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9 Connecting the Heating Pipe
WARNING
Immediately repair any leaks in the system
plumbing to avoid the addition of make-up
water, make-up water provides a source of
oxygen and minerals that may lead to heat
exchanger failure to follow these instructions
will result in poor performance, unnecessary
wear of system components and premature
failure.
9.1 General Requirements
System Pressure
• The Combi Boiler is intended solely for use in
pressurized closed loop heating systems operating
with 12-30 psi water pressure at the Combi Boiler
outlet.
• To obtain the minimum system design pressure,
follow the piping diagrams illustrated in this
section.
• The Combi Boiler's Heating system is not
approved for operation in an "open system", thus
it cannot be used for direct potable water heating
or to process heating of any kind.
Backflow Preventer
Install a backflow preventer valve in the make-up
water supply to the unit as required by local codes.
Expansion Tank
An expansion tank must be installed in the heating
piping to prevent excessive from building in the
system.
See the examples of system application at the end
of this section for the installation location.
Refer to the expansion tank manufacturer's
instructions for additional details.
Follow the guidelines below when installing an
expansion tank.
• Connect an air separator to the expansion tank
only if the air separator is located on the suction
side of the system circulator.
• The Combi Boiler is equipped with an auto-
feeding water connection and motorized feeding
valve.
Therefore, installation of additional system water
fill connection is not necessary in most cases.
• If an additional water fill connection is required
for a specific use, install the water fill connection
at the same location as the expansion tank's
connection to the system.
• When replacing an expansion tank, consult the
expansion tank manufacturer's literature for
44
Connecting the Heating Pipe
proper sizing.
• For diaphragm expansion tanks, always install
an automatic air vent on the top side of the air
separator to remove residual air from the system.
Oxygen Elimination
This Combi Boiler may only be installed in a
pressurized closed-loop heating system, free of air
(oxygen) and other impurities.
To avoid the presence of oxygen, ensure all
of the air is removed from the system during
commissioning via strategically placed and
adequately sized air removal devices, located
throughout the heating system.
9.2 Low Water Cutoff (LWCO)
Internal of the Combi Boiler
• The Combi Boiler is equipped with a factory
installed, pressure sensor type low water cutoff
device.
• The lowest operation pressure for this device is 8
psi. (operation pressure = (default valve 12 psi) -
(4 psi))
The Combi Boiler performs water replenishment
automatically when the built-in water pressure
sensor detects insufficient water level in the
Combi Boiler system.
External of the Combi Boiler
• Low water cutoffs shall comply with the Safety
Standard for Limit Controls, ANSI/UL 353, or
the Standard for Temperature Indicating and
Regulating Equipment, CAN/CSA C22.2, No. 24,
as applicable. The following illustrates example of
typical LWCO installation.
• Install the probe above the minimum safe water
level.
NOTE This may be in a tapping on the Combi
Boiler or in the Combi Boiler supply or
return piping.
• Install the probe to extend into the Combi Boiler
cavity or piping to make contact with the water.
• Low water cutoffs shall be located so as to
provide adequate access for cleaning, repairing,
testing and inspection.
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