Hacking your pellet stove.

[bcarton]

I'm noticing some interest lately in either remotely controlling a stove, or digging deeper into a stove's settings. A couple of members have expressed interest in accessing the service connections (usb, DB9) that some stoves have.

Instead of modifying a stove's existing programming (which I don't encourage) I would really like to see someone come up with a generic stove controller that could be used to to either drive the cost of engineering new stoves lower, or act as a source of replacement parts for older stoves whose control boards that have become scarce.

Let's face it, there are only so many variables to control here: exhaust blower speed, room blower speed, and auger feed rate. Additionally we need to monitor a few snap disc and maybe a thermometer.

A Raspberry Pi has more than enough horsepower to manage all that. Too bad I'm not in middle school, or I'd be learning how to do that.

The difficulty would be in adapting the interface between the board and the variety of electrical specs that connect to those items being monitored or controlled (motors and snap discs, mostly). Even then, there are only so many variations.

So there's my great thought for the day. Maybe some day someone will run with it and make hundreds, maybe even thousands of dollars. If I had programming skills, I would tackle it.

 

[Vinnie 1965]

In it for the replys

 

[STANG302]

Agreed it would be cool to have an upgrade kit for older or low end pellet stoves. I would add one more feature. A true thermostat control like what quadra-fire has. One that will shut the stove down once temp is reached and fire it back up when calling for heat.

I hate stoves like mine that will only throttle down and waste pellets over heating the room.

 

[rona]

You should own a Bixby which are no longer made. The last ones were built 2008 but you can plug your laptop into it and install updated software, You can use Bixchek to go over 47 different functions of the stove and lastly you can turn it on or off or adjust the settings via a smart phone or a different computer. You can adjust the fuel, exh fan speed and convection blower speed for each heat setting if you wish.
The Quadrafire AE by the way it is designed has to shut off to dump the pot then will restart but the owner can't do much adjusting other then using whats available.
You can program it to turn off or on via a thermostat but doing so will wear out the igniters faster same as any other stove. As a example if you live near sea level you can adjust the fuel and air ratio for that altitude but if you moved to Denver those settings wouldn't work very well. So you can change the settings to make the stove run better at that higher altitude. Much like the old days when carbs had to be adjusted for the higher altitude.

 

[pellet]

This might be a starting point:
http://www.electro-tech-online.com/...ews/24165-pellet-stove-controllers-print.html

 

[pellet]

Here is another:
https://www.hearth.com/talk/threads/custom-control-schematic-for-older-pellet-stove.72519/

 

[STANG302]

Yes, I loved the thermostat feature on my old Quad. But hated the preset burn settings (L,M,H).

 

[bcarton]

Great replies here - thanks! Pellet - those links are exactly what I was thinking of. And Rona - so that's the deal with the Bixby? I've seen a couple for sale recently, not cheap. I don't think my Yamaha receiver has 47 functions, that's incredible.

 

[Bioburner]

Bixby exec's go charged with mail fraud. Something to do with coal gasafication and the Chinese.

 

[1Mechanic]

Agreed it would be cool to have an upgrade kit for older or low end pellet stoves. I would add one more feature. A true thermostat control like what quadra-fire has. One that will shut the stove down once temp is reached and fire it back up when calling for heat.

I hate stoves like mine that will only throttle down and waste pellets over heating the room.

I have a Breckwell p23 and I have the option to Go thermostat on/off but sometimes for unknown reasons it will not restart. Igniter glows fine but will not start the pellets. So I am trying the High/Low Thermostat setting now and yes it does run more will see what is better mode to run in.

 

[yulester]

Has anyone looked any further at this potential project?
I'm looking into creating a Raspberry Pi controller for a pellet stove. Once I find a stove with a shot controller for cheap, I'm gonna play. If anyone has seen similar, let me know.

 

[Ssyko]

https://www.hearth.com/talk/threads...ard-of-sorts-under-30-00.172216/#post-2308335

 

[rona]

Bixby exec's go charged with mail fraud. Something to do with coal gasafication and the Chinese.

Actually much more serious then that they bilked investors out of millions of dollars claiming they had devised a system of reducing emissions from burning coal down to about the same as nat gas. Of course it was a scheme . I doubt they have found the money. Its odd how some people just can't resist the easier illegal ways of getting rich.

 

[Tonyray]

Agreed it would be cool to have an upgrade kit for older or low end pellet stoves. I would add one more feature. A true thermostat control like what quadra-fire has. One that will shut the stove down once temp is reached and fire it back up when calling for heat.

I hate stoves like mine that will only throttle down and waste pellets over heating the room.

U mean like a Harman does or u mean an instant shut down.

 

[Bill A]

A Raspberry Pi would certainly have enough computing horsepower to control a pellet stove, but you will rarely find them used in industrial applications for small machine automation.

They are cheap enough but the problem using them is that you need to interface them to digital inputs such as vacuum proved switches along with digital and analog outputs. All this requires add on boards and the time to write code to interface with them.
Most small OEM's that I deal with will use small PLC's or devices known as smart relays from companies such as Crouzet , Schneider, IDEC, or even Allen Bradley. Automation direct has made an entire business out of online automation sales to small machine builders and integrators.

The advantage with using these is that they have all the inputs and outputs already there to connect all the hardware up to and are industrially hardened.
The disadvantage could be the cost but with the extra money, all that is already taken care of. Additionally all the software functions that you would need to build a fully automated control system are all ready there. Want to try and write a PID loop on your own? For many if not most of these low end units the programming software is free.

One more thing to keep in mind is that human beings must be able to interact with your new hi tech control system and for that most OEM's look for devices with either a text display or perhaps a graphic touch screen. You need to be able to view and change parameters quickly and easily and almost everyone is leaving push buttons and lights for text and graphic displays.

 

[rona]

Great replies here - thanks! Pellet - those links are exactly what I was thinking of. And Rona - so that's the deal with the Bixby? I've seen a couple for sale recently, not cheap. I don't think my Yamaha receiver has 47 functions, that's incredible.

I don't know about all the stoves on the market but sometimes the simpler the better. Its hard to beat the St Croix Auburn for cheap dependable heat . Manual start and manual dump the brick. You have to add fuel so not much extra work to pull and push a couple rods.
Harman is more automatic and gives you two modes of operation. Bixby had it way over the other stoves but was to complicated for a lot of people and dealers who never owned a computer. Funny how things changed. Now we can control the Bixby with smart phone or computer at work if we desire. We can change the software our selves if we want to.
The Quad AE also has software but it is not adjustable .

 

[yulester]

Bill A -

Understand completely.

My reasoning for the Pi is more of the research regarding the settings I want to be adjustable. In my case, I would like to change the computer in my Quadrafire 1200 classic bay to be a bit more user friendly. Within the last couple years, I'm seeing a change in my pellet which I cannot adjust the unit with the current available settings. My gate slide needs to be far more constricted to run, but It's too throttled down for correct startup. If I could leave the gate alone and increase the time between feed cycles that would help. I also need to increase the combustion blower time during shut down. Currently, I still have a huge pile of coals still glowing when the blower goes off, and then it stays in the pot not allowing a startup cycle due to the build up (clinker).

I'm also considering a couple different items. One being a thermal switch just below overheat. When this is triggered, it would increase the time between feed cycles by maybe 10 seconds to bring the burn temp down. Once this occurs, maybe an increase of 7 seconds to stabilize. Might incorporate an O2 sensor in the exhaust as a calibration method.

If you wanted to get even crazier, how about remote thermostat/current operations from a smartphone. Have current operation parameters displayed with a camera in the room showing the unit in operation. How about an automatic shutdown from a battery backup when the power goes out. (Yes, I know it can be done easier than a PI, but add this into the whole process.)

I'm looking for a stove for sale with a bad computer, or even one low enough in price where I can pitch the computer and play. I'm willing to play with a stoker or a top feeder.

 

[rona]

Bill A -

Understand completely.

My reasoning for the Pi is more of the research regarding the settings I want to be adjustable. In my case, I would like to change the computer in my Quadrafire 1200 classic bay to be a bit more user friendly. Within the last couple years, I'm seeing a change in my pellet which I cannot adjust the unit with the current available settings. My gate slide needs to be far more constricted to run, but It's too throttled down for correct startup. If I could leave the gate alone and increase the time between feed cycles that would help. I also need to increase the combustion blower time during shut down. Currently, I still have a huge pile of coals still glowing when the blower goes off, and then it stays in the pot not allowing a startup cycle due to the build up (clinker).

I'm also considering a couple different items. One being a thermal switch just below overheat. When this is triggered, it would increase the time between feed cycles by maybe 10 seconds to bring the burn temp down. Once this occurs, maybe an increase of 7 seconds to stabilize. Might incorporate an O2 sensor in the exhaust as a calibration method.

If you wanted to get even crazier, how about remote thermostat/current operations from a smartphone. Have current operation parameters displayed with a camera in the room showing the unit in operation. How about an automatic shutdown from a battery backup when the power goes out. (Yes, I know it can be done easier than a PI, but add this into the whole process.)

I'm looking for a stove for sale with a bad computer, or even one low enough in price where I can pitch the computer and play. I'm willing to play with a stoker or a top feeder.

If I connect my Bixby to my laptop via Bixchek and using wifi I can see what is happening on my smart phone. I can verify which heat level it is running on. If the thermostat heat level is reached it will be at heat level one idling or between level one up to level six.. I can also adjust the fuel and air on each heat level to compensate for different type of pellets or fuel. If I want to change a lot of settings it is best to do it with the laptop. I can't make it start from being shut down and it has to be at a idle to stay running. A Harrman has the option of OFF and start via thermostat or it will run at a idle. A Quadra Fire AE might be more in line with what you want to do but Quadra fire wont let you adjust the software.

 

[yulester]

but Quadra fire wont let you adjust the software.

- - - - - Exactly

 

[mfenmor]

Has anyone looked any further at this potential project?
I'm looking into creating a Raspberry Pi controller for a pellet stove. Once I find a stove with a shot controller for cheap, I'm gonna play. If anyone has seen similar, let me know.

Workin on it. Give me a minute.

 

[Lordtimothy200]

I am starting to work on my Auburn St Croix stove. Anyone know if a pwm will work to control the voltage if the fan motor?

Currently I am working to get my temp sensor working inside the stove. Hopefully I can get that done this week.

 

[Ssyko]

As long as the motor was designed to work with speed controls, and the PWM is designed for 120vac I would assume it would work.

 

[Bill A]

If the motor is a shaded pole or permanent split capacitor, it should work.
When you say PWM, what frequency are you intending to cycle at?
Most single phase fan speed controls chop the waveform every cycle or at 60Hz.
A solid state relay or SSR would be what you would use to control the motor.

 

[Lordtimothy200]

Looks like the motors are permanent split capacitor at 60hz. The Exhaust blower changes voltage from 85 volts to 98 volts depending on the heat setting.

My understanding (which is limited) the SCR is not a good option for brushless motors. Correct?

Edit: changed scr not ssr

 

[Bill A]

A solid state relay SSR would use either back to back SCR's or a single triac.
An AC motor is brushless, but that term is usually reserved for dc motors with solid state commutation.
The permanent split capacitor or PSC is an induction motor where one of the winding's is connected permanently in series with a capacitor.
The capacitor provides the rotating magnetic field to pull the soft iron rotor around.

If you want to vary the voltage using PWM you can use an SSR to do this. Find one that is a Zero crossing type, that will only turn on at the beginning of the AC cycle. My suggestion would be to use a fairly low cycle time for your output say 1 second or a half second and let the inertia of the motor / impeller smooth out the pulses. The effect would be the same as varying the supply voltage. I've tested this out in the past and it works.

You could also use a paddle fan controller to set the lower run speed and then bypass it with a relay when the auger runs, not as sophisticated as PWM but might work well enough for your controller.