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SECTION VI
PREVENTIVE MAINTENANCE / PARTS REPLACEMENT
THE CATALYSTS
The catalysts in your stove are designed for many years of use. If after several years of use, the efficiency of the
stove decreases or if a notable amount of smoke is observed, the catalysts may need to be replaced. See the
Catalyst Warranty prior to replacement. The following points are some general guidelines from the catalyst
manufacturer.
1. Do not “hot fire” the stove. For many years retailers and installers have advised customers to build an extra
hot fire to burn creosote deposits in the fire system. This advice may be acceptable for non-cat stoves, but
can be death to a catalyst. Why? Because the catalyst is reducing the particulate, or creosote buildup,
therefore the need to “hot fire” is eliminated. Proper chimney cleaning procedure should be followed.
2. Direct Flame contact is death to a catalyst. A catalyst burns the by-products in the smoke. The gases such as
CO, HC, and O
2
ignite with each other in a chemical reaction in the presence of the catalyst (while passing
through the honeycomb configuration). Direct flame inhibits this reaction by changing the chemical make-up
of the catalyst breaking down the substrate or ceramic. This problem is called flame impingement. Today’s
modern stoves are designed so that flame impingement is unlikely. However, a strong, fast draft can pull the
flame into the catalyst. Or, a hot fire, with all the air controls and/or the ash door open can literally torch the
catalyst. The remedy for the hot fire related flame is to advise customers not to “hot fire” the stove. The
customer will enjoy their catalysts longer and with better performance if these guidelines are followed. Fly
ash problems also can be reduced by controlling the draft.
3. The “Glow” Misconception: A catalyst can glow during certain stages of combustion. The determination
that a catalyst is not working simply because it does not glow is inaccurate. During the low burn cycle, when
the catalyst is doing the bulk of its work, it usually does not glow. Also, extremely dry wood (oak, ash, etc.)
can burn clean enough not to produce a glow in the converter. In most new stoves, you cannot see the
catalyst.
4. Light Off Temperature: CO conversation in the Applied Ceramics catalyst begins at a very low
temperature. Usually, a normal start up to produce a coal bed will produce more than sufficient temperatures
to begin catalytic combustion.
5. The catalyst is not consumed or “used up”. The nature of a catalytic reaction is defined as follows, by the
American Heritage Dictionary, Second College Edition: cat.a.lyst n “1. Chem. A substance, usually present
in small amounts relative to the reactants, that modifies and especially increases the rate of a chemical
reaction without being consumed in the process.” This means your catalyst is always there. This also means
that gases that would normally go out the flue system and pollute the environment are being burned to create
more heat from less wood.
6. Why does a catalyst stop working? Most catalyst that are returned are either destroyed by flame
impingement, broken due to accidents or mishandling, or have nothing wrong with them but fly ash build-up.
A catalyst can be “saturated” with by-products of wood burning such as potassium. This is chemical
saturation. The prohibitive chemical will fill in the chemical “holes” that the gases normally use for reaction.
This process of saturation can be slowed by regular maintenance of the catalyst. Saturation can take several
years since there are units in use for over five years. Burning garbage, painted woods, or large amounts of
colored paper can poison your unit. Poisoning, however, is very difficult to do. Burning colored paper
causes more of a fly ash problem than a risk of poisoning. NEVER BURN RUBBER OR PLASTIC.
7. Burn only seasoned dried wood. Wood should be dried for at least 12 months prior to burning. The wood
should be FREE of any moisture such as RAIN or SNOW. Wet wood creates water vapor which can drop the
temperature of the catalyst. The results can be plugging, clogging, and thermal shock to the catalyst. When a
catalyst has ceased to be effective, you will notice increased fuel usage and your chimney sweep will notice
increased creosote in your system. Before you replace the unit, review this section. If you find that your
catalyst should be replaced, follow the instructions for warranty replacement that were provided when your
unit was purchased.