MPO-IQ Installation, Operating, and Service Instructions

Figure 5: Return Injector Piping and Relief Valve

Assembly Details

II. PACKAGED BOILER ASSEMBLY - TRIM & CONTROLS (cont'd)

Figure 4D: Burner Swing Door Insulation

1. Install return injector piping and relief valve, refer to

Figure 5.

Step a. Locate the return pipe ttings and injector. Apply

sealant to the 2” NPT injector threads. Insert injector

into 2” NPT upper rear tapping on rear section. Thread

2” NPT x 1-1/2” Reducing Elbow onto 2” NPT injector.

Apply thread sealant to the 1-1/2” NPT nipple. Thread

1-1/2” NPT nipple into 1-1/2” NPT end of reducing

elbow. Thread 1-1/2” NPT x 1-1/2” NPT x 3/4” NPT

Tee onto 1-1/2” NPT nipple. Tighten pipe ttings until

relief valve orientation is correct for your installation

and joints are watertight.

Note: Based on system return piping and access to service

boiler, see Figures 1, 13A and 13B, predetermine if

injector piping orientation is to be positioned for

vertical, horizontal left or horizontal right side return

piping as shown in Figure 5.

Step b. Install relief valve using 3/4" NPT tapping on tee.

Relief valve must be installed in vertical position. If

orientation of return injector piping is for:

• 1-1/2" NPT vertical return piping - Install

3/4" NPT x 90° street ell (not furnished)

into 3/4” NPT tapping on tee. Install relief

valve vertically into street ell. See Figure 5.