AHRI APEX, Installation, Operating And Service Instructions

Page: 13 / 124

13
III. Pre-Installation and Boiler Mounting
G. General (continued)
H. Boiler Stacking
1. For installations with unusually high space heating
and/or domestic hot water heating loads, where
employing 2 Apex boilers will offer the benefits
of greater operational efficiency, floor space
savings and boiler redundancy, Apex boilers may
be installed stacked maximum one boiler on top
of another. Refer to Table 3 “Apex Boiler Model
Stacking Combinations” for details.
Table 3: Apex Boiler Model Stacking
Combinations
Bottom Boiler
Model
Top Boiler Model
APX425
APX425
APX525 APX425 or APX525
APX625 APX425, APX525 or APX625
APX725 APX425, APX525, APX625 or APX725
APX825
APX425, APX525, APX625, APX725 or APX825
2. To field assemble individual Apex boilers into a
stackable configuration, use the steps below:
a. Position the bottom boiler first. Refer to Sections
II “Unpacking Boiler” and III “Pre-Installation
& Boiler Mounting” of the manual for details.
Always position higher input boiler model as
bottom boiler.
b. Each Apex boiler is factory packaged with
2 stacking boiler attachment brackets (P/N
101679-01) and the bracket mounting hardware
[six (6) self-drilling hex washer head plated #8
x ½” long screws, P/N 80860743]. Locate and
remove the brackets and the hardware. The
stacking boiler attachment bracket has three
7/32” diameter holes punched in a triangular
pattern. See Figure 3 “Stacking Boiler
Attachment Bracket Placement”.
c. Apex boiler left and right side panels have a
series of dimples at panel top and bottom. These
dimples are positioning dimples for stacking
boiler attachment bracket mounting screws. Side
panel bottom positioning dimples are evenly
spaced from boiler front and back, while side
panel top positioning dimples follow specific
pattern to compensate for Apex boiler model
variable depth.
d. Position the upper boiler on top of the bottom
boiler and align boiler front doors and sides flush
with each other.
• Place first stacking boiler attachment bracket
onto the upper boiler left side panel, at the
panel lower left corner and align bracket two
upper holes with corresponding side panel
lower dimples.
• The remaining lower bracket hole must align
with a matching bottom boiler left side panel
top positioning dimple.
• Once bracket holes and side panel dimple
alignment is verified, attach the bracket to
top and bottom boiler left side panels with
the mounting screws.
e. Repeat above procedure to install second
stacking boiler attachment bracket and secure the
stacked boiler right side panels together at the
front right corner.
f. Install the third stacking boiler attachment
bracket to secure top and bottom boiler left side
panels at the rear left corner. Align the bracket
holes with corresponding positioning dimples in
the top boiler and bottom boiler left side panels,
then secure bracket with the screws.
g. Repeat above procedure to install the fourth
stacking boiler attachment bracket to secure
stacked boiler right side panels at the rear right
corner.
3. When installing stackable boiler combinations
observe the following guidelines:
a. Venting - Top and bottom boilers must have their
individual vent piping and vent terminals.
WARNING
Asphyxiation Hazard. No common manifold
venting is permitted. Each boiler must have its
own individual vent and combustion air pipes
and terminals.
For sidewall venting individual model vent
terminals must terminate no closer than 12
in. (300 mm) horizontally and 3 ft. (900 mm)
vertically from each other in order to prevent
combustion air contamination. For vertical
through the roof venting, individual vertical
vent terminals, if level with each other, must
be spaced no closer than 12 in. (300 mm)
horizontally. If vertical terminals cannot end in
one plane, they must be spaced no closer than 3
ft. (900 mm) horizontally.
Follow instructions in Section IV “Venting”
of the manual for specifics of individual boiler
vent termination. Follow instructions in Section
V “Condensate Disposal” for each individual
boiler flue gas condensate line construction and
condensate disposal. Terminating individual
boiler condensate lines into common pipe prior
to drain disposal is permissible, providing
common pipe has sufficient flow capacity
to handle combined condensate volume of
stackable combination.