Hearthstone Quality Home Heating Products, Inc.
Heritage Model 8090 Pellet Stove
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overfeed the stove, causing high temperatures or smothering the fire. Most appliances now have
simple adjustment mechanisms to overcome these difficulties. Proper adjustment of fuel to air
settings for the particular fuel must be made for maximum performance as the appliance owner
changes the fuel source to one with different density.
Bridging and blockage or auger jamming caused by unsuitable pellet diameter or length, or by
excessive fines, indirectly affects combustion by depriving the combustion chamber of fuel.
3.1.2 HEAT TRANSFER
Fly ash gradually builds up on heat exchanger tubes or fins. The coating of ash acts as an insulator
and prevents proper transfer of heat to the convection air passing through the tubes into the home.
The frequency of cleaning heat exchangers is determined in large part by the ash content of the
fuel.
3.1.3 MECHANICS
High ash and fines content can build up on impellers and affect blower motor durability.
Jamming from excessive fines or improper pellet size can affect auger durability.
3.2 MAINTENANCE
Using a fuel that is not suited for a particular appliance increases the frequency of maintenance.
Clinkers from high silica content fuel (or from lowered ash fusion temperatures brought about by the
presence of alkaline salts) must be removed before they block combustion air, affect performance, or
cause other maintenance needs. High ash and/or fines in fuel necessitate more frequent cleaning of the
burn pot/grate, ash storage areas, heat exchangers and venting system. The systems and components
of pellet appliances are interdependent and sensitive to proper maintenance. Simple maintenance
tasks, left unattended, can become a need for total system maintenance as well as a source of owner
frustration. The frequency of component replacement is also increased by the lack of regular, properly
performed maintenance.
4. SUMMARY
Residential pellet fuel is recovered biomass products processed to be of uniform size, density, moisture
content, and ash content.
Feed stock is separated from unwanted contaminants, pulverized into small pieces, dried, compressed,
cooled, and bagged in the pellet manufacturing process.
PFI standards for density, dimensions, fines, sodium and ash are voluntarily complied with by pellet
manufacturers. Recommended labeling includes an analysis of these factors.
Ash content, the primary maintenance factor, is the only difference in composition between standard (up to
3%) and premium (less than 1%) grades of fuel in PFI standards.
The fuel quality standards include characteristics that affect performance, maintenance, durability, and
customer satisfaction. Another factor not included in the standards is silica content, the primary cause of
clinkering.
