Combustion Air Filter
This heater is supplied with an integral combustion air
filter. This filter will reduce the amount of particulates
passed through the combustion system and heat
exchanger but will not protect against chemical inside
air contamination (See Appendix). The filter must be
checked periodically to verify that adequate combus-
tion air is being supplied to the heater. See the
Maintenance section of this manual for information on
checking the filter and establishing service intervals.
Direct Vent
If outside air is drawn through the intake pipe directly
to the unit for combustion:
1. Convert the unit to draw air through an air intake
duct at the rear of the cabinet. As shipped,
XTherm heaters draw combustion air from inside
the cabinet.
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6. Optional—For applications where condensation
mayform on cold intake air ducting, install the con-
densate drip pan to the bottom of the air filter box
usingthe four screws provided (make sure the pan
is angled slightly downward toward the rear of the
heater as shown in Fig. 9).
7. Remove the air intake cover panel by removing
the 5 phillips head screws holding it in place.
2. Turn off all power to the heater.
3. Ensure that the heater is cool to the touch before
proceeding with the installation.
4. Remove both the left and right rear side access
panels.
5. From the right-rear side access area, install the
inside air intake cover panel using the nine hex-
head screws provided (see Fig. 8).
InsideAir Intake
Opening
Fig. 7: Remove the Rear-sideAccess Panels
InsideAir Intake
Cover Panel
Fig. 8: Install the InsideAir Intake Cover Panel

Condensate

Drip Pan

Fig. 9: Install the Condensate Drip Pan
AirIntake
CoverPanel
AirFilter
Access
Panel
Fig. 10: Remove theAir Intake Cover