Automating wood stove with Pi

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Woodlover

New Member
Feb 17, 2022
5
Eastern NC.
Good info. You must burn some pretty large splits if 3-4 fill the firebox. Takes 8-9 for me.

Depending on the weather Ive been doing 8 or 12 hr reloading schedules with my F45 with stove temps maxing out around 550-600 and slowly dropping to 150-200 by reloading time. Stack temps usually cruise 400-550 for first couple hours before falling off.
Hope I'm not out of bounds here. I'm a retired electrician. When I started out high tech was a 120 v relay with a light across the contacts. I've worked with programable logic controllers. I can see monitoring flue temp for safety. I know the dangers of a run away stove, been there, done that. One of the biggest scares of my life. Fell asleep and woke up I was hit with reality 10' from my silent flame wood heater made in Tarboro NC. Still using it 30 years now. My question is why go so high tech. Many years ago a friend wanted a way to control his air flow to maintain temp. My simple solution was to mount a solenoid actuator to the damper breaking it through a 120 volt thermostat. Temp dropped solenoid energized opening damper. Temp reached and solenoid closed. Very simple design worked great. This is not meant to insult just curious why so high tech.
 

stoveliker

Minister of Fire
Nov 17, 2019
6,216
Long Island NY
Even better for when the power is out: a (calibrated) bimetal coil to operate a valve .
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,312
South Puget Sound, WA
Temp dropped solenoid energized opening damper. Temp reached and solenoid closed. Very simple design worked great. This is not meant to insult just curious why so high tech.
On/off air supply would not work well with most modern stoves. There often is a need to close the air incrementally and the variables thrown at the fire by draft strength, wood species and loading, wood dryness, etc. sometimes require an in-between air control setting.
 

Woodlover

New Member
Feb 17, 2022
5
Eastern NC.
On/off air supply would not work well with most modern stoves. There often is a need to close the air incrementally and the variables thrown at the fire by draft strength, wood species and loading, wood dryness, etc. sometimes require an in-between air control setting.
Thanks for your reply. I love my wood stove and so true about the variables. I don't even fire up my stove unless temps drop to low 40's because it's really to big for 1500 sq' home. I separate all my wood so with mild temperatures I burn poplar and when it gets cold I use the oak.
 

snobuilder

Feeling the Heat
Dec 16, 2021
432
WI
Even better for when the power is out: a (calibrated) bimetal coil to operate a valve .
The OP is on one end of wood heat technology with the good old fashioned bimetal coil on the other. I fall in the low tech group having great results with my DAKA wood furnace low tech bimetal air control.
I'm finding it works along with my added secondary burn array as well .
 

TabeaK

New Member
Jan 15, 2022
9
NJ
Love this post: question on the surface temperature probe: the Amazon link says it is only rated to 350F - so how does that work? I am looking for a surface probe to use that will work within the temp ranges of an old fashioned magnetic thermometer and can actually be stuck to the top of my wood stove.
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,312
South Puget Sound, WA
Love this post: question on the surface temperature probe: the Amazon link says it is only rated to 350F - so how does that work? I am looking for a surface probe to use that will work within the temp ranges of an old fashioned magnetic thermometer and can actually be stuck to the top of my wood stove.
 

GrumpyDad

Minister of Fire
Feb 23, 2022
553
Champion, PA
AH I just saw this project. Super cool. I thought about doing something like this as I have experience with coding/hacking things together (scripts etc), but am opting for an indoor ring camera that I can quickly view my glass and temps once I put in a digital temperature system (if I really care to). This way I can see what is going on statistically and visually through the glass (somewhat, my stove is a soot monster ..had I known...). And it's super easy/cheap to do. I like that I can turn the sound on as well and 'hear' whats going on too.
 

jotulf45v2

Member
Sep 22, 2021
60
CT Shoreline
Love this post: question on the surface temperature probe: the Amazon link says it is only rated to 350F - so how does that work? I am looking for a surface probe to use that will work within the temp ranges of an old fashioned magnetic thermometer and can actually be stuck to the top of my wood stove.
The type K thermocouple I'm using is rated up to 2300F. The STT is just two bare wires under a magnetic thermometer and the temp is within 50* so it's pretty accurate. I trust the thermocouple over the magnetic tstat but they each keep the other honest :)

Since the original post I added the 2nd pi board to listen to the temperature updates and display them using an LED screen. I'll post a pic of the setup including the node-red setup later.
 
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TabeaK

New Member
Jan 15, 2022
9
NJ
The type K thermocouple I'm using is rated up to 2300F. The STT is just two bare wires under a magnetic thermometer and the temp is within 50* so it's pretty accurate. I trust the thermocouple over the magnetic tstat but they each keep the other honest :)

Since the original post I added the 2nd pi board to listen to the temperature updates and display them using an LED screen. I'll post a pic of the setup including the node-red setup later.
Oh, so you literally stuck the sensor wires under the old fashioned stove to thermometer? I missed that, sorry! Do you have a product number/link if the probe you are using?

I did find a magnetic McMaster probe rated to 1000F, but the probe alone is $200, so looking for alternatives.
 

TabeaK

New Member
Jan 15, 2022
9
NJ
Installed with a #10 screw? Doesn’t that mean I have to get a hole into my stove top?
 

jotulf45v2

Member
Sep 22, 2021
60
CT Shoreline
Oh, so you literally stuck the sensor wires under the old fashioned stove to thermometer? I missed that, sorry! Do you have a product number/link if the probe you are using?

I did find a magnetic McMaster probe rated to 1000F, but the probe alone is $200, so looking for alternatives.
The probe I got was RuoFeng K Type and goes for ~$8. This goes in my double wall chimney pipe and is read by my Pi. The probe needs to be at least 12" above the stove but below 2ft. Mine is somewhere in between at like 22" I think. Your stove manufacturer should have it noted as what's recommended.

For the top of the stove, the type k wire I got was from pi's ecommerce site but you can find a similar one on amazon and it connects to the pi the same as the probe (via 2 wires).
 
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begreen

Mooderator
Staff member
Nov 18, 2005
96,312
South Puget Sound, WA
Installed with a #10 screw? Doesn’t that mean I have to get a hole into my stove top?
Yes, that is an option, or just place a steel, cast iron, or stone weight on it. If the stove has a convection lid it might be able to be wedged under it.
 

jotulf45v2

Member
Sep 22, 2021
60
CT Shoreline
As promised, here's a pic of my screen. This 2nd pi also uses node-red and uses MQTT to listen to temp updates and displays them on an LCD screen I bought off amazon. The connectors had to be soldered onto the board which was unfortunate but it works great.

As for the setup, node-red listens for an mqtt topic and there's a package I'm using to render the numbers onto the screen. Since I have two temps I want to see and not enough room on the screen to show it, I have a 2.5s delay to toggle the temp being shown. So every 5s I get a new temp from my sensors and I show each temp for 2.5s before the next update. P stands for probe which is my flue temp, S stands for stove top.

IMG_9559.PNG IMG_9558.jpg IMG_9557.jpg IMG_9560.PNG
 

Todd

Minister of Fire
Nov 19, 2005
9,791
NW Wisconsin
Pretty cool stuff, thanks for sharing. Have you done this with a full load and just let it go for 12 hours?
 

jotulf45v2

Member
Sep 22, 2021
60
CT Shoreline
Pretty cool stuff, thanks for sharing. Have you done this with a full load and just let it go for 12 hours?
Yup, last season it was 24/7 for months. It only keeps the last days worth of data so the graph is still readable.