Pellet Boiler Maintenance Tips

Empty Your Ash Containers Once a Week

Of all the problem calls that we get, ash build-up is the #1 cause. Dump your boiler’s ash containers once a week! Do it on the same day each week. (Ash Wednesday?) If it is full to the top, check for ash build-up in the chamber behind the ash box(es).

The above refers mainly to commercial applications where dozens of tons of wood pellets are burned each year.

In residential boilers, you should check your ash container weekly so you get a sense of how frequently your boiler’s ash will need to be dumped.  In very cold weather we say, check the ash box weekly!  But in warmer weather the container could go for 3-4 weeks before it must be emptied.

Fines Management

Concentrated pellet dust can be a killer to good boiler performance. Every load of bulk delivered pellets has a small percentage of fines. When they are mixed in evenly with pellets on their way into a boiler, everything is FINE. But when fines get concentrated–which most often happens inside the storage silo–a variety of control faults can occur that shut down your boiler. So if you see an excessive amount of fines in your boiler’s day bin, trouble may be looming.

Fines concentration mainly occurs in silos with 45-degree or lower slopes due to funnel flow. Silos with bottom slopes of 60-degrees tend to accumulate far fewer fines because pellets go down in a Mass Flow.

The cures for fines build-up? One is to vacuum fines out of your low slope silo when it becomes “empty”. Do this once a year or so which will prevent heavier concentrations that occur after years of fillings. Vacuuming out a bag silo every year or two is also a good practice, even with a MESys type “Spring-Bag” (see below). If you have a Froling funnel bag, a vibrator can be added to these that runs when the feed blower turns on, getting fines to exit with the pellets before they become concentrated. Another solution is to install a fines cyclone in the pneumatic feed line.

Planning a pellet boiler installation for your home or building? Choose an interior silo like the MESys FleXILO “spring-bag” that looks like a cube when full but the springs pull up the floor into a steep V when it nears empty. Or get a Froling silo with a vibrator. If you are planning on an exterior silo, the 60-degree bottom cone is recommended with pneumatically filled boilers.

If you are planning a new installation, specify an exterior silo with 60-degree bottom cone or build an interior silo with 60-degree walls and a central auger. Yes, this reduces the interior volume of the silo but if the pellets are stuck in place on a 45-degree slope, they are of no use to you unless you manually rake them down.

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