I want to hack my pellet stove

I have an Ashley 5501S I bought last year. I had to buy based on footprint, which meant I got screwed as far as maintenance, reliability, forum information, and controls all go. 

The controller is a separate unit that needed plugged in to a wiring harness. But instead of having convenient, separate, "feed" and "fan" controls, they're combined into one setting button, which means unless the physically adjusted damper is set perfectly, it burns like E36 M3. There is a physical pellet feed adjustment, but it's a sliding plate, and turns out if you use it to lower the pellet feed, the pellets will jam the gap and it will shut off because it's not getting feed. 

What I want to do is to separate the pellet feed auger and blower fan controls. And/or automate the damper adjustments somehow. 

I've been doing some digging and have found hundreds of projects involving pellet smokers, but very very little with regards to an actual pellet stove. Some custom firmware for a few random models, and a 5+ year old write up on making a Pi controller, and One guy with my model stove whose done some modification on his own. 

I don't have the best soldering skills, and most of my electrical engineering knowledge went out the window shortly after the classes were over 16 years ago. 

But it stand to reason that the wiring harness connects the controls to the system, and there are wires from each part individually that get grouped to the controller. 

Could it be as simple as finding the right wires and putting potentiometers on them? I'm hopeful but not optimistic because of the electric start and not really knowing how it decides if it's starting, running, empty, or shutting down. 

There are some physical changes I need to make to the stove, like drilling out the holes in the burn pot for better airflow, heavier duty gaskets to stop air leaks, but from talking to people those will only get me so far. It'll still feed stupidly high, half burn or overflow perfectly good pellets, and push out loads of fly ash. 

The damper is obnoxious. There's an intake tube on the back of the stove, with a lever to control the hole size. Simple, right? Except there's a half inch of dead zone when you move the lever before it actually moves the restriction in the airway. Open it too far, and it burns everything, don't open it far enough and it leaves hard clumps of ash and overflows with half burnt pellets. Figuring out some way to servo control it to find the right AFR is beyond my skill set, but might be easier than creating a whole new control panel. 

at least they were nice enough to include this in the manual

Fix the mechanical play in the damper first. Then small movements that will be controllable with a servo become possible. Maybe not necessary once it has no play in the mechanism. Otherwise you can do individual control by picking up the wires from the top of the control board. You may need to "replace" the disconnected component with a resistor. Determine what ohm by measuring the component and matching the resistor to it.

A friend did this using arduino, although he didn't replace the stock control unit, he put controls onto the damper, the feed, etc.   He used a 3d printer to make up brackets to hold little servos, and then wrote software to use some thermocouples to monitor it and make little adjustments to the damper.  

In your case, it looks like you want to add the equivalent of a piggy-back ECU, so the easiest way I see is to make it a small controller that will hijack either the fan or the feed so that the ECU think it's sending out whatever code, and you're hijacking it.  I'd probably start with checking the fan, and hope you get lucky that it's a simple resistance change when the ecu tells it to change, however, I'd expect on anything modern that it's actually using PWM (pulse-width modulation), which makes it a touch trickier to control since you can't just slap a potentiometer on it, but not too much harder with an arduino. 

TurnerX19 said:

Fix the mechanical play in the damper first. Then small movements that will be controllable with a servo become possible. Maybe not necessary once it has no play in the mechanism. Otherwise you can do individual control by picking up the wires from the top of the control board. You may need to "replace" the disconnected component with a resistor. Determine what ohm by measuring the component and matching the resistor to it.

And I totally agree that you need to get rid of the slop in the system.. That's always REALLY hard to do a "my first electronics poject" with mechanical slop to deal with...