dynamic combustion control

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Red_Fir_Smoke

New Member
Nov 7, 2021
5
N. Idaho
Good morning to all,
I'm a long time lurker, (mostly because I'm seeking solutions!)

I have the dubious pleasure of owning a Breckwell Big E, and for the constant effort of owning said machine, I might as well just have a wood stove!
It is ran off a tstat on hi/lo with the additional feed setting on 2-4, usually at #3 feed rate sometimes #4
I live just a few miles from the Rocky Canyon Pellet Co, and as they will sell wholesale early in summer, I stock up on their "Ultra Premium Red Fir" pellets.
It has required constant input to keep operational, If conditions are right and the moon is in the seventh house, I might feed a couple of bags through and then the fire is out (often due to bridging, but frequently due to oversupply of air during low idle operation).
The bridging/ accumulated fines problem currently seems insurmountable as I don't intend to switch brands and Rocky Canyon exerts no control over pellet length but seems to let them break at random.
But the over ventilated fire seems like it should be easily cured... at first I thought to control airflow via throttling the inflow using an Arduino prompted by a millivolt signal from an exhaust sensor, or a lux meter, but the exhaust sensor is too easily fouled with soot (that's why auto sensors are placed in the exhaust stream in the catalytic convertor or very close to the exhaust manifold where the fouling will burn off!) and the lux meter is simply too imprecise.
But while listening to the operation of the beast it occurred to me the room blower (or the signal thereto!) could be used to begin a timer (30-90 seconds?) for the existing feed rates, fuel to flash off, and then throttle back on the combustion blower (suction) by a percentage....
Obviously it needs to keep rolling fast enough to keep the vacuum sensor engaged, but the combustion blower is designed to pull in the vacuum sensor at wide open airflow and my airflow is 3/4 - 7/8 restricted during normal operation… in theory I could slow down the combustion blower (there by reducing overall airflow) and still keep the equivalent vacuum that the stove would have had at wide open throttle....
Whadaya think?
 

Mt Bob

Minister of Fire
Oct 31, 2013
3,632
park county montana
Don figured out a fix for this,many years ago. Will leave you a link to read.

 

Red_Fir_Smoke

New Member
Nov 7, 2021
5
N. Idaho
Don figured out a fix for this,many years ago. Will leave you a link to read.

Well....
I don't think it's a matter of the vacuum switch dropping out, (i jumpered it for a few tests) it seems more that there is more air (and therefore a faster burn rate) of a very few pellets, than the very few pellets can sustain. In watching it till it dies, the fire dies down, and a few pellets trickle in, and it flares up for twenty plus cycles, but each time there is just fewer coals available to light the fresh charge.
If I set the airflow to a sooty burn on 3 then the coals survive (and the flame looks nicer on low) but eventually the soot blackens the glass, ... but the flame persists.

Also it seems that the cool down period is remarkable! After a charge is delivered to a dead coal bed it will continue to run (and dump new charges) usually till half of the burn chamber is filled (overflowing if a heat call from the tstat occurs !) before it shuts off.
 
Last edited:

Mt Bob

Minister of Fire
Oct 31, 2013
3,632
park county montana
Have you tried your heat level 1 at it's highest feed rate,1-4, like he says? You can always call him,also.
 

Ssyko

Minister of Fire
Nov 6, 2017
4,293
Lorraine NY
Hi-low has been an issue since the beginning of breckwell line. Some have changed out the control board with a kozi to utilize the variable combustion blower speeds and have been quite successful. Off and on may use the ignition more but it works well
 
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Dataman

Minister of Fire
Sep 10, 2018
1,036
Newport, Wa
Makes me glad I got Harmon. Turn it on and it runs and eats pellets. Even decomposed ones.

IMG_20210119_064818105.jpg
 

Red_Fir_Smoke

New Member
Nov 7, 2021
5
N. Idaho
Excellent!
I did a search for "Kozi control in a Breckwell" and that seems to be just what I seek,
Thank you!
(and thanks for all the other advice too!)