Mike from Athens said:
I have been lacking that consistency that engineers such as myself need in life to avoid all sorts of internal and external turmoil. I have been losing sleep thinking about all of the different factors contributing to the inconsistent performance of my stove, and have not been able to make any sense of it.
Haha, I actually know exactly what you are talking about! I think we have a lot in common. I also agree that the CFM techs (not to mention the owner's manual) are not always that helpful. I was a little ticked off when I first read in the user's manual (page 19 under the heading "Successful Wood Burning") "Woodburning is often said to be more of an art than a science." I thought, come on, that's ridiculous, tell me what the variables are and lets turn this into all science. Part of me still feels that way, but experience shows that there are an awful lot of variables (species of wood, size & shape of wood, configuration and orientation of wood, quantity of wood, moisture level of wood, climate, outdoor temperature, outdoor and indoor air pressure, humidity, flue and chimney configuration, flue and chimney materials, flue height, chimney height, type of chimney cap, blockage in chimney, management of coals, management of ash, thermal mass, and I'm sure I missed at least a dozen other factors).
I'm still trying to learn a few things myself, the most important of which is what is the best way to quickly produce a large bed of lasting red hot coals. Every species of wood has different coaling properties, this is the #1 factor in the variability as it relates to operating this stove. Other factors for creating that initial coal bed include the size of the pieces of wood you initially use and how the pieces are placed. These are all things I'm still experimenting with and learning about. It seems that placing the wood perpendicular to the front door could make it burn slightly faster and hotter due to the flow of air from front to back or top but you can only place small lengths in that direction. Small splits obviously will burn faster and hotter because of the increased surface area.
At any rate, the key to a good burn is to first get a really big red hot bed of coals - and again, the more input on the best way to do this the better - but most will just put a big pile of small splits in there with a bunch of kindling and let it completely burn down to coals, which could take an hour or longer, and of course the bypass is open during this period. Once you have your coals, you are going to use a shovel or other tool to push them all towards the center/back of the stove, its OK if coals go into the "throat". Then you pile on some fresh splits, smaller stuff first, big stuff on the top, and let it catch fire. This is when you want to start paying attention to temps. I think a probe flue thermometer is the best way to measure temps, everything else is inaccurate but as long as you measure consistently you should be able to compensate. All my temps are internal flue temps (your external numbers might be as much as half of my flue temp readings). I've revised my opinion here a couple of times but I now believe you want to see the new wood pretty much engulfed in flame with a flue temp of at least 700 and probably better at 800 before closing the bypass (I wouldn't rule out going up to 1000). This might take 20 minutes or longer if you do it by the book, or about 3 minutes if you crack the ash pan door (which probably voids your warrantee
). Whatever you do, do NOT leave the stove unattended with the ash pan door open.
At this point you close the bypass and you will hear the everburn rumble (the giant sucking sound as Ross Perot would say). Sometimes after things settle down its quiet enough that you might have to go around back and listen right near the air inlet flange.
This is another point where you will see a lot of variability, and I think it is mostly related to the quality and type of wood you are burning. If all is well (dry wood) the stove should go "thermonuclear" with the everburn rumble sustaining itself for as long as the new wood has not burned down to coals. Sometimes there is a delay, where the everburn dies down but returns with passion after some time (could even be hours later as a thicker bed of coals is established or more wood catches fire).
Continuous temps of up to 900 are not impossible, but 600-800 is more typical. Sometimes the temps will go down as low as 500 especially as the wood is well consumed but I don't think I've ever heard an everburn going at temps below 500. As Elk said in this thread "things in motion tend to stay in motion; you get a good secondary burn it tends to continue" - this is true. Once you get a good secondary burn its hard to ruin it, you can add wood and damper down almost immediately. If the secondary burn is not so good, when adding wood you should push ash away from the throat opening in the back and move fresh coals over. You also don't want to just toss a huge split right onto your bed of coals. I find it works better if you can add wood before things have completely burned down to coals, otherwise you need to build things back up with small splits in first and a pause before dampering down.
Recently I accidentally made a red hot coal tunnel to the throat opening which produced fantastic results (basically red hot coals on the bottom and a red hot split of coaling wood that was above the throat opening so all exhaust had to pass though this "coal tunnel"). I think this is another case where "art" is involved - sculpting those coals for an ideal secondary burn, which is any configuration where the exhaust is forced though red hot coals before it hits the secondary burn chamber.
