Fine Tuning the pellet burn

[jazzmonger]

Controlling the burn of a fire pot in a pellet stove is a lot more complicated than it sounds. These are all factors

• Auger on time -controls how much fuel is delivered
• Auger off time - how long between deliveries
• Combustion fan - forcibly feeds air to the fire
• Stoking function - when the fire is about to go out, stoke it with more fuel.

Basically it's all trial and error. The idea is to lower the burn temperature so the stove just cruises along and doesn't go out, and provides enough heat to warm the room it's in without making the room too hot.

The whole reason I did these mods is because from the factory, the lowest burn setting is P4 in ECO2 Mode and that isn't low enough to burn continuously and not raise the heat level in the room to 80. ECO1 Mode stops and restarts the fire and that wastes pellets and burns out your igniter once or twice a season. Yup, and it's a pain and expensive to replace.

So, by using ECO2 mode and tweaking the burn params just right, everything works and works really well. If the room gets too cold (4 degrees below the set temp), the stove automatically kicks the stove into whatever power level it's set for P1-P4, P1 being aggressive heating, P4 gentle heating. Once it heats up to set temp +1 or 2 degrees, it goes back into "Ultra Low Power". The savings on pellets is remarkable.

A graph of things working really well is below

you can see the stoking sensor only occasionally had to stoke the fire and after tweaking the auger on/off times a little after 11:00 by just 0.1s higher the fire stays lit.

This next graph shows the fire being stoked a lot. Not enough pellets are being fed to the stove. That is until I realize it and make an adjustment around 8:30am

It's very slight adjustments once you find the right range. My params that accomplish this balancing act are:

Tis is about as good as it gets - very infrequent stoking.

The original burn params are here. The Ultra Low setting is almost half of what P4 is:

I also adjust the settings on the front panel display for P1-P4 and I set S=20 for all those levels. This ups the combustion fan speed. You can also adjust the F value to increase or decrease the room fan.

IMPORTANT: I also set the cleaning params to 20s every 1 min - keep cycling thru the settings options and you'll find that setting. This raises the combustion fan speed just slightly to come on for 20s once every minute and keeps the low burn clean and going strong.

Your settings will vary, but these are good starting points. Once you find the right mix, you shouldn't have to make further adjustments unless you switch pellet brands or make other mods that affect the burn.

[jazzmonger]

2023 Update:

In my quest to get the burn to go even lower so the stove put off less heat and uses fewer pellets, Im now using the following settings:

so on time went from 1.5s -> .9s and off time went from 11.8s -> 9.3s. Stoking temp was also lowered.
This resulted in lowering the burn pot temp by another 20F, and still results in a stable fire. The stove has been burning for almost 24 hours and I've used about 1/3 bag of pellets, perhaps 15lbs. Minimal stoking of the fire is optimum.

[jazzmonger]

a perfect graph of settling into winter!