Page 32
The CAI is installed on the cold end header box (see figure
16). The cold end header box is a single piece made of
hard plastic. The box has an internal channel where the
combustion air inducer creates negative pressure at unit
start up. The channel contains an orifice used to regulate
flow created by the CAI. The box has pressure taps for the
CAI pressure switch hoses.
The pressure switch measures the pressure differential
across the CAI orifice (difference in the channel and cold
end header box). See table 19 for orifice size per unit.
If
replacement is necessary the gaskets used to seal
the box to the vestibule panel and the CAI to the box,
must also be replaced.
TABLE 19
SLP98DFV Unit
C.A.I. Orifice Size
-070-1 / -5
-070-6 / -9
-070-10 and later
0.780
0.833
0.775
-090-1 / -9
-090-10 and later
0.920
0.890
-110-1 / -9
-110-10 and later
1.030
1.000
TABLE 20
Pressure Switch 0' to 7500'
SLP98DFV Unit
Set Point
High Fire
Set Point
Low Fire
-070
1.00 + 0.05
0.25 + 0.05
-090
-110
*Units over 7500 ft will require a conversion kit. See table 32.
