User Guide

®
CONDENSING GAS BOILER — 70/110/155 Advanced Manual
Part number 550-100-193/0817
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Placing multiple boilers
1. Locate multiple boilers with spacings shown in Figure 3.
Provide the indicated clearances around boilers for access
and servicing.
If recommended dimensions are not possible,
provide at least the minimum clearances given
in the Evergreen
®
boiler manual. Also follow
local codes.
2. If boilers are floor-mounted, construct a boiler foundation
if boiler room floor is uneven or if there is a danger of
flooding. Size the foundation to allow for clearance and
spacing dimensions shown in Figure 3.
3. Provide a minimum 30-inch walkway in front of the boil-
ers to ensure accessibility.
4. Uncrate, assemble and mount boilers according to instruc-
tions in the Evergreen
®
boiler manual.
5. Provide clearances needed for installation of venting, air
piping, gas piping, expansion tank, primary circulator
and other accessories. Clearances must comply with all
applicable codes.
Manifolded combustion air option
1. Multiple Evergreen
®
boilers can use a common combus-
tion air manifold.
a. Provide minimum clearance to adjacent vents and
grade/snow line as shown in Figure 4.
b. Provide minimum free area in duct (adjusted for
louver restriction) of
1 square inch per 2,000 Btuh
total boiler input. See below. Also see information in
Boiler Ratings section of boiler manual.
c. If combustion air damper is used, wire to boilers to
prevent operation, except after damper has opened.
ONLY air piping can be combined. DO NOT
use combined vent piping. Flue gas leakage and
boiler component damage can occur. Failure to
comply could result in severe personal injury,
death or substantial property damage.
2. Calculate required cross sectional area of combined com-
bustion air duct (for area in square inches):
MINIMUM DUCT AREA
= TOTAL MBH INPUT DIVIDED BY 2
3. Example: A multiple boiler system with six (6) EVG 155
boilers has a total input of 6 x 155 =
930 MBH (930,000
Btuh). The required duct cross sectional area would be:
MINIMUM DUCT AREA
= 930 DIVIDED BY 2
= 465 sq. inches
Figure 3 Side-to-side mounting of multiple Evergreen
®
boilers
Figure 4 Manifolded combustion air option
Multiple boiler installations