Rev 06/2007
21
Use and Maintenance of a Catalyst
1. Do not “Hot Fire” the stove. For many years,
retailers and installers have advised
customers to build an extra hot fire to burn
the creosote deposits in the flue 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. Also, see
point #2.
2. Direct Flame contact is death to a catalyst. A
catalyst burns the byproducts in the smoke.
The gases such as CO, HC, and O2 ignite
with each other in the presence of the
catalyst, (while passing through the
honeycomb configuration). This is a
chemical reaction. Direct flame inhibits this
reaction by changing the chemical makeup
of the catalyst. The flame also breaks 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. Controlling the draft also can
reduce fly ash problems.
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.
4. Light off Temperature: CO conversion in the
Applied Ceramics catalyst begins at a very
low temperature. Usually a normal startup 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 reactants, that modifies and especially
increases the rate of a chemical reaction
without being consumed in the process.
6. Why does a catalyst stop working? Most
catalysts that are returned either are
destroyed by flame impingement, broken
due to accidents or mishandling, or have
nothing wrong with them but fly ash buildup.
A catalyst can be “saturated” with byproducts
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. 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.
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 sheet. If you find that
your catalyst should be replaced, follow the
instructions for warranty replacement that
were provided when your unit was
purchased.
Cleaning the catalyst with plain water can
reduce buildup of the catalyst – retarding
chemicals. Nothing but a soft brush, low-
pressured air or plain water should be used
to clean a catalyst. The ceramic unit is fragile
in comparison to the rest of the stove – so it
should be handled with care. A soak in warm
or hot (not boiling water) for 20 minutes is
ideal. Then allow the unit to cool at room
temperature and rinse under medium
pressure under a faucet. Allow the unit to
thoroughly dry before reinstalling it or you
will damage it. Then reinstall the unit
according to the stove maker’s or retrofit
manufacturer’s instructions. A cleaning once
every year is sufficient for most users. Clean
it when you have your flue system cleaned.
