Benchmark 750-3000 Installation & Startup Manual
SECTION 4
– INITIAL START-UP
OMM-115_D
•
GF-200
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5/9/2019
Technical Support
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4.7 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
button. These controls are mounted on a plate as shown in Figure 4-6a
and 4-6b. 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 Figure 4-6a and 4-6b before the boiler can be restarted.
The adjustable
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 Figure 4-6a, 4-6b and 4-7 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 4.7.1.
Figure 4-6a: BMK 750 & 1000 Over-Temperature Limit Switch Location
Figure 4-6b: BMK 1500
– 3000 Over-Temperature Limit Switch Location
MANUAL TEMPERATURE LIMIT
SWITCH
DIGITAL OVER-
TEMPERATURE
LIMIT CONTROLLER
RESET BUTTON FOR MANUAL
TEMPERATURE LIMIT SWITCH
MANUAL
TEMPERATURE
LIMIT SWITCH
ADJUSTABLE
TEMPERATURE
LIMIT SWITCH
(AUTO-REST)
DIGITAL OVER-TEMPERATURE
LIMIT CONTROLLER
ADJUSTABLE TEMPERATURE
LIMIT SWITCH (AUTO-REST)
RESET BUTTON FOR MANUAL
TEMPERATURE LIMIT SWITCH
