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29
Vermont Castings Defiant
The Catalytic Element
This wood heater contains a catalytic combustor,
which needs periodic inspection and replacement for
proper operation. In the United States it is against the
law to operate this wood heater in a manner inconsis-
tent with the operating instructions in this manual, or if
the catalytic element is deactivated or removed.
Under normal operating conditions, the catalytic
combustor should remain active for two to six years
(depending on the amount of wood burned). However,
it is important to monitor the combustor periodically to
ensure that it is functioning properly, as well as to
determine when it needs to be replaced. A non-
functioning combustor will result in a loss of heating
efficiency, and an increase in creosote and emissions.
Inspection and Cleaning
Inspect the combustor “in place” for fly ash accu-
mulation and physical damage three times per year.
Clean the combustor as needed. Do not remove the
combustor unless a more detailed inspection is war-
ranted because of diminished performance as outlined
in the next section.
The refractory package that houses the catalytic
combustor should be inspected annually for a buildup
of fly ash and cleaned if necessary. This may be done
when you examine the combustor.
When To Suspect a Combustor Problem
The best way to evaluate the performance of your
Defiant’s combustor is to observe the amount of smoke
leaving the chimney — both when the combustor has
“lighted-off” and when it has not. Follow these steps:
• With a fire going and the combustor properly
activated, with the damper closed to route smoke
through it as described in the Operation Section, go
outside and observe the smoke leaving the chim-
ney.
• Then, open the stove damper and once again check
the smoke leaving the chimney.
You should see significantly more smoke when the
stove damper is open and exhaust does not pass
through the combustor. However, be careful not to
confuse smoke with steam from wet wood. Steam
dissipates in the air quickly; smoke does not.
If this test indicates a problem, consider other
possible factors as well, such as the weather or a
change in the quality of your fuel. In warm weather,
draft is weaker than it is in colder winter weather, and
fires can burn sluggishly. Small, hot fires are a good
solution under these conditions.
Burning “green” (insufficiently seasoned) wood will
result in poorer performance than burning properly
seasoned fuel. You may have to run your stove hotter
(more air) to achieve acceptable performance using
green or wet wood.
Also, consider any changes in your operating
routine.
Once you have ruled out any other possible causes
for a decline in performance, inspect and clean the
combustor if necessary. Be sure to protect any surface
you use for setting the stove parts aside.
Inspecting the Combustor
1. Lift the baffle off its support brackets, and then
remove it from the stove and place it on a protected
surface. (Fig. 36)
2. Use a flashlight, and a mirror if necessary, to exam-
ine the combustor. If no fly ash or damage is visible,
the inspection is complete and you may replace the
baffle. If closer examination or cleaning is needed,
go to the next section.
Baffle Support
Brackets
Catalytic
Element
ST555
Fig. 36 Lift the baffle off its supports to inspect the catlyst.
Removing and Cleaning the Combustor
1. Remove the firebricks. Lift off the steel clip and
remove the bricks individually. (Fig. 37)
2. Tap the left and right wedges upward, and remove
the lower fireback by pulling it forward. You can
either let it lie face down on the firebox floor, or
remove it from the stove, through the front door
opening. (Fig. 38)