I was tired of fiddling with the damper on my Jotul F600 (Firelight), so I automated it using a motor and a micro-controller. I have no desire to produce and sell this, but just like to automate repetitive tasks around the house and learn new stuff!
The logic allows for different modes:
It decides airflow changes based on the difference between current and target temps (stove and room, depending on mode) and, just as important, it considers the temp change rate. This allows for a "soft landing" instead of spiking above/below targets (which happened at first).
Also, it seems that the airflow rate is not proportional to the lever position. For example, the change from 1-20% open seems to produce a greater effect on the combustion than 80-100%. So, I wrote a function to translates desired airflow change to a lever position by weighting the lower increments.
I think there is added efficiency in the middle 3 modes, because it fires over 380F on start-up (which seems to burn all the fumes) and the secondary burn carries temp for a good wile after tightening-up. Also, if the Room Temp calls for a stove temp of 340 to 380, it will round up to help limit smoldering. However, the greatest benefit is I don't need to attend it - the system does what I would do if I paid attention to it.
It's a prototype (i.e. ugly-looking) for now. The motor will live under the stove next year (instead of duct-taped to the cat condo!), by routing the draw cord with a tiny pulley. I'll probably glue-gun the electronics together and put into a plastic box at a safe distance. I control the primary airflow now, but might try dampening the general intake port to compare that technique and to improve aesthetics.
I've lurked for a while, but this is my first post. I expect if anyone likes this stuff besides me, they would hang out on this forum!
The logic allows for different modes:
- "Manual" - control lever with the app's slider bar
- "Standard" - get up to temp, limit air flow and pat down gradually until new load
- "Overnight" - up to min temp then close air way down
- "Room Temp" - keep room at a target temp
- "Stove Temp" - keep stove at a target temp
It decides airflow changes based on the difference between current and target temps (stove and room, depending on mode) and, just as important, it considers the temp change rate. This allows for a "soft landing" instead of spiking above/below targets (which happened at first).
Also, it seems that the airflow rate is not proportional to the lever position. For example, the change from 1-20% open seems to produce a greater effect on the combustion than 80-100%. So, I wrote a function to translates desired airflow change to a lever position by weighting the lower increments.
I think there is added efficiency in the middle 3 modes, because it fires over 380F on start-up (which seems to burn all the fumes) and the secondary burn carries temp for a good wile after tightening-up. Also, if the Room Temp calls for a stove temp of 340 to 380, it will round up to help limit smoldering. However, the greatest benefit is I don't need to attend it - the system does what I would do if I paid attention to it.
It's a prototype (i.e. ugly-looking) for now. The motor will live under the stove next year (instead of duct-taped to the cat condo!), by routing the draw cord with a tiny pulley. I'll probably glue-gun the electronics together and put into a plastic box at a safe distance. I control the primary airflow now, but might try dampening the general intake port to compare that technique and to improve aesthetics.
I've lurked for a while, but this is my first post. I expect if anyone likes this stuff besides me, they would hang out on this forum!
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