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Benchmark 2500DF-3000DF Installation, Operation & Maintenance Manual
Switchover from Propane Gas to Natural Gas – Continued
16. Press the CHANGE key. Fuel Type will begin to flash.
17. Press the ▼ arrow key. Natural Gas will be displayed.
18. Press the ENTER key to store the Natural Gas Fuel type.
19. Replace the front door panel.
20. This completes the steps necessary to switch from Propane Gas to Natural Gas
operation.
4.7 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 4-7. 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 4-7 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 Figure 4-7 and 4-8 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 4.7.1.
RESET BUTTON FOR MANUAL
TEMPERATURE LIMIT SWITCH
Figure 4-7: Over-Temperature Limit Switch Locations
4.7.1 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 4-8 and Table 4-1.
Page 66 of 234
05/21/2014
CHAPTER 4 – INITIAL START-UP
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913
Phone: 800-526-0288
DIGITAL OVER-TEMPERATURE
ALARM SWITCH
ADJUSTABLE TEMPERATURE
LIMIT SWITCH
MANUAL TEMPERATURE LIMIT
SWITCH
OMM-0099_0A
GF-145
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