Instruction manual
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5.  Install oat-type LWCO, if so equipped.
  See Figures 5 and 9.
a.  Install nipples and unions in "D" Tappings.
b.  Mount hardware to low water cut-off body. 
Install assembly.
c.  Install water gage glass on low water cut-off 
assembly's tee ttings.
6.  Install Pressure Limit Control.
a.  Float LWCO only: Remove ¼" NPT plug from 
top of Low Water Cut-Off. Install Syphon and 
Limit into this tapping. See Figure 9.
b.  Probe LWCO only: Install Limit in Tapping "A" 
using ¾" NPT x 3" long nipple, ¾" NPT elbow, 
¾" NPT x ¼" NPT bushing, and syphon. See 
Figures 5 and 10. 
c.  DO NOT tighten the limit by holding the case; 
apply a wrench to the brass hex below the case.
d.  An L404F pressure limit does not require 
leveling.
7.  Connect the eld wiring to the LWCO or the 
R8239A Control Center/J-box, or burner disconnect 
J-box. 
a.  If equipped with tankless heater, connect eld 
wiring from the aquastat control to the R8239A 
Control Center transformer terminals or oil 
burner primary control's "T-T" terminals. 
  Make the wiring connections as shown in 
appropriate wiring diagram, refer to Figure 22, 
23A, 23B, 24A or 24B. 
Note: DO NOT remove "T-T" jumper unless 
wiring diagram indicates a direct connection 
from thermostat and/or tankless heater aquastat 
control to the oil burner primary control's "T-T" 
terminals. 
  Also refer to Section XI, Paragraph I, Item 2, 
"Verify Oil Primary Control" for more details.
b.  Refer to Paragraph R for details on use of 
burner disconnect junction box provided with all 
knockdown boiler builds.
P.  INSTALL TRIM AND CONTROLS WITH 
CARLIN BURNERS.
  Water boilers Only (see Figures 1A, 1B, 1C and 5).
Follow instructions in Paragraph N, Steps 1 through 7.
Steam Boilers Only (see Figures 1D and 5).
  Follow instructions in Paragraph O, Steps 1 through 6.
7.  Connect Field Wiring 
a.  Steam Boiler with Hydrolevel CG450 LWCO, 
Carlin Burner.
  Connect the eld wiring to the R8239A Control 
Center. If equipped with tankless heater, connect 
eld wiring from the aquastat control to the 
R8239A Control Center’s “R-G” terminals. 
Make the wiring connections as shown in 
Figure 22.
b.  Steam Boiler with McDonnell & Miller 
  PS-801 or McDonnell & Miller 67 LWCO, 
Carlin Burner.
  Connect the eld wiring to the LWCO or the 
burner disconnect J-box. If equipped with 
tankless heater, connect eld wiring from 
the aquastat control to the oil burner primary 
control’s “T-T” Terminals. Make the wiring 
connections as shown in appropriate wiring 
diagram, refer to Figure 23A, 23B, 24A or 24B.
Note: DO NOT remove "T-T" jumper unless 
wiring diagram indicates a direct connection 
from thermostat and/or tankless heater aquastat 
control to the oil burner primary control's "T-T" 
terminals. 
  Also refer to Section XI, Paragraph I, Item 2, 
"Verify Oil Primary Control" for more details.
SECTION III: KNOCKDOWN BOILER ASSEMBLY (continued)
Figure 9: Float-Type Low Water Cut-Off and 
Pressure Limit Installation
Figure 10: Pressure Limit Installation for Probe 
LWCO Equipped Boilers










