Reassembly; Over-Temperature Limit Switches - Watts Aerco BENCHMARK 750 User Manual

Benchmark 750 – 1000 Boiler User Manual - INTERNATIONAL

4.4 REASSEMBLY

Once the combustion calibration adjustments are properly set, the unit can be reassembled for
service operation.
1. Set the ON/OFF switch in the OFF position.
2. Disconnect AC power from the unit.
3. Shut off the gas supply to the unit.
4. Remove the manometer and barbed fittings and reinstall the NPT plug using a suitable
pipe thread compound.
5. Remove the combustion analyzer probe from the 1/4" vent hole in the exhaust manifold.
Replace the 1/4" NPT plug in the manifold.
6. Replace all previously removed sheet metal enclosures on the unit.
7. This concludes reassembly of the unit after combustion calibration.

4.5 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 4-5. 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 Heating 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 Figurer 4-5 before the Heating Boiler can be restarted.
The adjustable Temperature Limit switch is manually adjustable from 32ºF - 212ºF (0ºC –
100ºC). This switch allows the Heating 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 Figures 4-5 and 4-6 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 Heating Boiler and sounds an audible alarm. If desired, the
Over-Temperature Alarm can be checked or adjusted using the procedure in section 4.5.1.
Figure 4-5: Over-Temperature Limit Switch Locations
Page 62 of 170
11/03/2016
CHAPTER 4 – INITIAL START-UP
Reassembly
Manual
Temperature
Limit Switch
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913
Ph.: 800-526-0288
Reset button for
Manual Temperature
Limit Switch
Adjustable
Temperature Limit
switch (auto-rest)
Digital Over-
Temperature Limit
Controller
OMM-0119_0A
GF-130-I