AERCO Esteem O&M Manual - Manual (Page 24)

18
Expansion Tank and Makeup Water
Graph 2 and Graph 3 on page 91 For other
piping arrangements, consult the Engineering
Department at AERCO International.
On piping applications using a single zone or
other recognized piping design arrangements,
it is recommended that the installer uses flow/
check valves with weighted seats at or near
the appliance to prevent gravity circulation.
Expansion Tank and Makeup Water
Ensure the expansion tank is properly sized
for the boiler volume 7 gallons [26 L] for
Esteem 399 Low NOx and the system volume
and temperature.
C
AUTION
Undersized expansion tanks will cause
system water to be lost through the
pressure relief valve and cause addi-
tional makeup water to be added to the
system. Eventual boiler heat exchanger
failure can result due to this excessive
makeup water addition.
The expansion tank must be located as shown
in Figure 7 and Figure 8 on page 21 when using
a primary/secondary piping arrangement or as
per recognized design methods. Refer to the
expansion tank manufacturer instructions for
additional installation details.
Connect the expansion tank to an air separa-
tor only if the air separator is located on the
suction side (inlet) of the system circulator.
Always locate and install the system fill con-
nection at the same location as the expansion
tank connection to the system.
D
IAPHRAGM
E
XPANSION
T
ANK
Always install an automatic air vent on the top
of the air separator to remove residual air from
the system.
C
LOSED
-T
YPE
E
XPANSION
T
ANK
It is recommended to pitch any horizontal pip-
ing upwards toward the expansion tank 1 inch
per 5 feet of piping. Use 3/4” piping for the
expansion tank to allow air within the system
to rise.
C
AUTION
DO NOT install automatic air vents on
a closed-type expansion tank system.
Air must remain in the system and be
returned to the expansion tank to pro-
vide an air cushion. An automatic air
vent would cause air to be vented from
the system resulting in a water-logged
expansion tank.
Circulator
The Esteem 399 Low NOx must be supplied
with a Central Heating (CH) circulator. The
circulator when wired directly to the Esteem
399 Low NOx will allow for domestic hot water
priority and to provide circulation for the freeze
protection feature of the boiler control. See
Graph 2 and Graph 3 on page 91 for pressure
drop and minimum flow rate through the boiler.
Sizing Primary Piping
See Figure 9 through Figure 15, page 22 and
following, for recommended piping arrange-
ments based on various applications. Size the
piping and system components required in
the space heating system, using recognized
design methods.
GF-125