Benchmark 750/1000 Boiler Installation, Operation & Maintenance Manual
CHAPTER 4 – INITIAL START-UP
OMM-0082_0J
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
Page
65
of
192
GF-130
Ph.: 800-526-0288
05/21/2014
Reassembly After Combustion Calibration – Continued
5.
Remove the combustion analyzer probe from the 1/4” vent hole in the exhaust manifold.
Replace the 1/8” NPT plug in the manifold.
6.
Replace all previously removed sheet metal enclosures on the unit.
4.6 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 4-4. The switches can be accessed by
removing the unit front panel from 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 4-4 before the boiler can be restarted.
The rotary dial 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 over-temperature switch to the desired
setting.
The digital alarm switch shown in Figures 4-5 and 4-6 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 4.5.1.
