MPO-IQ Installation, Operating, and Service Instructions

16
• 1-1/2" NPT horizontal left or right side return
piping - Install relief valve vertically in 3/4" NPT
tapping on tee. See Figure 5.
Step c. Pipe discharge of relief valve as shown in Figures
13A and 13B. Installation of the relief valve must
be consistent with ANSI/ASME Boiler and Pressure
Vessel Code, Section IV.
WARNING
Safety valve discharge piping must be piped near
oor to eliminate potential of severe burns. Do not
pipe in any area where freezing could occur. Do not
install any shut-off valves, plugs or caps.
2. Install drain valve, see Figure 6.
Step a. Apply pipe sealant to both ends of 1-1/4" NPT
x 5" lg. nipple. Thread nipple into 1-1/4" NPT lower
rear tapping on rear section.
Step b. Thread 1-1/4" x 1-1/4" x 3/4" NPT tee on opposite
end of 5" lg. nipple installed in Step a.
NOTE: Based on access for servicing and location
of sewer or oor drain, when tightening these ttings,
determine if drain valve is to be located on the left or
right side.
Tighten nipple and tee into 1-1/4" NPT lower rear
tapping on rear section until joints are water tight for
desired position.
Step c. Apply sealant to 3/4" NPT thread on drain valve.
Thread into 3/4" NPT tapping on side outlet of tee. Use
hex nut portion to tighten valve until water tight.
3. Connecting eld wiring, refer to Figures 7, 28A thru
28C.
Step a. Locate the black, white and green harness wires
labeled "120V Power Supply" inside internal junction
box, see Figure 7. Using wire nuts, connect the 120
volt power supply eld wires to the harness wires.
Step b. Locate the yellow and white wires labeled "System
Circulator" inside internal junction box, see Figure 7.
Using wire nuts, connect the 120 volt eld wires to
the harness wires.
Step c. If applicable, locate the violet and white wires
labeled "DHW Circulator" inside internal junction
box, see Figure 7. Using wire nuts, connect the 120
volt eld wires to the harness wires.
Step d. If applicable, locate the brown wire labeled "DHW
Demand" inside internal junction box, see Figure 7.
Using wire nut, connect the 120 volt eld wire to the
harness wire.
Step e. 24V thermostat eld wiring will enter through
5/16" snap bushing located on either the right side or
left side jacket panel. Connect the 24V wiring from
the thermostat to the "T-T" terminals on the Option
Control Panel.
Step f. To connect other external devices, refer to the
instructions included with these devices.
II. PACKAGED BOILER ASSEMBLY - TRIM & CONTROLS (cont'd)
Figure 6: Piping Arrangement for Drain Valve and Indirect Water Heating Return