Install Instructions

20
4. Pick-up the LWCO harness Molex end and feed it
into the enclosure, thru external electrical enclosure
top ange front left 7/8” hole; then, snap-in harness
BX connector into the hole, and, plug-in Molex
connector into dedicated LWCO receptacle inside
the enclosure (middle left off transformer/relay). See
“ Control Plug-In Diagram” label attached to inside
of the enclosure cover for details.
N. PRESSURE GAUGE AND GAUGE GLASS
INSTALLATION.
1. Remove the 6” water gauge glass set from Part
Carton.
2. Install the gauge glass using the two ½” NPT
tappings to the right of the probe LWCO. See Figure
7 “Purpose of Tappings & Bosses”.
3. Thread the pressure gauge into 1/4” NPT tapping of
the front section. See Figure 7 “Purpose of Tappings
& Bosses”. Tighten with wrench applied to the
square shank of the gauge.
CAUTION
Do not apply pressure to gauge case, as this may
result in inaccurate readings.
O. FLOAT LWCO (MCDONNELL-MILLER #67),
AND GAUGE GLASS INSTALLATION.
1. Pre-assemble oat-type LWCO per Figure 9 "Float-
Type LWCO and Gauge Glass Installation".
2. Install two ½” NPT x 2½" long Sch 40 brass nipples,
supplied loose inside Control Carton (disregard two
½" NPT x 1½" long brass nipples provided with
#67 LWCO package) and ½" NPT brass unions into
upper and lower front section tappings. See Table 3
"Purpose of Tappings & Bosses" and Figure 7.
3. Install water gauge glass on low water cut-off
assembly tee ttings.
4. Do not remove ¼” NPT plug factory installed on top
of #67 LWCO.
5. Insure that 3/8" NPT plug (provided within #67
LWCO package) is installed at bottom of #67
LWCO.
6. Remove #67 LWCO J-box cover.
7. Screw LWCO to External Wiring Enclosure wiring
harness (end with fork and female disconnect
terminals) connector into low water cut-off J-box
top tting, and attach wires to the terminals per
LWCO wiring detail shown in Figure 9 "Float-Type
LWCO and Gauge Glass Installation".
8. Re-install #67 LWCO J-box cover.
9. Pick-up the LWCO harness Molex end and feed it
into the enclosure, thru external electrical enclosure
top ange front left 7/8” hole; then, snap-in harness
BX connector into the hole, and, plug-in Molex
connector into dedicated LWCO receptacle inside
the enclosure (middle left off transformer/relay). See
“ Control Plug-In Diagram” label attached to inside
of the enclosure cover for details.
10. Pick-up the pressure limit harness Molex end
and feed it into the enclosure, thru External
Electrical Enclosure top ange rear left 7/8” hole;
then, snap-in harness BX connector into the hole,
and, plug-in Molex connector into dedicated pressure
limit receptacle inside the enclosure (upper left off
transformer/relay). See “ Control Plug-In Diagram”
label attached to inside of the enclosure cover for
details.
P. AQUASTAT CONTROLLER INSTALLATION
(BOILERS WITH TANKLESS HEATER ONLY).
1. On boilers with tankless heater, install the L4006A
aquastat controller well (found in Part Carton) into
½” NPT tapping in tankless heater plate.
2. Remove the L4006A aquastat controller with factory
attached harness from Control Carton.
3. Slip the bulb of the aquastat controller into the well
and secure the controller in place with the set screw.
WARNING
Aquastat bulb must be fully inserted into the
well.
4. Feed the L4006A aquastat controller harness end
thru external electrical enclosure top ange middle
right bushed hole. See “ Control Plug-In Diagram”
label attached to inside of the enclosure cover for
details.
5. See Figures 19, 20 and 21 (whichever applicable)
for tankless heater aquastat connection details.
6. Using needle nose pliers form hook on harness each
stripped end and wrap hooks around screws under
terminals "R" and "G" of the R8285C Transformer-
Relay; then, tighten screws securely.
Q. SAFETY VALVE AND DRAIN VALVE
INSTALLATION.
1. Remove safety valve and related piping (3/4”
NPT x 3” lg. black nipple, 3/4” NPT x 8” lg. black
nipple, ¾” NPT 90° black elbow and ¾” NPT black
coupling) from Part Carton.
2. Thread 3/4" NPT x 3” lg. black nipple into rear
section safety valve tapping, install ¾” NPT 90°
black elbow facing upward, then, thread 3/4" NPT
x 8” lg. black nipple into the elbow, and, install ¾”
NPT black coupling onto nipple end.
SECTION II: UNIT-PAK BOILER ASSEMBLY (continued)