Ahh, sweet scope creep! Usually it’s the death of a nice, simple little hack. But once in a hundred times, a small hack doesn’t get buried under the extra features, but instead absorbs them in stride and blossoms into a beautiful system. [rockfishon]’s Arduino-powered wood stove controller is one of these beautiful exceptions. (OK, we’d admit that it could use a fancier faceplate.)
He started off simply enough, wanting to connect a thermocouple to an Arduino, read out the value, and issue an alarm when the temperature got too high. But who could stop there? Just one air-baffle servo away from a closed-loop heating control system? So [rockfishon] added a display and a few more buttons and has a system that will keep his wood-burning stove running at exactly the right temperature, even overnight when nobody’s around to tend it. As a bonus, everything is logged for later analysis.
The code is relatively straightforward, and can be found in this Gist. If you’d like to build your own, you’ll need an Arduino Mega and can then get the control board made for you at OSHPark. Judging from the comments on the Hackaday.io project page, a couple people have already tried this out. We’ve seen other wood-stove monitoring hacks before, but this is the first we’ve seen that closes the control loop. Very cool.
A thermocouple does not make a thermopile that could actually power the ‘duino. Mains power runs it, right? Doing both, now that hacking.
What? If you want to do that start a project on Hackaday.io
You appear to have been drinking sir. Sober up and try to comment again.
Indeed there are such things that can run control circuits for gas-fired central heating.
And on water heaters too. But they only supply enough current to hold open a solenoid valve, not enough to actuate the valve (you need to do that by hand).
Thermoelectrics (a thermopile) could be used as a power source though. Linear technology has an IC specifically for that-
http://cds.linear.com/docs/en/datasheet/3108fc.pdf
Many new gas water heaters are in fact using self powered digital controls. My best guess as to how they work is that they charge up a supercap in order to get enough power to operate a stepper motor.
Good job! I have a similar system running for my parents’ wood boiler, it has 3 relays controlling the damper motor, boiler to tank pump and tank to house pump (the wood boiler is in a separate building).
OK cool project and I’ve been watching it, however i’m confused about something, in the components he nowhere mentions the oshpark but he then mentions that you need one, what am i missing here?
@Gambler, OSHPark.com makes circuit boards. You would need the board that OSHPark makes to hold all of the listed components. That or make the circuit board yourself, but that can be a daunting task for some.
I did not use a circuit board. The project can be constructed without one.
“…but this is the first we’ve seen that closes the control loop. Very cool.”
You mean very hot, no? It is a stove after all. (c:
Just kidding.
So, how many truck loads of Arduinos do you have to burn in a typical winter?
Yay, Arduino-burning stove warms your bones AND your heart.
Pee-Ewe that would stink up the whole valley!
If your considering doing this on a wood burner with a water tank incorporated, take special care you don’t accidentally make a bomb. Theres a massive amount of energy in a wood furnace and its difficult to put one out if it gets out of control.
I have had my wood furnace monitored for a couple of years now with one of the daenet ethernet relay+ sensor boards, and I have the board switching a relay on to turn on the circulation pumps for the heating, overheat alarm generates a trap via snmp etc.
However, the flap is done by the original mechanical flap valve which is the original supplied with the system. Its literally a wax capsule touching the water jacket and expanding which moves an arm on it that connects with a chain to the flap and its deliberate that I’ve left it that way.
The reason I have avoided automating this, is that the furnace can run away if the power goes out if it was done by a servo or electronic system unless it fails closed every time. And that means boiling the water inside, and blowing out steam out the pressure release valves, which melt the insides of the valves if the boil event happens for too long. Yes the mechanical valve can stick too but the heating load can cope with taking that away and you soon notice because it stops moving in use.
But keeping the flap controlled by the mechanical water valve keeps it as a second independant redundant safety system.
Speaking as someone who has experimented, and also who’s had to change the blow off valves on similar systems when power has gone out for extended periods…