Over-Temperature Limit Switches - Watts AERCO Benchmark BMK750 Operation And Service Manual

Benchmark with Edge [I]: Operation-Maintenance 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 4-11a –
4-11c. 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 4-11a – 4-11c 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 4-11a – 4-11c and Figure 4-12 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 4-11a: BMK750 & 1000 Over-Temperature Limit Switch Location
Figure 4-11b: BMK1500 – 4000 Over-Temperature Limit Switch Location
OMM-0145_A99 • GF-218 •
MANUAL
TEMPERATURE
LIMIT SWITCH
ADJUSTABLE
TEMPERATURE
LIMIT SWITCH
(AUTO-REST)
Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
9/18/2019
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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