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Benchmark 750-3000 Installation & Startup Manual
SECTION 4 – INITIAL START-UP
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
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OMM-115_D
GF-200
5/9/2019
MANUAL
TEMPERATURE
LIMIT SWITCH
ADJUSTABLE
TEMPERATURE
LIMIT SWITCH
(AUTO-REST)
Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
126
RESET BUTTON FOR MANUAL
TEMPERATURE LIMIT SWITCH
DIGITAL OVER-
TEMPERATURE
LIMIT CONTROLLER
DIGITAL OVER-TEMPERATURE
LIMIT CONTROLLER
ADJUSTABLE TEMPERATURE
LIMIT SWITCH (AUTO-REST)
RESET BUTTON FOR MANUAL
TEMPERATURE LIMIT SWITCH
MANUAL TEMPERATURE LIMIT
SWITCH
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