How come modern woodstoves don’t have microprocessor controls?

[VTSR5]

I was fiddling with the bimetallic coil which controls the primary air on my VC WinterWarm (small) last night, and it occurred to me "This is exactly the same primary air control system that my father had on his 1975 Defiant THIRTY-THREE YEARS AGO." It also occurred to me that this idiotic bimetallic coil measures and responds to exactly ONE VARIABLE in the operation of the woodstove. So what gives? Why is there a $400 refractory package/cat combo on my stove, but no $125 microprocessor primary air controller that senses a couple of operating variables and adjusts primary air to maintain some kind of steady state? Why does Pacific Energy think they've cracked the atom with their "Extended Burn Technology" which is nothing more than, you guessed it, A BIMETALLIC COIL!

Don't tell me you don't want to plug your stove in -- mine's an insert and it's already plugged in!

So what do you industry watchers think? I know it ain't the highest tech industry in the world, but why does it seem the woodburning stove industry wants to be constantly back on its heels waiting for the EPA to club them over the head with some kind of "That's impossible to attain" regulation to get them take the obvious next step?

 

[webbie]

There are some...I think!
http://www.nestormartin.be/en/burn1_en.php
And we actually have an inventor on the forum who has a patent on a unit which can either retrofit or be built into modern units.
http://www.inveninc.com/

 

[begreen]

I'm guessing the number one reason is cost. Second might be concerns over power outages and random electronic failures. Then there is the KISS factor.
For many, the simpler to operate and maintain the better.

 

[fossil]

Super-insulated containment & perhaps the requirement for an additional cooling fan...or remote placement of the processor...and then, what would it control? If the system is going to be microprocessor controlled, then it's going to need a power supply and signal amplifiers and servo motors to position dampers or something. Not saying it couldn't be built, it most certainly could be...but for a woodstove, it just might all be an unecessary complication and expense. A simple bimetallic device responds to temperature change with no need for any of that. Rick

 

[moondoggy]

i sell microprocessors/ ic's .... temps are a little extreme for a stove, but i suppose it could be done. i wouldnt buy it.
besides my air control is controlled automatically but the same little coil of metal used in a thermometer... moves by itself, temp stays constant, cant be any easier for ME to replace should it fail.
i see no real need for electronic control..... unless it could load the wood for me!

 

[Adios Pantalones]

More to break, go obsolete, fail in a power outage, it's harder for the average homeowner to service by themself, it's more expensive, and current dumb epa stoves give great performance already. It really aint broke.

 

[webbie]

Sounds like some luddites here - after all, who the heck would put microprocessors in, for instance, my kitchen stove and oven? And diswasher? And in that horrible environment that is my car engine? Heck, there are now chips in Hallmark greeting cards!

Such a module could eventually be made to power itself....

I think the nestor martin unit is cool.

 

[begreen]

Guilty, we just got a cell phone plan... with great reluctance. But our oven and pellet stove electronics have failed due to rural crappy power, so now I have a full UPS on the stereo and home theater components. Technology doesn't come without dues.

 

[Adios Pantalones]

Plus- when machines gain self awareness, I'll never be able to keep that thing lit

 

[InTheRockies]

Wouldn't want one, if I did I would have gotten a pellet stove. It's a part that will definately fail, probably sooner that most parts on a modern, EPA stove (given the turmoil of the economy; I'd be worried about non-generic parts for orphaned products as companies begin to try to survive a possibly deep recessionary period); it consumes power, making it less "green" and cost effective; it isn't really needed. Computer chips are not the end-all for products. This is one application where they don't make sense.

 

[VTSR5]

More to break, go obsolete, fail in a power outage, it's harder for the average homeowner to service by themself, it's more expensive, and current dumb epa stoves give great performance already. It really aint broke.

Isn't this pretty much the same sentiment everyone had back in 1980 about the coming EPA stoves? I submit that it is broke, it just doesn't seem broke until you've been dragged kicking and screaming to some new better place. I can't be the only guy that remembers that pre-EPA stoves were simpler, cheaper, easier to fix, but not many would go back to them now. And those virtues didn't protect them from obsolescence.

I enjoy heating with wood, but I have to babysit my stove(s) for the first hour after loading, simply because the bimetallic coils controlling them are too simple a solution to the somewhat complex problem of determining proper air fuel mix in the dynamic environment of the firebox. Some days, I enjoy that duty. But as far as I'm concerned, primary air control is an UNSOLVED PROBLEM that we have all simply learned to live with.

 

[fossil]

There are a lot of apples and oranges being tossed around in this short thread. If you look at something like an internal combustion engine in a vehicle, and you're thinking about how to bring the old mechanical fuel injection system, with its 3-D cams and other internal intricacies into the modern era, then yes...microprocessor-controlled electronic fuel injection is the (current) solution. Primary air control on a woodstove is a problem orders of magnitude simpler, and it may not warrant as elegant a solution...yet. Rick

 

[Adios Pantalones]

What exactly do you hope to improve? How much better than epa standards do you want to get? My current stove has no coil controling temp anyway, so maybe that in itself is not done as well as it could be- so I'd like to hear what you'd like to see it do.

I'm all for technology- believe me. I'm in a high tech job, in a high tech career, and like electronic toys about as much as anyone- but when it comes to something important that's exposed to potentially corrosive combustion gases and controling a stove in the house where my family sleeps- it should be reliable as heck (and setting an air control myself and leaving it- generally very reliable).

Other thermocouple or thermopyle type pyrometers are no more reliable than most bimetalic strips in this application, IMO.

Oxygen sensors (like oxyprobe), particle sensors, etc- what will their output exactly do? They'll only probably control damper/air settings... put in wet wood and they'll allow in air until you bump into the overfire issue, and they have effectively not done that much. Put in dry wood, and eally you're back to temp control.

Further- I'm surprised that you have to babysit your stove for an hour. I don't remember that the pre-epa stove was any easier to handle (quite the opposite, actually, with the smoke and creosote that I... fondly remember)- current non-cat stoves are super easy! There's nothing extra besides secondary burn tubes- and they are no trouble whatsoever.

Whatever they do- if the failsafe condition is carefully considered and goes back to manual easily, then it will be safer to implement... but it's still not the sort of thing that I want the first generation of

 

[Jags]

What the heck would I do, if not messing with the controls? Sure, I can set the sucker and walk away (which I do alot), but sometimes I wanna play with the controls.

 

[precaud]

I have a Nestor Martin that does what you describe. I've reviewed it in a previous thread:

https://www.hearth.com/talk/threads/14421/P15/#158948

 

[kd460]

You can keep those microprocessors! Give me simplicity. Someone mentioned a standard cooking stove. My "microprocessor" on my stove is on the fritz. The basic function of the stove is fine, but the processor is going south. So, the processor or the $20 bucks worth of resistors, diodes and chips will make me get a new stove? Or a service call for at least $100 and how much for replacement/repair parts? It is less than 10 years old and it is the most expensive stove I have ever owned.

My parents have a stove without a processor, with out electronic igniton, with out the digital computerized read out. It is almost 50 years old. It works just fine. With power on or during a power outage. Still cooks food just fine!

Give me an old 1970 chevy 3/4 ton pick up any day! No diode or chip is gonna go bad in that baby! KD

 

[cmonSTART]

I would absolutely give it a try. But only if there was a simple mechanical control like there is now still hooked up.

 

[VTSR5]

What exactly do you hope to improve? How much better than epa standards do you want to get?
Other thermocouple or thermopyle type pyrometers are no more reliable than most bimetalic strips in this application, IMO.

Further- I'm surprised that you have to babysit your stove for an hour. I don't remember that the pre-epa stove was any easier to handle (quite the opposite, actually, with the smoke and creosote that I... fondly remember)- current non-cat stoves are super easy!

Thanks for your thoughtful comments.

Improve: Reload at 10 pm and walk away, collapsing into bed. Reload at 6 am and walk away to get two children fed and ready for school, then hustle out the door to earn a living. Now at 6 pm, turn off the microprocessor control, sit by the stove with the paper and a beverage, and manually dial in the burn -- that's the time I really enjoy the duty!

EPA: I don't think the EPA is done raising the bar on stove emissions. And if it's not the EPA, than it's state and local jurisdictions. I don't really care so much about my stove being cleaner than required, my question was really more along the lines of, why haven't manufacturers in this industry laid more groundwork here in automating stove controls -- it seems obvious to me that they must go there eventually.

Reliability: Agreed, but my problem isn't with the reliability of the bimetallic coil. I find them highly reliable, just not very sophisticated.

Babysitting for an hour: Well, maybe not constant babysitting, but pretty regular attention for an hour or more after reloading in order to bring the temp up for the cat, but not up too high. In my case, after a reload, to properly engage the cat requires bringing the stove up to temp in updraft mode, then gauging the internal stove temps, then closing the damper and adjusting the primary air. If I want to reload then shut the stove down for a longer burn (as is necessary in the morning and late evening) without snuffing the cat, this is a two or three step adjustment taking a couple more visits over an hour or so to close the air in increments from a very hot stove to say medium hot. Since I have never used a modern non cat stove, I don't know if multiple steps are required in shutting down for long burn on such a stove. Please comment.

My point is simply this -- think about how much you use the glass in your stove to analyze the combustion conditions in order to make a decision in setting the primary air at the front end of your burn cycle. The bimetallic coil can't do that, it can only sense the temperature of the air near the stove in one specific area. But a microprocessor with a couple of sensors could come a big step closer to automating most of those decisions. Yeah, I don't want the first one off the line either, but I do wonder why there are only one or two examples of such technology in a field crowded with competitors each seeking to distinguish his own black steel box from the other guy's black steel box.

 

[Jags]

Hmmm... I don't get what all the fuss is about.

Jags morning routine:
Wake up, itch and scratch.
go downstairs.
Pile coals towards front of stove.
Throw a hand full of smaller stuff on coals
throw big stuff on top
Open air
take shower
close air down for day long burn.

Repeat for evening burn.

One slide lever.

Easy.

 

[Hogwildz]

Sounds like you need a pellet stove.

 

[VTSR5]

Sounds like you need a pellet stove.

How cruel! I simply can't live in a world of small-bore affordable vent pipe, easy through-the-wall installation, and tidy palletized fuel.

Hey, if my post is starting to sound like a complaint, that is because I have been asked to explain in detail what I think could be improved. It's an exercise in imagination.

 

[RedRanger]

Didn`t anyone notice that VT is running a cat-stove?? Perhaps if he experienced the ease of a new non-cat he might find it a little easier--and quicker ;-)

 

[EddyKilowatt]

Primary air control on a woodstove is a problem orders of magnitude simpler, and it may not warrant as elegant a solution...yet. Rick

I tend to agree with this. A bimetallic coil (or other simple mechanical temperature sensor) can do a pretty good job closing the basic control loop in a solid-fuel stove -- once the fire's burning well -- and be simple, cheap, and stone-axe reliable (if well designed). Any draft-powered burner -- like all our stoves are -- tends toward instability, either running away or dying out unless "something" keeps an eye on the draft. A simple one-variable control system does fine at this.

But as anyone who's fired a wood stove will tell you, there's a lot more to it than just controlling the burn rate. With every fuel load, you need to get the burn established, encourage flaming combustion and especially secondary combution during the first half of the burn, keep an eye on the smoke from your stack, then stoke the firebed and encourage full burn of the coals (ideally without secondary air). I suppose you could do all this with a mix of optical and thermal sensors, or (heaven help me) some image processing software... but really, evaluating how "well" a wood fire is burning requires a lot of judgment that (it seems to me) would be pretty difficult to reduce to a rule set.

So, maybe we'll see an electronically-controlled stove some day, and I'll certainly be interested to see how it works when it arrives... but I don't think it will work a whole lot better, overall, than a simple one-variable control loop that's mechanically actuated.

Willing to be proven wrong on this though!

Eddy

 

[Valhalla]

A bi-metal spring thermostat is all that is needed. Keep it simple, yes KISS as we call it, in the high temperature area of a wood stove.

 

[fossil]

We're gonna have to start focusing on shielding and insulation here, because the space that houses the computer and associated electronics for the stove controls should be in close proximity, but air-conditioned. ;-P Rick