Well, I'm here because I went out searching for "wood furnace" "control" OR "controller" and was disillusioned.
When I found this thread, I had to sign up, log in, and say, "Go, Dan, go!"
We just bought a house west of Madison, WI. It has an owner-built wood furnace as a secondary heat source in parallel with an LP.
It's an odd duck. There is, what I've come to understand, a line-voltage thermostat in the first-floor hall which powers a rotisserie motor rigged to lift the air draft to full-open when heat is demanded. The lever arm on the motor shaft which lifts the draft gate also serves to stall the motor when it hits the "limit bolt."
A second plenum-mounted thermostat actuates the blower when plenum temperature hits the setpoint. Meanwhile, the rotisserie motor stays in stall mode until the hallway thermostat hits its setpoint and drops power.
Immediately, I wondered why-in-the-world there wasn't a controller to read all the inputs and control the draft-door position in a closed loop with the flue (and perhaps, I thought, the plenum) temperature. Immediately after, I started dreaming about a design.
I appreciate the wisdom of you wood-stove-loving aficionados who have distilled that wisdom from years of observation and experience. You need to tell me how to run a furnace because I am an idiot (and have the PhD to prove it), but my point is that--more and more of us are going to have to try wood to cut our energy costs--and the normal distribution being what it is, the preponderance of us are not going to love it.
So, we're going to burn green wood and run our stoves way too hot and just generally be a danger to ourselves and our neighbors.
An acquaintance has regaled me with the wonders of his pellet stove ("No ash! Think of it! 100% burn!") and while looking for that elusive after-market controller, I heard of Greenfire (
http://www.greenfirefurnaces.com/products.html) which I took to mean wood-log combustion can be very efficient too.
That's what brought me to thinking about and looking for a controller to optimize the process, and now I'm fairly convinced from earlier posts that, having set a match to the wood, I mostly want to make sure the fuel burns most completely. It will be nice if it can be damped down to reserve some of the fuel for later if it's not needed immed., but I'd rather it be burned up for the sake of clean air than left half-unburned going up the chimney.
Echoing what was desired earlier re: retrofit kits, I'm reminded of my first computer (a Zenith Z-100 from "Zenith [TV] Data Systems"). ZDS published a magazine for their customers that had articles on "things to do" with, and to, your Z-100. It came with as I recall 192K (that's 'kay') of RAM, but one of their engineers explained how he'd managed to use 256K chips to expand the memory to 768K. (I'll tell you we wet our pants at the prospect!)
But here's the kicker: at the end of three issues, I had the complete set of instructions, with photos, of the modifications, and one weekend I proceeded to take out the "motherboard" (new term for me) and CUT traces hither and yon with an Xacto knife while BENDING OUT PINS from specified ICs and soldering jumpers all over the place. I put it back together without a second thought and powered it up and began using my new gofast machine. It was only years later (I had been in my 20s at the time) that I realized what a delicate instrument I'd been fiddling with.
But, being the idiot that I am, I desperately want to drill holes in my furnace, bolt things on the side and top of it, wire in jumpers and have something that behaves like a decent human being for once.
As far as cost goes, you can sell me ANYTHING at ANY PRICE,
after you
prove to me that it's actually SAVING me money over N years. The pellet-stove guys have my attention that way.
Thanks for all the great comments in here.
Go, Dan, go! (One way to save costs: move from MA to IA...) :^)
