Benchmark 2500 - 3000 Boilers
CHAPTER 4 – INITIAL START-UP
OMM-0094_0E
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
Page
61
of
204
GF-137
Ph.: 800-526-0288
03/20/2014
4.5 OVER-TEMPERATURE LIMIT SWITCHES
The unit contains three (3) types of over-temperature limit switches. These switches consist of a
manual reset switch, a rotary dial adjustable switch and a digital alarm switch. These switches
are mounted on a plate as shown in Figure 4-5. The switches can be accessed by opening the
front panel door of the unit.
The manual reset switch is not adjustable and is permanently fixed at 210°F. This switch will
shut down and lock out the boiler if the water temperature exceeds 210°F. Following an over-
temperature condition, it must be manually reset by pressing the manual reset button shown in
Figurer 4-5 before the boiler can be restarted.
The rotary dial over-temperature switch is manually adjustable from xxx to yyy ºF. This switch
allows the boiler to restart, once the temperature drops below the selected temperature setting
on the dial. Set the dial on this over-temperature switch to the desired setting.
The digital alarm switch shown in Figures 4-5 and 4-6 is preset at the factory to 210ºF and
should not be changed. If an over-temperature condition is detected, this switch automatically
shuts down the boiler and sounds an audible alarm. If desired, the over-temperature alarm
switch settings can be checked or adjusted using the procedure in section 4.5.1.
Figure 4-5: Over-Temperature Limit Switch Locations
4.5.1 Digital Alarm Switch Checks and Adjustments
The digital alarm switch settings can be checked or adjusted using the controls and display on
the front panel of the switch illustrated and described in Figure 4-6 and Table 4-1.
F
Alarm
RST
SET
Limit Control
Figure 4-6: Digital Over-Temperature Alarm Switch Front Panel
DIGITAL OVER-TEMPERATURE
ALARM SWITCH
ADJUSTABLE TEMPERATURE
LIMIT SWITCH
RESET BUTTON FOR MANUAL
TEMPERATURE LIMIT SWITCH
MANUAL TEMPERATURE LIMIT
SWITCH
