LAARS Mighty Max VW (Sizes 320M - 400M) - Installation, Operation and Maintenance Instructions - Manual (Page 14)

Page 14
LAARS Heating Systems
and do not permit any other condition, such as an
exhaust blower, to affect the air supply for combustion
and ventilation.
2.11.2 Ducted Combustion Air
Combustion air can be brought directly to the
heater through a duct of suitable size and length (see
Table 7). Consult Laars about installations not covered
by Table 7.
Combustion air must be taken from out-of-doors
by means of the Laars side wall terminal.
Locate the terminal within 10 feet (3m) of the
heater vent exhaust terminal, but no closer than 3 feet
(0.9m) (centerline distance).
Do not locate the air inlet terminal near a source
of corrosive chemical fumes (e.g., cleaning fluid,
chlorine compounds, etc.). Locate it so that it will not
be subject to damage by accident or vandalism. It must
be at least 7 feet (2.1m) above a public walkway.
Use single-wall galvanized pipe for the
combustion air duct. Route the duct to the heater as
directly as possible. Seal all joints with tape. Provide
adequate hangers. The heater must not support the
weight of the combustion air duct.
When combustion air is ducted to the heater,
other provisions must be made for heater room
ventilation. VW heaters lose less than 1 percent of
their input rating to the room, but other heat sources
may be present. Provide enough ventilation air to meet
comfort specifications. Make sure the ventilation air is
not directed at the heater, water piping or other
equipment which could be damaged by freezing.
2.11.3 Conversion for Ducted
Combustion Air
The conversion to ducted combustion air
requires the parts listed in Table 8. Follow these
procedures to convert the heater (see Figure 10):
Boiler Size Assembly Number
320 20258101
400 20258102
Table 8. Combustion Air Assembly.
1. Remove the louvered plate from the left side of
the heater.
2. Remove the adapter plate from the shipping
container.
3. Install the blower motor housing collar in gasket.
4. Slip one end of the inlet pipe over the collar on
the adapter plate.
5. Slide the inlet pipe and adapter plate into the
heater opening until the pipe is aligned with the
blower motor.
Figure 10. Ducted Combustion Air Conversion.
Ducted Combustion
Air Pipe
Inlet
Pipe
Adapter
Plate
Louvered
Plate
6. Slip the end of the inlet pipe over the blower
motor housing collar.
7. Secure the adapter plate to the side of the heater
with the 4 screws.
2.11.4 Combustion Air Piping
Run piping of the appropriate size between the
air intake terminal and the heater (see Table 7). Table
9 lists the materials for piping the heater.
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