FTG │Installation & Operation Manual
Air Removal – The boiler and system plumbing layout must be configured to promote the removal of air from
the water. Air vents and bleeders must be strategically placed throughout the system to aid in purging the air
from the system during commissioning of the boiler. The system must also employ the use of a strategically
located air removal device, such as an air-scoop or micro-bubbler, designed to remove the air from the water
as it flows through the system.
Follow the installation instructions included with the air removal device when placing it
in the system; air removal devices generally work better when placed higher in the
system. Always locate air removal devices in areas of the system that have a guaranteed
positive pressure, e.g., in close proximity to the water fill and expansion tank.
Expansion Tank – The expansion tank must be sized in accordance with the water volume of the system as well
as the firing rate of the appliance. It is important to locate the expansion tank, and make-up water fill, on the
inlet side of any circulator in the system, as doing so will guarantee the lowest pressure in the system will be
at least equal to the tank and make-up water pressure. See examples in Figures 10-3 and 10-4.
Ensure the expansion tank cannot become isolated from the boiler anytime the system is
operating. The installation of flow checks, motorized valves or other shutoff devices
(other than for the purpose of servicing) are not permitted between the outlet of the boiler
and the expansion tank; see Figures 10-3 and 10-4. Failure to follow these instructions
may result in discharge of the Pressure Relief Valve resulting in property damage or
personal injury.
Indirect Water Heater (IWH) – When installed as per Figure 10-4, the indirect water heater is in series with the
boiler during a demand for DHW. Therefore, its head loss, along with the head loss of the boiler and
associated piping, must be considered when sizing the circulator.
Figures 10-3 and 10-4 illustrate typical piping systems. These piping schematics do not
illustrate all of the required concepts and components required to have a proper
installation. Concepts not shown include: prevention of thermal-siphoning (heat traps),
isolation valves, drain and purge valves, etc. It is the responsibility of the installing
contractor and system designer to determine which system best meets the need of the
installation and to consider all aspects of a proper system design. Contractor
modifications to these instructions may be required, based upon existing piping and
system design; consult NTI for required assistance (1-800-688-2575).
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