Additional Limit Control; Backflow Preventer; Boiler System Piping Applications; Fig. 7 - Near Boiler Piping - Diaphragm Expansion Tank - TriangleTube PRESTIGE Excellence 110 Installation & Maintenance Manual

CHAPTER 4 - BOILER PIPING
4.5.

Additional Limit Control

If a separate Low Water Cut Off (LWCO) is required by
the local jurisdiction or when the boiler is installed
above the system piping, the following guidelines
must be followed:
• The LWCO must be designed for water installations,
electrode probe-type is recommended.
• The LWCO must be installed in a tee connection on
the boiler supply piping above the boiler.
• Wiring of the LWCO to the PRESTIGE Excellence is
done directly onto the low voltage terminal strip.
Reference Fig. 16 on page 30 for available exter-
nal limit (manual or auto reset) terminals.
If the installation is to comply with ASME or Canadian
requirements, an additional high temperature limit
may be required. Consult local code requirements to
determine compliance. The limit should be installed as
follows:
• Install the limit in the boiler supply piping between
the boiler and any isolation valve.
• Consult heat exchanger for maximum temperature
set point.
• For wiring of the limit, reference Fig. 16 on page
30. Wire the limit to the manual reset terminals
on the low voltage terminal strip. An open manual
reset limit will require a manual reset of the control.
System
Supply
4.6.
Use a backflow preventer valve in the make-up water
supply to the unit as required by local codes.
4.7.
Boiler Boiler
Supply Return
12"
Max.

Fig. 7 - Near Boiler Piping - Diaphragm Expansion Tank

Backflow Preventer

Boiler System Piping Applications

BEST PRACTICE
• It is recommended on all piping applica-
tions to utilize a primary/secondary piping
arrangement as a means to provide freeze
protection of the boiler, which is an integral
function of the boiler control. Maintain at
least the minimum boiler flow rate shown
in Graph 1 on page 81. For other piping
arrangements, contact ACV-Triangle Tube
Technical Support or consult other ap-
proved/recognized design arrangements.
• On piping applications utilizing a single zone
or other recognized piping design arrange-
ments, it is recommended that the installer
uses flow/check valves with weighted seats
at or near the PRESTIGE Excellence to prevent
gravity circulation.
System
Return
Cold
Water
Fill
15