Exactly what is the pellet feed rate control used for?

[RKS130]

I have been running my new Accentra FS with the pellet feed rate at 2 to 2 1/2. On another thread a comment was made that lowering the feed rate does not conserve pellets and chokes combustion. If this is so, why have a control?

Will one of you guys who understand these things fill me in? I have been running the stove on room temp set midline to low; feed rate at 2 to 2 1/2; temp at 64/65 (nighttime) and 70 (daytime). I have been burning American Wood Fiber pellets from HD (3.94/bag) with seemingly good results - but my lack of experience may cast doubt on that opinion.

The stove is located in a foyer at the bottom of the stairs. It is between the front door and the double wide entry to the main room on the first floor. The roughly 1500 sq. ft. house [two story, stone and brick exterior, plaster over lathe interior; built 1910 with no insulation] is comfortable, so I guess the old saw "if it ain't broke don't fix it" applies. BUT, like everyone else I want to maximize my heat at the lowest cost/use of pellets.

Any thoughts?

 

[newf lover]

Read this link. I think it gives a pretty good explanation.
http://www.squierlumber.com/pdfs/troubleshooting-guide_operation-principles.pdf

I just had to turn my feed rate down because I noticed some smoke coming from my outside vent. I'm using a very dense pellet and was just experimenting with increasing the feed rate to see what would happen. Duh, it did the same thing as last year. I just turned ti down from 3 1/2 to 3, no more smoke.

 

[lbcynya]

Read this link. I think it gives a pretty good explanation.
http://www.squ.com/pdf/troubleshooting-guide_operation-principles.pdf

I just had to turn my feed rate down because I noticed some smoke coming from my outside vent. I'm using a very dense pellet and was just experimenting with increasing the feed rate to see what would happen. Duh, it did the same thing as last year. I just turned ti down from 3 1/2 to 3, no more smoke.

Good attachment!

Incomplete combustion comes in 2 forms - 1. Pellets spilling over the edge of the burn pot before they are reduced to ash and, 2. Smoke.

Relative to #1 - when you run the stove wide open, the burning pellets should come no closer than 1 inch from the edge of the burn pot. You should have burning pellets and about 1" of ash before the edge. If pellets are bulging and close to the edge, you might not turn them to ash before spilling over the edge, wasting energy. If the burn line is too close, dial the feed rate back a bit, may by 1/2 of a number (i.e. 3.5 to 3). The stove doesn't run wide open once everything is up to temp, so this is only for scenarios where, for instance, the room is 65 and you want it 75 degrees. When up to temp the stove will regulate itself form 5 seconds per minute of feed up to the limit you set.

Relative to #2 - smoke is also a sign of incomplete combustion, meaning that there is more fuel than air supplied by the combustion blower. This too should be evaluated when the stove is running WIDE OPEN. At night with a flashlight, you'll always see smoke... During the day, smoke is rated based on opacity or how easily you can see through it. Startup might be 50% opacity or fairly heavy smoke. If you are 10% or less (barely visible), that's reasonable and you aren't really wasting anything. If you have to struggle to see it, you're probably good. If you can easily see smoke and your flame is HUGE, try dialing back feed rate a bit to bring the air/fuel mix back into a more efficient range. Once again, dialing it back by 1/2 of a number (ie 3.5 to 3).

In most cases, you don't want to be below 3 or above 4. You'll also want to recalibrate after changing brands of pellets since the blend and size of pellet will cause it to burn/feed differently.