AERCO Esteem Boiler with EZ-Set Controller - Manual (Page 33)

GF-135
Esteem 399 Low NOx Boiler Chapter 5
OMM-0089_0A Installation, Operation & Maintenance Manual Boiler Piping
5.5 ADDITIONAL LIMIT CONTROL
If a separate LWCO device is required by certain local jurisdictions or when the boiler is
installed above the system piping, the following guidelines must be followed:
• The LWCO device must be designed for water installations, electrode probe-type is
recommended.
• The LWCO device must be installed in a tee connection on the boiler supply piping above
the boiler.
• Wiring of the LWCO device to the Esteem boiler is done directly onto the 24V terminal
strip. See Figure 8-3 for available terminals for an external limit (manual or auto reset).
If the installation is to comply with ASME or Canadian requirements, an additional high
temperature limit may be needed. 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 set point of limit.
• For wiring of the limit, see Figure 8-3 for using the external limit/manual reset terminals
on the 24V terminal strip. This will provide a “hard” lockout requiring a manual reset of the
control.
5.6 BACKFLOW PREVENTER
Use a backflow preventer valve in the make-up water supply to the unit as required by local codes.
5.7 BOILER SYSTEM PIPING APPLICATIONS
NOTE
It is recommended on all piping applications 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 the minimum
boiler flow rate (see the charts in Figure B-1 and B-2 in Appendix B). For
other piping arrangements, consult the Engineering Department at AERCO
International or consult other approved/recognized design arrangements.
NOTE
On piping applications utilizing 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.
5.8 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 boiler and the system volume and temperature.
WARNING!
Undersized expansion tanks will cause system water to be lost
through the pressure relief valve and cause additional 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 5-3 and Figure 5-4 when using a
Page 33 of 188 AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 OMM-0089_0A
MC1 06/19/14 Ph.: 800-526-0288