Benchmark 2500 - 3000 Boilers
CHAPTER 4 – INITIAL START-UP
OMM-0094_0F
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
Page
63
of
207
GF-137
Ph.: 800-526-0288
09/30/2015
4.5 OVER-TEMPERATURE LIMIT SWITCHES
The unit contains three (3) types of over-temperature limit controls. These controls consist of a
Manual Reset button, a rotary adjustable Temperature Limit switch and a digital Over-
Temperature Alarm switch. These controls are mounted on a plate as shown in Figure 4-5. They
can be accessed by opening the front panel door of the unit.
The Manual Reset button is not adjustable and is permanently fixed at 210°F (98.9°C). This
button will shut down and lock out the boiler if the water temperature exceeds 210°F (98.9°C).
Following an over-temperature condition, it must be manually reset by pressing the manual
reset button shown in Figurer 4-4 before the boiler can be restarted.
The rotary adjustable Over- Temperature Limit switch is manually adjustable from 32ºF - 212ºF
(0ºC – 100ºC). This switch allows the boiler to restart, once the temperature drops below the
selected temperature setting on the dial. Set the dial on this switch to the desired setting.
The digital Over-Temperature Alarm switch shown in Figures 4-5 and 4-6 is preset at the factory
to 210ºF (98.9°C) 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 can be checked or adjusted using the procedure in section 4.5.1.
Figure 4-5: Over-Temperature Limit Switch Locations
4.5.1 Over-Temperature Alarm Switch Checks and Adjustments
The digital
Over-Temperature
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 4-8.
F
Alarm
RST
SET
Limit Control
Figure 4-6: Digital Over-Temperature Alarm Switch Front Panel
DIGITAL OVER-TEMPERATURE
ALARM SWITCH
ADJUSTABLE OVER-
TEMPERATURE LIMIT SWITCH
MANUAL RESET BUTTON FOR
TEMPERATURE LIMIT SWITCH
MANUAL TEMPERATURE LIMIT
SWITCH