DIY Pellet Fed Boiler Is Hot Stuff


[Firewalker] has designed a great pellet burning boiler (translated). Wood and biomass pellets have gained popularity over the last few years. While freestanding stoves are the most popular method of burning the pellets, [Firewalker] went a different route. He’s converted a boiler from what we assume was oil to pellet power. An Arduino controls the show, but don’t hold it against him. [Firewalker] is just using the Arduino as an AVR carrier board.The software is all written in C using AVR studio. The controller’s user interface is pretty simple. A two-line character based LCD provides status information, while input is via buttons. Once the system is all set up, thermostats are the final human/machine interface.

Burning pellets requires a bit of prep. A cleanup of the burn chamber must be performed before each burn. The AVR is programmed to handle this. Once the chamber is clean, new pellets are fed in via an auger system. The burner is monitored with a standard flame sensor. When the fire is up the pellets feed in until the boiler gets up to temp. Then the system enters a standby mode where it feeds in just enough pellets to maintain the flame. When the thermostats stop calling for heat, the whole system shuts down, ready for the next burn.

33 thoughts on “DIY Pellet Fed Boiler Is Hot Stuff

  1. Thanks you guys!

    You did a pretty good translation!

    I am in the process of releasing the source code for it. Many people are asking for it. Although it would require many changes for a different system.

    I will also have to redraw the schematic (I am away from the system it is saved).

    1. The flame only goes of when the user turns the system off or when the desired temperature of the house is achieved. Igniting the pellet is a mater of 30 or so seconds.

      I believe using a PID controller would not offer any big advantages. For example the thermal energy given by the pellet is heavily dependent by the pellet it self and the weather conditions (humidity). Even pellet from the same company will burn differently. Calculating the correct amount of air/fuel you have to feed would require work we were able to offer.

      One thing I wanted to implement was a particle (smoke) detector to the exhaust in order to reduce the fuel flow in situation of smoke creation. I abandon it because pellet burns really clean. Only bad quality pellet produces smoke. It contains plastic, soil, dirt and other nasty things.

  2. Although pellet burners are available here in maritime NZ, folks are wary of being locked into a single fuel source, as ONLY pellets can be burned & their retail prices are pretty high! Far more crucial however is that an electric pellet feed is needed. Power cuts (which are exceedingly rare here) hence mean NO HEATING AVAILABILITY. Argh- extended snowed in/lines down wintery conditions in continental regions could make a pellet burner hence a useless millstone…

      1. Buying a pelletizer in single quantities cost about $10000. That locks you into suppliers. Pressure required to form the pellets is above the pressure/volume hand cranking is capable of producing.

  3. Reminds me of when I had to keep a coal boiler running. Clinkers kept shearing pins in the ash auger. It eventually ate the gearing in the auger system and I had to manually shovel out the ash and clinkers every two hours.

    1. Pellet doesn’t produce large amounts of ash. You only have to clean the boiler once or two time a week. Just a bucket of ash.

      The big problem is when someone uses bad quality of pellet. It contains soil in order to make it heavier. The big temperature in the burner transforms the soil into glass like mass that is really touch to clean.

    1. The writeup’s disparaging of Arduino is sort of a tongue in cheek joke.
      There was a time where seemingly every hack was involving an Arduino in some way. Even in applications where it was grossly over/under-specced for the task at hand. This resulted in some backlash / strong opinions for a time in the comments here at hackaday. So now the editors poke fun at the community a out it every once in awhile.

      We went through the same thing with LEDs in hacks and one particularly annoying comment troll for a time.

      I genuinely believe the editors and readership of hackaday don’t have any real dislike of arduinos, but some of us might wonder “why use an Arduino, when a bare AVR or PIC etc. would work as well?” From time to time.

  4. Back in the 1980s I had a house in New Jersey that had been built in 1930, with steam radiators and a boiler that had originally been coal-fired, but was converted to oil. I assume dealing with pellets is almost as annoying as coal :-) The catch to an oil burner is that if the electricity goes out, the pump that blows it into the burner chamber stops, but there really wasn’t a practical way to have both oil and coal support at the same time.

      1. It depends on the type of coal burner. Our house originally had what was called an ‘octopus’ furnace that was convection based. Large pipes, about 6-8″ diameter, snaked throughout the house carrying warm air as it rose from the burner in the basement. Inefficient, but it ran without electricity.

      2. You’re already working with steam, I don’t see why you couldn’t use steam pressure to run the pump or blower. Of course you’d need to ‘bootstrap’ it and feed it with water, but we had to do that anyway with our old boiler/radiator system.

        I remember the weekly boiler bleed – go down in the basement, put the pail down, put on the safety goggles, and pull the lever. Hot rusty steam everywhere! Good fun and just what a 13-year-old wanted to do before hiking to school in the snow.

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