I've been trying to figure out what the difference would be between running the combustion blower continuously vs letting it cycle on and off with the Harman controller. The question being, which gives me the better results (most complete burn, best heat output, etc) I burned for several days with the blower running and collected the ashes in a metal barrel, then did the same with the blower cycling on the controller. I kept everything else the same, feed rate, air intake past the restrictor plate, thermostat setting, pilot timer settings (4 on 12 off), etc.
For my results, I asked a disinterested neutral third party (the D.W.) for an opinion, though I had to explain what I was doing when I called her outside to "feel my ash" the first time
Anyhow, she thinks that there's not much difference in the two barrels- the ashes generally look and feel the same, and when you crush them up, they're pretty identical as far as complete burning goes. As for the fire, there was a big difference- with the blower "on", the stove stayed warmer (350) between cycles, but the fire burned back pretty fast to a skinny orange ribbon that took awhile to build back whenever the thermostat kicked in. In pilot mode, the fire never grew beyond that 1.5-2 inch ribbon. The stovepipe stayed warm the whole time.
On the controller, the stove surface temp fell down to 200 or so and the fire just settled down to a dull orange with some small blue flame but stayed the same physical size as when running. When the timer kicked in, the fire jumped up quickly, less than a minute, and when the thermostat called for heat, the stove came up to normal temps (525-550ish) much much faster. However, I had gotten used to hearing the fan rumble, so when she shut down on pilot mode, the silence kept catching my attention. Also, the stovepipe cooled off to the point where I could keep my hand on it, though when the stoker started up everything seemed to draw just fine.
My overall wondering is I don't want to run that blower all the time if I don't really need to, since what I observed tells me there's not a great advantage. However, is there something I missed or should know about that would change my results? I'm thinking about wear on the grates, having air flowing through all the time like a naturally-aspirated stove as opposed to starving the air and having hot coals cooking them; or the effects of the stack/surface temps rising and falling and so on. Or does this just come down to personal preference, since after 20 minutes or so of good running I can't tell the difference?
Sorry so long, never thought monkeying with the settings for fun could be so much fun