Computer Controlled VC Encore

turbojoe · Dec 9, 2014

OK_Bill said:
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.
i
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...

I figured a bed temperature graph of a burn cycle would be all over the place.
It's hard to hold a cat at a steady temp while in Exotherm. This is the state i want to hold mine at as long as possible.
A cat can be active and not lit off, it's still converting some CO but there is not the benefit of a 1200/1500 F Cat heating the stove top.
Just thinking out loud

OK_Bill · Dec 9, 2014

mellow said:
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?

Yeah, same temps you're seeing. But measured flue temps are very dependent on how far up from the flue collar they're taken. Right at the collar with CAT around 1000-1200 the flue collar (a casting) will be 600-650. A foot above that, flue surface temps running 500. Another foot, and drops another 100F. These all measured with a non-contact IR gun.

I'll be sticking another 4" thermocouple in the flue for reference, instead of the IR gun. Then we can record how much heat is lost up-stack and tweak for better efficiency.

WES999 · Dec 9, 2014

That sounds like a really interesting project. I have posted this before but you may not have seen it.

http://s1321.beta.photobucket.com/u...t=3&o=3&_suid=1360889680009022424730311166158

This is my automatic air controller, it used a temp controller and timer to actuate a HVAC damper controller.
It works quite well but is somewhat limited as to what it can do, it will only close the air control based on flue temp.

I would like to make a Arduino based controller capable of more functions, I actually purchased an Arduino LCD, TC amp etc some time ago, but never really spent the time to learn to program it.

I wonder if you might share some programming examples with me? That may help me get going again on my controller project.

OK_Bill · Dec 9, 2014

Hey Wes - absolutely I'll share whatever will help out.

Pretty interesting rig there - are those PID box controllers? The motor controller sounds heavy duty! What's the alarm for?

Hoozie · Dec 9, 2014

Sounds like fun. I guess my idea for a damper controller for my 30 has already been done

<-- embedded hardware/software guy checking in

ja_cain · Dec 9, 2014

Awesome thread! Will be keeping an eye on this one.

turbojoe · Dec 9, 2014

It looks like tube stoves benefit alot from this.
Should be interesting to see it on a cat stove. Hard to beat the heat delivery they already have.
Stay tuned..

weatherguy · Dec 10, 2014

turbojoe said:
It looks like tube stoves benefit alot from this.
Should be interesting to see it on a cat stove. Hard to beat the heat delivery they already have.
Stay tuned..

How about on a Blaze King, if something could control the air towards the latter half of the burn where it could automatically increase the air you could really level out the burn even longer than it does currently.

mellow · Dec 10, 2014

I fail to see how people would want to extend the burn time on a BK? The bimetallic coil already controls the air intake for extending the burn. The only thing I could see to automate would be loading the wood

turbojoe · Dec 10, 2014

weatherguy said:
How about on a Blaze King, if something could control the air towards the latter half of the burn where it could automatically increase the air you could really level out the burn even longer than it does currently.

Stay tuned, am working on a Blaze King project now. I plan to leave the BK t stat untouched, Am working on a manifold with a throttle body. This will allow air control in the OAK. This way i can use either control, or both :0

OK_Bill · Dec 10, 2014

UPS delivered enough of the hardware yesterday for me to get started writing code - yeah! And then I got lucky on Craigslist where I found a pristine little Omega CL23A temp calibration unit. With this, I can calibrate and verify the accuracy of all the thermocouples I have. Good to have accurate data! Still waiting for Omega to ship the thermocouples - they're custom building one of them - might be another week for that box.

Please feel free to chip in with your ideas and suggestions: I'm a NOOB to burning with wood & running a wood stove - and now I'm writing code to control two separate air feeds... you see the problem :eek:

Its kinda like a student pilot designing software for an autopilot - there will be issues with that!! Hopefully I don't do anything that gets my VC Encore airborne!! :eek:

mellow · Dec 10, 2014

I would find other projects like this and dig through the code to see how they handled it.

http://hackaday.io/project/786-arduino-wood-stove-controller

OK_Bill · Dec 10, 2014

I missed that one - great point out there! Some good ideas from this guy.

WES999 · Dec 10, 2014

OK_Bill said:
are those PID box controllers? The motor controller sounds heavy duty! What's the alarm for?

One is PID capable one is not, but both are set to ON/OFF control.

The way it works is when flue temp reaches 875 ::F

, timer runs damper motor for 3 sec, closes air about 1/2 in, wait 20 sec, if flue temp is still above 875 ::F

, close air another 1/2 in, repeats until flue temp is under 875 ::F

. The other controller measures stove top temp, turns on blower when stove top is over 675 ::F

. Alarm is on when flue temp is over 875 ::F

. There is a alarm silence button.( resets when temp falls below 875 ::F

)

ControlFreak · Dec 10, 2014

Hi Guys,
I'm the Dan that several posts have referenced, and the developer of the SmartStove(TM) control system. I think it has been about 2 years since the last time I posted on hearth.com, or even checked it. It's very strange that I would come here tonight and find this thread on the first page.

I deeply appreciate all the kind comments I have seen here, so I thank you all for that. Last November truly was a great honor to be able to participate in the Wood Stove Decathlon and to meet the hearth.com moderators and also see Craig Issod again, and to bump shoulders with a lot of experts in the wood stove industry.

OK_Bill, I wish you the best of success with your experimentation. I'm sure you'll end up with a very fine-running stove.

Christmas blessings to you all,
Dan

begreen · Dec 10, 2014

Welcome back Dan. It's good to hear from you. Hope you and family are doing well.

OK_Bill · Dec 10, 2014

Howdy Dan - and dittos from one Entrepreneur to another. As I said earlier, my intent is not to commercialize my effort in any way. My aim is to improve the operation of my stove, learn a few new things along the way and have fun doing it all here on the forum.

I'll be glad to share any/all of my research, techniques, failures and successes at the drop of a hat. Just PM me or whatever, and I'll help as much as I can. You're a true trail blazer in the field - many have and will continue to benefit from your efforts.

Best Wishes,
Bill Wightman
OKC, OK

xman23 · Dec 10, 2014

I met Dan in DC. Being a embedded control designer, I had a lot of interest in what he had built. Dan explained in detail his hardware and software design.. As I recall he had a PI closed loop to regulate the primary air control. He had the ability to log and plot the stove sensors and output. Maybe Dan can explain the pro's and con's of what he built.

turbojoe · Dec 10, 2014

ControlFreak said:
Hi Guys,
I'm the Dan that several posts have referenced, and the developer of the SmartStove(TM) control system. I think it has been about 2 years since the last time I posted on hearth.com, or even checked it. It's very strange that I would come here tonight and find this thread on the first page.

I deeply appreciate all the kind comments I have seen here, so I thank you all for that. Last November truly was a great honor to be able to participate in the Wood Stove Decathlon and to meet the hearth.com moderators and also see Craig Issod again, and to bump shoulders with a lot of experts in the wood stove industry.

OK_Bill, I wish you the best of success with your experimentation. I'm sure you'll end up with a very fine-running stove.

Christmas blessings to you all,
Dan

Good talking with you the other day Dan, look forward to working with your controller.

Merry Christmas
Joe

OK_Bill · Dec 11, 2014

xman23 said:
I met Dan in DC. Being a embedded control designer, I had a lot of interest in what he had built. Dan explained in detail his hardware and software design.. As I recall he had a PI closed loop to regulate the primary air control. He had the ability to log and plot the stove sensors and output. Maybe Dan can explain the pro's and con's of what he built.

Cool. I've done enough work in various engineering capacities, but embedded control isn't my forte. The strangeness of this attracts me. You may get a PM or two in the future...

My current feeling is that I need to make sure the timing/sensitivity of the CAT control and STV control loops are tuned correctly. I have a notion at this time that the CAT can and will react much faster than the stove body, which has significant thermal inertia.

OK_Bill · Dec 12, 2014

Slogging through hardware / software integration.

I wanted a neat way to bus the thermocouple (TC) data to the microcontroller. I found a superb little breakout board that does just that... serial bus data feed where each TC has its own i.d. on the bus. Its called the MAX31850. One wire for read/write/addressing. These can be daisy-chained together - as many as you want! I'm planning on 4 TC's in this build, but who knows, I might want more.

Just got notice that Omega has shipped the really high end TC's I ordered. One of them had to be custom built to my specs, which took more time. These 4 TC's will account for roughly 1/3 of the total project cost. The MAX31850's aren't cheap either - at 15 bucks each they account for about 20% of the total cost.

So for those who're watching the thread - I'm right at the point that I know will take the most time: hardware integration. Writing code that will make it all work together in the way I want. So it'll be a few days - maybe even a couple weeks before I have more to report.

I'll post a few pics of all the stuff bread boarded up on the bench when I get to that point.

OK_Bill · Dec 17, 2014

As promised, here's a little pictorial update. We're mostly past the "breadboard" phase as I've already tested and begun soldering all the components in place.

HOWDY from OKC! As you can see, I do a little RC flying.

Here's the little critter: On the left I've stacked a MiniSD card reader on top of a microprocessor (Arduino Uno) to keep the footprint smaller:

On the right side there are 4 thermocouple drivers, and a little home made power supply to drive the servos. The 6 pins on the bottom right corner of the white board are the servo connectors.

I still have to put all the code together, and add the box-lid stuff: LCD display, a rotary encoder, and a couple LED's. We'll approach a first test drive with a simple data-logging run. See how that looks. Still haven't written any of the menu control code, or any of the feedback logic but that will come after it gets boxed up.

Still working ...

mellow · Dec 17, 2014

Can you post a pic of the custom made thermocouple?

OK_Bill · Dec 17, 2014

Sure - it will be here Friday... standby one...

Prichan · Dec 19, 2014

OK_Bill said:
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...

I usually just put wood in my stove and burn it to create heat. Simple process. I have a new VC Encore and love it. VC's get a bad rap but in my eperience with them over the years so far so good.

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