A Wireless Wood Stove Monitor

[Michel] has a wood stove in his basement for extra heat in the winter. While this is a nice secondary heat source, he has creosote buildup in the chimney to worry about. [Michel] knows that by carefully monitoring the temperature of the gases in the chimney, he can hit the sweet spot where his fire burns hot enough to keep the creosote under control and cool enough that it doesn’t burn down the house. To that end, he built a wireless wood stove monitor.

The first version he built involved an annoying 20 foot run between the basement and living room. Also, the thermocouple was mounted on the surface and made poor contact with the chimney. Wood Stove Monitor 2.0 uses a probe thermometer on an Exhaust Gas Temperature (EGT) thermocouple to measure the temperatures. The intel is fed to a thermocouple amplifier to provide a cold-compensation reference. This is shielded so that radiant heat from the stove doesn’t compromise the readings. An nRF24L01+ in the basement monitoring station communicates with another module sitting in the living room display so [Michel] can easily find out what’s going on downstairs. When it’s all said and done, this monitor will be part of a bigger project to monitor power all over the house.

Interested in using a wood stove to help heat your house? Why not build your own?

25 thoughts on “A Wireless Wood Stove Monitor

      1. Canada, actually but there is a growing trend against this in many countries due to concerns with air quality more than anything else. The rules here are becoming so tight that wood-fired pizza and bagel ovens, once fairly common, are disappearing due to stricter bylaws, a huge loss in the eyes of some (like me.)

    1. Cite a source of fuel wood getting hammered by restrictions? I’m interested in knowing, because I live in the US and my *primary* heat source is wood. Burning wood is actually carbon neutral as it originates from atmospheric carbon rather than underground (i.e. petroleum) sources. Air quality is sorta moot, as the EPA cracked down on stoves a few decades ago so they burn nearly smokeless these days.

      My advice about creosote is that you should not oversize your stove, because it will never run at its cleanest except in the coldest conditions. Go a bit on the small size, and you won’t have any creosote. I clean my chimney once a year and all I get is a light brown powdery ash. Zero creosote. A better strategy is to get two stoves and put in two chimneys and run only one when it’s mild, and fire up the second one when needed for the bitter cold days.

      1. The city of Montreal has a bylaw that will prohibit the use of open fireplaces as of Oct. 1, 2018 and effect a complete ban on fireplaces and stoves as of 2020. Similar bylaws are going in in other cities like Puget Sound, Washington. In the States, as I understand it, the EPA has made some very stringent regulations that will apply nationally in the US which apparently cannot be met by some 80% of wood burning appliances currently in use.

        1. Makes sense in the city of course. I’m quite surprised that cities of that size haven’t banned wood heat long ago. My town is nowhere near the size of Montreal and I think wood heat is long ago banned within the town limits. I could be wrong but pretty sure new constructon is barred from wood heat in town, there may be grandfathered clauses.

      2. I understand your point about carbon neutral but I dont agree. Also petroleum comes from Carbon that once was in the air. Not burning the wood, but leaving it to go into petroleum is just a way to keep it out of the atmosphere longer.
        Actually, not chopping a tree for burning, and use gas or petroleum is better because the tree can still go on taking Carbon out of the atmosphere.
        Having said that, i have no problems burning a woodfire, as long as we keep our forestssize intact and preferably enlarge it

  1. First of all, that “black on blue” is a crime against humanity (on the display) and should be fixed ASAP.

    Besides that, I live in Sweden where wood fired furnaces are quite common, not just for “extra heat” but rather “all heat”. And it is quite common to measure the temperature of the exhaust gases like this. But not because of the sot issue (we have chimney sweepers for that), but rather for efficiency reasons it is important to not loose to much of the energy into the chimney. Also a common setup is to have ackumulator tanks where the heated water from the boiler is stored.

    In my furnace setup when the exhaust gas starts to get warm, it will turn on a pump that circulates the water from the bottom of the furnace to the top. Only when all the water in the furnace is at a higher temperature, cold water will be brought in from the ackumulator tanks, and is then mixed with already pre-heated water, all this for a more efficient heat transfer, so that you don’t keep bringing in cold water at the start which would cool down the fire. A video of how this works https://youtu.be/4FhcehmtEVo

    I also have a 1-wire network setup so that I can monitor the exhaust gas temperature to see if it gets too hot. So I have built something that looks similar to the thing in this article, but also measure the different water temperatures (of course in a setup like this the radiators in the house are heated by water).

  2. One reason wood stoves might get a bad rap is the fact that “you can’t outlaw stupidity.” For example, people don’t prepare correctly for heating season by gathering wood in time for the moisture content to be low enough, then their chimneys smoke blue from them trying to burn green wood. Or, the stove is not operated correctly or is not sized correctly, allowed to smolder, and make great clouds of smoke. Since it is difficult or impossible to regulate these behaviors, the government needs to make laws against burning wood period. Stuff like this irritates me to no end.

    1. Yes there are idiots, however in many cases it’s just plain ignorance and being ripped off by unethical suppliers. I have nothing against wood fueled heating. Up until a few years ago we had our own woodlot that had been in the family for several generations, and we knew what we were doing. We have since sold it as did the other owners in the area, to be part of a wildlife sanctuary, and I stopped heating with wood shortly after because of the trouble I had finding good fuel.

  3. We (living in Belgium, Europe) are using a high-efficiency soapstone fireplace using only clean and dry willow wood from our own garden. Due to the very high heat in the fireplace the soot buildup in the chimney is next to zero. I know what i’m talking about because when we invited a chimney sweeper after five winters he was surprised to admit the chimney was spotless.
    Most importantly, i’m pretty sure that this setup with this kind of fuel source beats anything in efficiency and environmental concerns except for sitting in the cold during winter time.

  4. I have a inverted flame wood furnace made by HS Tarm but I live out in a very rural part of France, and lots of houses locally use wood as their primary heat source also. Its very efficient in itself, and the chimney is connected at the bottom of the firebox so methanol and smoke released from the upper logs while the fire is burning has to pass the flame front to exit both cleaning up its output and recovering the energy that would normally go up the chimney from the methanol release. I can run it on oil via another input which is the other main fuel choice in the locality, but wood is cleaner, better for the environment and it grows in the woods nearby.
    On my furnace I have some ds1820’s monitoring the temperature of the water jacket surrounding the furnace, and when that rises above 77C, it switches on circulation pumps which drive the underfloor heating + radiators in the house, thus storing that heat into the slab of the house without chilling the jacket back into the zone where creaosoting happens.
    I used a denkovi daenet2 ip connected board because wireless works really badly in old stone properties (like this one) and I trust copper to maintain a signal. We alter the floor temperatures via its web interface or via snmp also for some HA hookin. Its nice to get a quick view of how warm the furnace is and get an alert from another system when the temperature starts to drop below a certain threashold (indicating its time to go push some more logs into it, every few hours when ran hard)
    Not as diy, but works and I have two of the denkovi boards, one ready to swap in should the other go bad mid winter when its important to get the heating back on quick. That was my main driver behind not rolling my own, anyone can screw the replacement board in if I’m working away and its ready to go. My previous house was completely home rolled and in reality the only person who could fix/diagnose it was me, which is great until you come to sell the house.
    Having read this I will probably look into adding a thermocouple for chimney gas heat just as a extra input to see if it adds any finer grained logging so we can tweak burning temperatures maybe.

  5. If you want real efficiency, you are talking rocket stove mass heater. I’ve watched interviews where it is 20 below outside, toasty inside at 2 in the afternoon, and the last time that the stove was fired up was 7 the night before! (The person being interviewed went from 4 cords of wood per winter with a regular wood stove to half a cord with the RSMH.) I’ve also watched a teardown of a RS water heater box that had less than an inch of soot after two years of operation. There was a HaD entry about a guy who built one in his living room, and the exhaust vent was a piece of flexible dryer duct inserted into a hole in a piece of cardboard covering his fireplace cavity! (FWIW, they are also known for their air quality safety; even a three-gallon bucket-sized charcoal burner can have CO levels drop to below ten parts per million once it gets up to temperature in 6-8 minutes.)

  6. Only who has a wood stove, will understand the problem with wood stove. If you use wireless wood stove monitor, your work will be very easy. Many people nowadays do not like wood stove because of wood feeding but its fuel is cheap. It has pros as well as cons. So decide before you buy it.

  7. Fortunately I live in rural Vermont USA where almost the only rule in this town is “Don’t Be Stupid”. I can build a barn or carry my handgun into the bank with no permits. And I cut my own firewood and manage my own woodstove for last 30 years. Updating the controls with Arduino so I don’t forget to stoke wood or turn the damper down.

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