My adventures in Woodstove Monitoring

[neil_s]

Hi all, longtime lurker, first real post.

I’ve been hanging around here for a while reading threads about draft issues, dampers, flue temps, creosote, all of it. This forum has probably saved me from doing a few dumb things already, so thanks for that.

I wanted to share a project I’ve been working on and get some honest feedback. I’m not trying to sell anything here, genuinely curious if this solves a real problem for anyone besides me.

A little background

I didn’t grow up with wood heat.
Long Island kid. Then NYC (radiators clanking all night), then SF (basically no heat), then back to NYC again.

A few years ago my wife convinced me we should move to Vermont. We bought a house that came with two woodstoves.

I was not confident.

My wife grew up here, but her dad always ran the stove, so neither of us actually knew what we were doing. She was pregnant, winter was coming, and suddenly I was responsible for keeping the house warm without burning it down.

I didn’t really understand draft, negative pressure, flue temps, or why sometimes I’d burn through a ton of wood and still end up cold.

The actual problem

I work from home, usually on the other side of the house. I’d load the stove, get sucked into work, and forget about it for hours. By the time I came back, the fire was dead and the house was cold.

I tried a magnetic thermometer. It helped, but only if I was standing right there looking at it.

What I wanted was something that would quietly let me know what the stove was doing without me babysitting it. Something that could nudge me before the fire died, or warn me if I screwed up and left the air open too long.

The build

I’m a hardware / software guy by trade, and I’ve gotten into woodworking since moving up here (clearing land, chainsaws, the usual Vermont stuff.)

We had to take down a big old black walnut tree on our property. A neighbor helped me mill it, and I decided to combine the two hobbies.

I built a wireless stove monitor I call Oru.

How it works (quickly, without going full engineer)
• There’s a K-type thermocouple magnetically attached to the flue.
• I didn’t want electronics near the heat, so I built a separate “sidecar” module that sits about 3-6 feet away.
• The braided probe wire helps shed heat before it ever reaches the electronics.
• Inside is an MCP9600 amp and an ESP32 sending data wirelessly.

The part I’m most happy with is the display.

Instead of numbers, there’s a small walnut box that sits on my desk or in the kitchen. It just glows:

• Blue/gray: stone cold
• Pale yellow: too cool / creosote territory
• Amber: cruising along, good burn
• Red: hotter than I want
• Pulsing red: fast spike — pay attention now

You don’t have to look at an app. You just glance across the room and know what’s going on.

What changed for us

My wife keeps the base in the kitchen now. She says the amber glow is reassuring without being distracting.

For me, the app alerts are huge. I have it ping me when the stove drops to a restartable coal bed, so I don’t waste kindling on cold starts. It also saved me once when I got distracted on a work call and the stove started climbing faster than expected, and the flue pipe was starting to glow.

I sleep better on overnight burns too, because it will notify me if something actually changes.

Why I’m posting

I’m getting ready to build a small batch of these using that same walnut tree, and I’m trying to figure out if this is something other stove owners would actually use, or if I’ve just built a fancy solution to my own anxiety.

A few questions for the group:
• Would something like this be useful in your setup?
• For overnight burners: what alerts would you actually want?
• Would you rather rely on light alone, or light + phone notification?
• What am I missing?

Happy to hear criticism — I know this crowd doesn’t sugarcoat things, and that’s exactly why I’m asking.

Thanks for reading!


The magnetic thermoprobe


The base on my office dresser


The Raw slabs

 

[NickW]

That's awesome! I love it! If I were going to use this without running a flue probe with an alarm, I would want an audio alarm at pulsing red in case I wasn't looking at it or was in another room...

 

[begreen]

It sure is good looking and nice for general guidance. What's missing is actual temperature. This is particularly important in the startup phase. Also, that looks like double-walled stove pipe. If so, a probe thermocouple will be much more responsive and accurate.

 

[neil_s]

It sure is good looking and nice for general guidance. What's missing is actual temperature. This is particularly important in the startup phase. Also, that looks like double-walled stove pipe. If so, a probe thermocouple will be much more responsive and accurate.

The actual temperature is in the app, which I haven't dropped an image of. I dropped on here below.

I am curious though, what does the temperature tell you that it's so important that you have it? Why isn't just "burning optimally" or "too low" good enough?

 

[neil_s]

That's awesome! I love it! If I were going to use this without running a flue probe with an alarm, I would want an audio alarm at pulsing red in case I wasn't looking at it or was in another room...

Great point. Would your phone be sufficient for this or would you want the device to make noise as well?

 

[begreen]

The actual temperature is in the app, which I haven't dropped an image of. I dropped on here below.

I am curious though, what does the temperature tell you that it's so important that you have it? Why isn't just "burning optimally" or "too low" good enough?

That's neat, very cool. Is there also an audio alarm tied in with the app?

Flue gas temp is fairly important on startup of a secondary burner woodstove. It's super helpful for knowing when to start closing down the air and how much. This thread illustrates the value of an accurate flue temp in starting the stove.

Thread 'Starting a fire and running an EPA stove'

Jan 17, 2020

Questions about starting a fire and avoiding a runaway stove come up so frequently I decided to document starting our stove. This is a Pacific Energy Alderlea T6 with about a 3 cu ft firebox. The stove is connected to a straight-up, 20' interior flue. The outside ambient temperature is 34ºF. The blower was off all the time for these shots. The firewood is douglas fir at about 17% moisture content. This is a N/S loading. An E/W loading start will follow.

NOTE: as testing will show, the older Condar flue thermometer is reading low. It needs recalibration.

There are 3 instruments shown.

1. ...

• begreen
• Replies: 89
• Forum: The Hearth Room - Wood Stoves and Fireplaces

• 

 

[NickW]

Great point. Would your phone be sufficient for this or would you want the device to make noise as well?

Personally I'd have the device. Potentially different people could be operators and rather than having everyone have an app or be connected...

 

[neil_s]

That's neat, very cool. Is there also an audio alarm tied in with the app?

Flue gas temp is fairly important on startup of a secondary burner woodstove. It's super helpful for knowing when to start closing down the air and how much. This thread illustrates the value of an accurate flue temp in starting the stove.

Thread 'Starting a fire and running an EPA stove'

Jan 17, 2020

Questions about starting a fire and avoiding a runaway stove come up so frequently I decided to document starting our stove. This is a Pacific Energy Alderlea T6 with about a 3 cu ft firebox. The stove is connected to a straight-up, 20' interior flue. The outside ambient temperature is 34ºF. The blower was off all the time for these shots. The firewood is douglas fir at about 17% moisture content. This is a N/S loading. An E/W loading start will follow.

NOTE: as testing will show, the older Condar flue thermometer is reading low. It needs recalibration.

There are 3 instruments shown.

1. ...

• begreen
• Replies: 89
• Forum: The Hearth Room - Wood Stoves and Fireplaces

• 

There is an audio alarm tied in with the app. It also uses apple's priority notification system if you use an Iphone, so it can bypass sleep settings (if you let it)

Thanks for the thread link. Really helpful. To be honest, the first few prototypes of this product were just a raw thermoprobe that I stuck into the flue. The thermoprobe was rated for 1000 deg fahrenheit, but I didn't like the idea of people having to do that, so I decided against that option. I wonder if it'd be useful to offer both a magnetic thermoprobe option as well as the raw thermoprobe option for the folks that want to measure the gas temperature.

 

[John Lehet]

I would mostly want the light to show that it's time to close the bypass, that it's hot enough for the cat to fire.

Dependency on an app with an extremely small company (just you), wouldn't be encouraging to me. iOS? Android? Both? Keeping an app updated as mobile operating systems change in the future is potentially hard. And they will change, every year.

I did just a bit of iOS development around the time of iOS7, and in the middle of my work the UI changed, several other expectations from Apple of what an app would do changed, and Swift was just introduced and obviously the coming thing. I suddenly saw how much work it would take to keep an app updated and moving into the future. And in recent years I've had many apps for iOS get abandoned instead of maintained.

But if it was just a hard connection to your beautiful box, that would be nice.

I'm trying to figure out how to get a cat probe on my Woodstock Progress. It's a bit vexing and without any info I can find anywhere. I'll persevere and get it eventually. With such a probe, it would also be nice for a box like yours to have a light -- "catalyst is active." But I guess that would be a stretch.

Oh, and welcome to Vermont. Hope it is suiting you well. I like it here.

 

[neil_s]

I would mostly want the light to show that it's time to close the bypass, that it's hot enough for the cat to fire.

Dependency on an app with an extremely small company (just you), wouldn't be encouraging to me. iOS? Android? Both? Keeping an app updated as mobile operating systems change in the future is potentially hard. And they will change, every year.

I did just a bit of iOS development around the time of iOS7, and in the middle of my work the UI changed, several other expectations from Apple of what an app would do changed, and Swift was just introduced and obviously the coming thing. I suddenly saw how much work it would take to keep an app updated and moving into the future. And in recent years I've had many apps for iOS get abandoned instead of maintained.

But if it was just a hard connection to your beautiful box, that would be nice.

I'm trying to figure out how to get a cat probe on my Woodstock Progress. It's a bit vexing and without any info I can find anywhere. I'll persevere and get it eventually. With such a probe, it would also be nice for a box like yours to have a light -- "catalyst is active." But I guess that would be a stretch.

Oh, and welcome to Vermont. Hope it is suiting you well. I like it here.

Hey!

Yeah I've been building apps for a long time, I have a couple in the app store right now that I maintain as well. I've generally built most of my apps now using React Native, which makes life a bit easier if building for both iOS and Android. My iOS apps still have native swift code for bridging into things like LiveViews, but my UI's are all built with React to keep UX similar across devices. React Native has gotten really good over the last 4 - 5 years.

When you say "just a hard connection" do you mean like offering a data port like USB C or a webserver that published stats directly from the box? That could be possible given the chipset I'm using and would be fun to play around with.

I like the idea of that with the cat probe. A few friends and I have talked about the idea that we need multiple probes on the sidecar that are measuring different inputs i.e. (1. for flue temp, 2. box temp, 3 cat temp) and have those translate to specific insights that the box could then communicate. Definitely something I'm open to playing around with!

Thanks for the welcome We've been here for a while and love it so far. Our little one is definitely a born and bred Vermonter.

 

[John Lehet]

When you say "just a hard connection" do you mean like offering a data port like USB C or a webserver that published stats directly from the box?

I was thinking not that hard a connection, probably "hard" was the wrong word -- was thinking maybe more like bluetooth or a way to bypass the app.

But now that you mention it, robust data logging of a few parameters would be cool. And that would of course be best through an app.

There's a guy on reddit who data-logs surface temp, cat temp, and exhaust gas. He can create graphs. With his Hearthstone Mansfield and thermal mass, those graphs are interesting, at least to me. He annotates the graphs with info the sensors don't know: pounds of wood, burn rate. I would definitely be interested in doing that if it didn't involve wires to an ugly box on the hearth. He also runs a wire to his chimney top, which is valuable information, but I don't think I want to run that wire -- not sure how that wouldn't be ugly. He still posts those graphs sometimes, but he hasn't posted details about his setup recently.

 

[neil_s]

I was thinking not that hard a connection, probably "hard" was the wrong word -- was thinking maybe more like bluetooth or a way to bypass the app.

But now that you mention it, robust data logging of a few parameters would be cool. And that would of course be best through an app.

There's a guy on reddit who data-logs surface temp, cat temp, and exhaust gas. He can create graphs. With his Hearthstone Mansfield and thermal mass, those graphs are interesting, at least to me. He annotates the graphs with info the sensors don't know: pounds of wood, burn rate. I would definitely be interested in doing that if it didn't involve wires to an ugly box on the hearth. He also runs a wire to his chimney top, which is valuable information, but I don't think I want to run that wire -- not sure how that wouldn't be ugly. He still posts those graphs sometimes, but he hasn't posted details about his setup recently.

If I were to open up an API to the data (it is your own data after all) would that be something that would provide a bit more of a sense of security? That way, you're not dependent on my app, you'd just be able to access the data directly and do whatever you want with it?

 

[Eman85]

I wouldn't be interested in the gadget but I'm sure many would. Seems people want to complicate something as basic as a fire in a box.

 

[bigealta]

I like the glow box. Sort of a modern lava lamp feel.
I can see this as a good Christmas present. For work at home people that work in rooms away from the woodstove or stoves this would be nice. It's so easy to get wrapped up in work and other distractions and space out on the woodstove.

And as a runaway stove alert with the flashing red lights, that could save your stove from cracking. That alone would be worth getting this.

 

[neil_s]

I wouldn't be interested in the gadget but I'm sure many would. Seems people want to complicate something as basic as a fire in a box.

I mostly built it for the new generation of burners (like my neighbors who just moved up here) who don't have that intuition yet and are terrified of burning the house down.

It’s basically 'digital training wheels' until they learn to read the fire like you do.

Appreciate the feedback, it definitely isn't for everyone!

 

[neil_s]

I like the glow box. Sort of a modern lava lamp feel.
I can see this as a good Christmas present. For work at home people that work in rooms away from the woodstove or stoves this would be nice. It's so easy to get wrapped up in work and other distractions and space out on the woodstove.

And as a runaway stove alert with the flashing red lights, that could save your stove from cracking. That alone would be worth getting this.

You nailed the use case perfectly. I work from home too, and I used to have two modes:

1. Paranoid (checking the stove every 20 minutes).
2. Distracted (forgetting it exists until the room is 90 degrees).

The 'Red Pulse' is basically insurance against that distraction. Like you said, it’s a lot cheaper to buy a blinky light than to replace a cracked cast iron stove.

Thanks for the kind words

 

[davargo]

I love the walnut display box!

I made a similar monitoring system using a Raspberry Pi, some thermocouples, and a Node Red application. My wife works from home periodically and wanted to know what the stove was doing from her computer and get notifications if it needed attention. We have a Vermont Castings Encore, notoriously difficult to operate. I have an old Surface tablet set up in the living room with the UI pulled up all the time. There are popup, visual (color), and audible alerts when the stove needs to be reloaded or is getting too hot. I have the actual temperatures displayed on the screen, along with a time history of the temps. We find that we use the temp trends more than the actual value, this has allowed us to prevent scary runaway situations at least twice before temps actually got out of control. Maybe the rate of blinking combined with the color can show you the temp trend over the last XX minutes?

 

[EbS-P]

I run Auber AT200s on both stoves. Downstairs is WiFi.

Thoughts. Flue gas temps just respond so much faster than pipe temps. You can stop chasing your own tail. Adjust and in 20s you see a temp change. It’s easier to run on realtime data than to self calibrate a stove input to an experienced response.

Features.
1st overfire alarm
Second. Current temp. Could be numerical could just be a color but I need that info in minimum 50 degree increments. Or numerical.
Third past temps. Is the temp going up or down a how fast.

I like my ecobee app and my Tesla app and my MEATER app. If I had a wood stove app that would be great. But I don’t want it to be totally app based.

Each install is going to run at a different temp. So there need to be some calibration process/procedure. My insert runs at 800 degrees flue gas temps alarm is at 1050.
My stove I’m measuring liner temp. It runs at 450. Alarm at 575.

 

[begreen]

I wonder if it'd be useful to offer both a magnetic thermoprobe option as well as the raw thermoprobe option for the folks that want to measure the gas temperature.

Definitely. Some folks have single-walled stove pipe and some have double-walled.

mostly built it for the new generation of burners (like my neighbors who just moved up here) who don't have that intuition yet and are terrified of burning the house down.

It’s basically 'digital training wheels' until they learn to read the fire like you do.

I use the flue temp to guide me with almost every startup fire in the stove and that's after a half century of stove operation. The digital temperature readout on our Auber has been one of the most instructive and helpful pieces of hardware I have used. It's even more of an asset to my wife when she runs the stove.