Computer Controlled VC Encore

[OK_Bill]

While gazing into the innards of my VC Encore 2n1 stove, I saw an opportunity to apply a little high-tech in order to better control air feed within the stove: take direct control of both primary and secondary air feeds by using a microcontroller with servo actuators on the air doors and thermocouples for temperature feedback. Game changer!

The primary goal here would be to have the ability to control both the stove body temp as well as the CAT combustion temp. The dc-servo actuators on the air doors would be able to positively regulate airflow through each air plenum - MUCH better than the existing thermo-spring in the VC stove. They could even totally shut down the stove if wanted. Burn performance data could be written to and SD card for post analysis. I will employ a 4x20 LCD display for user interface with button access to operational modes, user settings, etc.

Should be a fun project.... I have most of the parts to get started here in the shop now. I'm just getting the programming menus and LCD layout set up... more to follow...

 

[OK_Bill]

OK - so far here's what I have:

Operating Modes: "Auto-CAT" "Auto-STV" and "Manual"

In the Auto-CAT mode, the CAT target temp is specified and the system will throttle air to keep the CAT at target.
In the Auto-STV mode, the Stove (body) target temp is specified and the system will throttle air to keep stove body at target temp.
The programming logic for these modes hasn't been designed yet - I'm still just theorizing about how the system might work....
Manual Mode - user has direct control of air door positions.
There will also be a couple setup pages for user input. PID logic on control doors... probably...

I plan on using a 4x20LCD display with back light for the day-to-day user interface. The microcontroller will also interface with a PC or Mac via USB.

Thermocouples: There will be 4. One for the CAT; two for the stove body - these will be mounted high on the back of the stove L+R just behind the heat shield. Their input will be averaged for use as a "stove body" temp. And the 4th probe will be in the flue, just so we know what the flue temps are when the Encore is burning with the damper open. Also knowing how much heat is getting pushed out the stack, I can tweak for better efficiency.

Finally, I want to include a standard AC power supply with battery backup just in case power fails we still have control of the stove. And maybe a couple LED's: a green one that turns on when the CAT's in the operating zone and a Red one to indicate faults / overtemps. Of course, the LCD will also have messaging capability so it will read out a message of any kind.

Still working ...

 

[matt1@]

Sounds good to me

 

[Toploader]

Sounds like Greek to me but I'll be curious to hear about the end result.

 

[DougA]

Why not just have Siri run the stove.

 

[turbojoe]

OK - so far here's what I have:

Operating Modes: "Auto-CAT" "Auto-STV" and "Manual"

In the Auto-CAT mode, the CAT target temp is specified and the system will throttle air to keep the CAT at target.
In the Auto-STV mode, the Stove (body) target temp is specified and the system will throttle air to keep stove body at target temp.
The programming logic for these modes hasn't been designed yet - I'm still just theorizing about how the system might work....
Manual Mode - user has direct control of air door positions.
There will also be a couple setup pages for user input. PID logic on control doors... probably...

I plan on using a 4x20LCD display with back light for the day-to-day user interface. The microcontroller will also interface with a PC or Mac via USB.

Thermocouples: There will be 4. One for the CAT; two for the stove body: these will be mounted high on the back of the stove L+R just behind the heat shield. Their input will be averaged for use as a "stove body" temp. And the 4th probe will be in the flue, just so we know what the flue temps are when the Encore is burning with the damper open.

Finally, I want to include a standard AC power supply with battery backup just in case power fails we still have control of the stove. And maybe a couple LED's: a green one that turns on when the CAT's in the operating zone and a Red one to indicate faults / overtemps. Of course, the LCD will also have messaging capability so it will read out a message of any kind.

Still working ...

Someone that thinks like me...lol, keep us updated on your progress !!

I have 30 years automotive testing, last 15 years doing durability testing for a Catalyst Co. :O We have been kicking around doing something like this and monitoring Lambda. Wonder what Air/Fuel a stove runs ??
Would be to cool to use some new diesel technology with a re gen cycle...lol.. DFE injection...lol

 

[xman23]

It has been done. Of course I can't recall the follows name. He was at the Washington DC wood stove contest a few years ago.

Anyone recall the details?

 

[BrotherBart]

His name is Dan. Here is his website.

http://inveninc.com/

 

[OK_Bill]

His name is Dan. Here is his website.

http://inveninc.com/

Wow. Dan and I sure think alike. Looks like we're on the same page for sure!

I'm not planning on incorporating a fan though.. but very similar ideas.

 

[begreen]

Sounds like a good networking opportunity. Dan is good people.

 

[OK_Bill]

Turbo - I have no idea where air/fuel would be for a wood stove.

But imagine how long a VC Encore might burn if I could keep the CAT controlled where I want it? I'm going to separate & disassociate the primary and secondary air feeds so they'll be able to control independently. That will make it possible to run different air/fuel ratios for primary and secondary burns. It'll get "mixed" in the software.

One thing is for sure - it'll be interesting!

 

[DougA]

Hmmm. Great idea but as soon as you have injectors, 16 valves, electronic carb, turbo charged and the computer controls everything, I'm gonna be happy with my stove that has a little stick that gets hotter when you turn it right and cooler when you turn it left.

I like the basic model that you toss wood in when you're cold and it makes you all warm inside. Hey, if it weren't for guys like you, we'd all be typing on our laptops by candlelight. Good luck, it sounds like a great project.

 

[BrotherBart]

Dan spent a ton of money and time on Smartstove. Not as an add on but for manufacturers to incorporate in their stoves. It has been a while since we communicated but it seems he was greeted with no interest from them.

 

[turbojoe]

Turbo - I have no idea where air/fuel would be for a wood stove.

But imagine how long a VC Encore might burn if I could keep the CAT controlled where I want it? I'm going to separate & disassociate the primary and secondary air feeds so they'll be able to control independently. That will make it possible to run different air/fuel ratios for primary and secondary burns. It'll get "mixed" in the software.

One thing is for sure - it'll be interesting!

Would love to try a few different Catalyst Technologies but am still gathering info. It would be great to see an Air/Fuel and Temperature graph from a complete burn cycle.
Not sure BKVP would be cool with me welding in an Oxygen sensor boss on my new Blaze King... lol

 

[turbojoe]

Hmmm. Great idea but as soon as you have injectors, 16 valves, electronic carb, turbo charged and the computer controls everything, I'm gonna be happy with my stove that has a little stick that gets hotter when you turn it right and cooler when you turn it left.

I like the basic model that you toss wood in when you're cold and it makes you all warm inside. Hey, if it weren't for guys like you, we'd all be typing on our laptops by candlelight. Good luck, it sounds like a great project.

LOL, I agree.
Blaze King Princess Ultra Turbo Sounds cool anyway

 

[turbojoe]

His name is Dan. Here is his website.

http://inveninc.com/

Thanks for the link Bart, Talked to Dan today for at least an hour.Great guy ! Cool things planed for the BK

 

[OK_Bill]

For sake of clarity - let me emphasize the system I'm developing here isn't intended for any kind of commercial application. I just love to play around with all kinds of design projects. One of my first projects was to develop a software/hardware interface to simulate heat seeking missile tracking behavior - at NASA. I also worked on developing simulation software for General Dynamics and the USAF used to validate F16 flying qualities and performance. I wrote all the code myself. I've also worked extensively in aerospace doing aerodynamics, structural analysis and control system design. I'm currently working on a black project for helicopter rotor blades... and doing some outrageous things with microcontrollers

Designing a control system for a wood stove will be relatively easy. And low cost.

So, come play in my digital sandbox if you like. I hope readers of this thread will be entertained and there's a good chance we will learn a thing or two. I appreciate all the words of encouragement!

Turbo - this system will be fitted with an SD card interface for data logging. I'll log every parameter and use the results to refine the control feedback logic. Keep tuned!

 

[OK_Bill]

BOM:

Microcontroller: Arduino UNO R3 $25.00
Servos (2): Hobby grade dc PWM controlled $30.00
Omega Scientific Thermocouples (4): $112.00 lab grade units. 2 on stove body; 1 for CAT; 1 for flue
Thermocouple amplifiers (4): $60.00 these do all the cold junction & A/D corrections; serial comm with the Arduino
4 channel logic converter: $4.00
20x4 LCD w/backlight: $18.00
Data Logging unit: $20.00
Power Supply w/batt backup: $15.00
Misc items - enclosures / servo hardware / sec air throttle body: $40.00 (est)

Total damage: $324.00

plus lots of wood.

 

[turbojoe]

For sake of clarity - let me emphasize the system I'm developing here isn't intended for any kind of commercial application. I just love to play around with all kinds of design projects. One of my first projects was to develop a software/hardware interface to simulate heat seeking missile tracking behavior - at NASA. I also worked on developing simulation software for General Dynamics and the USAF used to validate F16 flying qualities and performance. I wrote all the code myself. I've also worked extensively in aerospace doing aerodynamics, structural analysis and control system design. I'm currently working on a black project for helicopter rotor blades... and doing some outrageous things with microcontrollers

Designing a control system for a wood stove will be relatively easy. And low cost.

So, come play in my digital sandbox if you like. I hope readers of this thread will be entertained and there's a good chance we will learn a thing or two. I appreciate all the words of encouragement!
Turbo - this system will be fitted with an SD card interface for data logging. I'll log every parameter and use the feedback to refine the control feedback logic. Keep tuned!

Nice background this should be a piece of cake and fun at the same time for you.
I spoke with Dan from Smart Stove today, I seek better control of the intake air system to better utilize the Catalyst and different Catalyst technology.
Thanks for sharing your project
I too am just doing this for my own challenge/Fun

 

[OK_Bill]

Are you building a system of your own, or using Dan's controller?

 

[mellow]

I had looked at building an arduino controller when I had my tube stove, for a cat stove it starts making less sense since they already cruise for long periods of time already, especially with models that have the bimetallic coil.

Dan is a good guy, I have been following his project for a long time, it was great to meet him at the DC event and see his setup in person.

1 thing I will add is always set it to close the damper and primary air on error or power loss.

 

[OK_Bill]

It would be great to meet Dan. I reviewed his website last night - he's certainly put tons of effort into his product.

I want to be careful here to not digress into any kind of comparison between what I'm doing and what Dan has already done. I have great respect for anybody who takes the initiative, the risk and the time to put a product in play on the market. Its too bad the stove mfgr's don't wake up and smell the coffee - Dan's work makes it clear there's much much more to be gained in performance with active control. So KUDOS to Dan!!

As for the VC stove I have, yes its a CAT stove. I instrumented the CAT a couple weeks ago and noted on a typical burn with the VC thermostat working, the CAT temps are all over the place. It would light off around 500F and then get up to 1400 or more, then slowly burn back down with lots of staggering in the temp profile as the wood pile shifted, and the draft changed during the burn. I could do better at controlling the burn with manual manipulation of the Pri air control. Not great.

The stove will put out tons of heat, but when its running hard like 1000+ CAT and stove body temps 600+ its too hot for my little house. I want a longer, lower cruise and that's why I want more control over the air. The metal coil thermostat on my VC Encore just doesn't have enough throw and the primary/secondary air systems are tied together (read: EPA) so the whole thing just doesn't throttle well from what I can see. This is VC's implementation of the thermo spring, and their air system. I'm gonna change ALL that

edit: UPS truck arriving today with thermocouple amps and logic shifter. More on the way from Omega soon...

 

[turbojoe]

Are you building a system of your own, or using Dan's controller?

Going to work with Dan and see how we can do on a Cat stove. I think Cat bed temperature should be considered as part of the control strategy but not sure 100%, not sure how hard the programing would be with two inputs determine air position. I understand the Fabrication/Catalyst end of doing this, not a programmer

 

[mellow]

Will be following this, the way this Appalachian is laid out with air controls on the door it would be a PIA to hook up servo's to it so I haven't bothered.

Now that I have put a thermocouple on the exhaust I am seeing higher temps than I thought I would with the cat active, looks to be sending a lot of heat up the stack. I see 400-450 at the exhaust with the cat running at 1500. Are you seeing the same on your VC?

 

[OK_Bill]

Turbo - great. Maybe you can chime in here and let us know how it works out.

The system I'm developing is a 2 servo system. I think the VC Encore is a great candidate for such a system because its easy to physically separate the primary and secondary air feeds so they can be 100% independently controlled. Although it would be unrealistic to think I can operate one side of the burn without affecting the other side (pri / sec and vice-versa) I do think they can be controlled with some degree of autonomy. We shall see!!

I do hope to RADICALLY increase burn time. I will write code that can control the stove in 2 automatic modes: Auto-CAT or Auto-STV. And of course there will be a manual mode too.

In the Auto modes of operation, I will be able to set a "target" temp for either the CAT or the Stove Body (STV) and the system will throttle air to hit those targets. Some air mixing will probably be necessary, and so there will be some mixing logic that I will have to get a feel for. That's basically how my system will work.

Here's an initial look at the 4x20 LCD layout I've come up with:

STV CAT FLU PRI SEC
560 1267 397 15 100 ← Real-time temps; servo position
--- 1200 BURN 05:37 ← TGT temps; timer
640 1284 AUTO-CAT ← Max temps; message line

The above display is in Auto-CAT mode, hence you see the target CAT temp (1200) and the STV target temp is blanked out.
"STV" refers to the Stove Body temp - its actually going to be an averaged value of 2 thermocouples bolted high on the back side of the stove.