start the process all over again, sometimes several times.

The next problem is the reverse once the reburner is operating nicely (no visible emissions), and the thermometer reads about 450. For whatever reason, the temp starts rising rapidly well into the red zone, rising to about 600+ degrees very quickly (just under 2 minutes). I can crank the air inlet all the way down to closed, but that at best lowers the temp to about 525 (still in the red zone). This persists as long as 2+ hours until the fuel inside is reduced to a hot bed of coals. The chimney (masony w/ a clay liner) is so hot to the touch on the outside it will burn your hand.

I've tried adding some less-seasoned wood when re-stocking the stove, but it doesnt seem to have a noticeable impact. If this was an older stove I would suspect the seals need to be replaced, but this stove is nearly right out of the shrink wrap.

Thoughts?

 

[berlin]

Interesting problem, On my single brick-thickness masonry chimney with an 8x8 clay liner i can have sustained flue gas temps of 600*F for hours and the outside of the chimney will be only warm to the touch. You must really be over-firing to have that hot of a chimney.

 

[BurningIsLove]

My chimney is also in a well insultated, non-heated garage sharing the same wall as the stove (opposite sides). So there really isnt much cold, external air to cool the surface down. It takes several hours to get really warm to the touch, and several more to cool down again. It's not like you'd burn your hand even at the hottest temps. Also where I am placing my hand is literally less than a yard away from the flu collar itself, so I would expect it to be relatively hot even under optimal conditions.

 

[got wood?]

Could it be a drafting problem? I've got metalbestos chimneys, so I don't know if masonry needs time to heat up, etc...I was checking out the manual of your stove (http://www.vermontcastings.com/catalog/elements/files/30002291_Dutchwest_NC_Lg.pdf) and on page 27 it claims that masonry chimneys act as `heat sinks' and if the chimney is a large one, it can take a while to heat up and draft properly.

Additionally, there is no mention (that I could find at least) about what temp to engage the reburn chamber. What would be typical for this stove I wonder...

 

[BurningIsLove]

Thanks....it's a medium sized, double-flu masonry chimney w/ a clay liner, maybe a bit taller than average. Neither flu is in operation at the same time, as one is for the oil furnace which never turns on when the stove is burning. There doesnt ever really seem to be much of a drafting problem even when its above 40 degrees F outdoors. The very short stove-chimney connector is very helpful in this regard.

From a cold start, I do let it burn w/o engaging the reburner for at least 20 minutes before trying. It does certainly engage much easier when the stove has been running non-stop for days, but it still is a bit of a pain even when at temperature.

I'm more concerned how easily it overfires when the chimney & stove are at temperature. I havent figured out a way to lower the temperature when the primary air level is completely closed, yet the temp stays consistently about 550 F. Kinda scary sometimes.

 

[elkimmeg]

The next problem is the reverse once the reburner is operating nicely (no visible emissions), and the thermometer reads about 450. For whatever reason, the temp starts rising rapidly well into the red zone, rising to about 600+ degrees very quickly (just under 2 minutes). I can crank the air inlet all the way down to closed, but that at best lowers the temp to about 525 (still in the red zone). This persists as long as 2+ hours until the fuel inside is reduced to a hot bed of coals

Read your manual it is ok to run your stove up to 700 degrees at high burn 525/550 is the perfect range for good heat vollume.
Many thermometers do not reflect the 700 degrees as a safe heating zone. For cat stoves to work by engaging the damper at 550 or 600 is t is best. When Its cold and I need heat I usually do not damper down at all. I control the burn with the inlet air. Your description above describes the optium operation. Get it hot damper it down reduce the inlet air One you have good draft and two your wood must be good and dry.

I load up the stove, leave the damper open (reburn chamber off), air input at full, and let the thermometer get up to about 450 degrees. The thermometer is sitting on top of the thru-wall connector for reference. Once up to temp (about 5-10 minutes for an existing fire depending on conditions & wood), I shut the damper to engage the reburner. Most times the reburner engages (there is a characteristic combustion noise and draft noise), the temp rises about 50-100 degrees very quickly, and the visible emmissions at the top of the chimney disappear (nice clean burn). However over the next few minutes, the draft noise stops, the temp drops to about 300 degrees (from about 500), and visible smoke starts coming out of the chimney when the temp drops below about 375. I can crack the ash pan door (not visibly open, just enough to unseat the seal and let in a little extra air).

5-10 minutes may not be enough time to establish the new wood into the burn cycle. Naturally new wood is going to smoke that is an indication of the early burn stage. What you want to do is control the fire with the inlet air. Forget dampering till it is going correctly. The temp dropping down to 300 and smoke, means that wood has not fully been engulfed. You are still experimenting with a learning curb. You are too quick to damper down,where you should be learning how to reduce inlet air first. You might find that it is best to damper down 1/2 open air feed see where your temp is and make adjustments after 15 minutes. A wood stove is not instant heat or instant opperations, you have to learn a sequence. It is common to here a back rush of air after dampering down. That means your inlet air should be open more before dampering and closed off in 5 minutes or more making adjustments.

I have two VC stoves here and they run similar to yours

 

[BurningIsLove]

Thanks. After a few different methods of re-loading, I have found that it is much "easier" to reload more often, e.g. when the fuel is about half consumed and collapses mostly into a thick bed of coals vs. waiting until it has been more reduced. I've also started adding less wood, not filling the firebox to capacity when reloading. Makes a smaller temp delta between the newly added wood and the coal bed, as well as less time to get the new wood burning completely before closing the damper. Also been letting the temp get up to about 550 vs. 450 before engaging.

Thanks also for the tips on temp. The wall directly above the wall connector is still a little warmer than I would like. I think this summer Im going to remove the single-wall connector and go up to a double wall w/ an internal probe. It's what I had intended on having installed in the first place, but my cheap a$$ contractor installed a single wall connector while I was away for 2 weeks on business.

 

[MountainStoveGuy]

Reading through this thread, some of the answers were givin to you assuming this stove is a cat. Your title states that you have a non cat dutch west. Is that a typo? i didnt know the dutch west came in a non cat version.

 

[BurningIsLove]

Not a typo, they do have a line of non-cat stoves which have very low emmissions (0.8 GPH according to the docs) Here is the link to the one I have:

http://www.vermontcastings.com/catalog/view_product.cfm?ProductId=188

Someone posted the link to the owners manual PDF a few replies above in case you want more specifics. It's an attractive stove (IMHO) and I think once I get to know it a bit better, I will give it very high marks. It has the nice, large glass front that doesnt easily get dirty, and when it does get the occassional soot it burns off soon thereafter. It does suffer from the VC philosophy of no permanent handles. They only supply the one plug in handle which is very fragile (shattered after being dropped only two times from 2 feet). The only level that doesnt need this is the air flow level which gets rather hot after a day of steady operation. But at least the connectors are threaded and you can attach permanent handles which I intend to do shortly.

 

[MountainStoveGuy]

Thanks for clearing that up, im not nearly as confused now. Nice looking stove!