AHRI APEX, Installation, Operating And Service Instructions

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n. Apply pipe dope to the switch-threaded brass-
bushing end. Then, mount the switch threaded
end with the attached paddle into 1-1/2 in. x
1-1/2 in. x 1 in. NPT tee branch and tighten
such that distance between bottom of switch
housing and top of tee branch is approximately
1-11/16 in. (43 mm). Insure the switch paddle
is positioned perpendicular to the flow direction
for the best flow sensitivity. Do not tighten the
switch by grasping the switch enclosure. Use the
wrenching flats on the bushing only. The turning
radius required for the switch mounting is 3 in.
(80 mm).
o. For flow switch wiring refer to Section VIII
“Electrical” of these instructions.
2. Models APX625 and APX725 (see Figure
19B, “Factory Supplied Piping and Trim
Installation – APX625 and APX725”)
a. Locate 2 in. x 2 in. x 3/4 in. NPT black tee, 3/4
in. NPT x close black nipple, and 3/4 in. NPT
black tee. Install close nipple in branch of 2 in.
x 2 in. x 3/4 in. NPT tee. Install branch of 3/4 in.
NPT tee onto other end of close nipple. Install
2 in. x 2 in. x 3/4 in. NPT tee onto 2 in. MPT
supply connection at front of boiler, making
sure branch of 2 in. x 2 in. x 3/4 in. NPT tee is
oriented towards front of boiler and run of 3/4”
NPT tee is oriented vertically.
VI. Water Piping and Trim
A. Factory Supplied Piping and Trim (continued)
Figure 19B: Factory Supplied Piping and Trim Installation - APX625 and APX725
e. Install drain valve into tee bottom outlet.
f. Locate and remove (2) 1½ in. NPT x 2 in. long
black nipples, 1½ in. x 1½ in. x ¾ in. NPT
black tee, 1½ in. x 1½ in. x 1 in. NPT black tee,
packaged flow switch with paddles, ¾ in. x ¼ in.
NPT black reducing bushing and temperature &
pressure gauge.
g. Mount (1) 1½ in. NPT 2 in. long nipple into
1½ in. FPT boiler supply tapping (see Figures
1A and 1B). Then, install 1½ in. x 1½ in. x ¾
in. NPT tee onto the nipple, making sure ¾ in.
branch outlet is in horizontal plane and facing
the boiler front.
h. Install ¾ in. x ¼ in. NPT black reducing bushing
into the tee branch. Then, put in temperature &
pressure gauge.
i. Install second 1½ in. NPT x 2 in. long nipple into
1½ in. x 1½ in. x ¾ in. NPT tee run.
j. Mount 1½ in. x 1½ in. x 1 in. NPT black tee onto
the nipple, making sure tee 1 in. NPT branch
outlet is in upright position.
k. Remove flow switch and paddles from packaging
carton. Also see/follow Taco Instruction Sheet
for Flow Switch Kit (supplied with the flow
switch) for specific details.
l. Select the paddle stamped “1” for the APX425
and APX525.
m. Attach paddle to flow switch stem using supplied
machine screw.