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Benchmark 750-3000 Boiler Installation & Startup Manual
SECTION 5 – SAFETY DEVICE TESTING
5.2 LOW GAS PRESSURE TEST
Complete the instructions in Section 5.2.1 for BMK 750 – 2500 units, or in Section 5.2.2 for BMK
3000 units, which have different Low and High Gas Pressure switches.
5.2.1 LOW GAS PRESSURE TEST: BMK 750 – 2500
To simulate a low gas pressure fault, refer to Figure 5-1a, 5-1b or 5-1c and perform the
following steps:
LOW Gas Pressure Test Instructions: BMK 750 – 2500
1. Close the leak detection ball valve located at the Low Gas Pressure switch.
2. Remove the 1/4" NPT plug from the ball valve at the Low Gas Pressure switch.
3. Install a 0 - 16" W.C. (0 – 4.0 kPa) manometer or gauge where the 1/4" plug was removed.
4. Slowly open the ball valve near the Low Gas Pressure switch.
5. Press the MENU key on the front panel of the C-More Controller and access the Setup
menu, enter the password 6817 and then press the ENTER key.
6. Place the unit in MANUAL mode and adjust the Air/Fuel Valve position (% open) between
25% and 30%.
7. While the unit is firing, slowly close the external manual gas shut-off valve (not shown).
8. The unit should shut down and display a GAS PRESSURE fault message at approximately
the pressure shown in Table 5-1 (the pressure setting of the LOW Gas Pressure switch):
TABLE 5-1: LOW Gas Pressure ± 0.2" W.C. (± 50 Pa)
Benchmark Model
BMK 750/1000 FM & DBB Single-Fuel
BMK 1500/2000 FM & DBB Single-Fuel
BMK 1500/2000 Dual-Fuel
BMK 1500/2000 DBB Dual-Fuel
BMK 2500 FM & DBB Single-Fuel
BMK 2500 Dual-Fuel
BMK 2500 DBB Dual-Fuel
BMK 3000 FM & DBB Single-Fuel
BMK 3000 Dual-Fuel
BMK 3000 DBB Dual-Fuel
9. Fully open the external manual gas shut-off valve (not shown) and press the CLEAR
button on the C-More Controller.
10. The fault message should clear and the FAULT indicator should go off. The unit should
restart.
11. Upon test completion, close the ball valve and remove the manometer. Replace the 1/4"
NPT plug removed in step 2.
OMM-0121_D • GF-205 • 5/9/2019
Natural Gas
2.6" W.C. (648 Pa)
3.6" W.C. (897 Pa)
4.4" W.C. (1,096 Pa)
2.6" W.C. (648 Pa)
3.6" W.C. (897 Pa)
7.5" W.C. (1,868 Pa)
7.5" W.C. (1,868 Pa)
2.6" W.C. (648 Pa)
7.5" W.C. (1,868 Pa)
7.5" W.C. (1,868 Pa)
Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
Propane
7.5" W.C. (1,868 Pa)
–
2.6" W.C. (648 Pa)
2.6" W.C. (648 Pa)
–
3.6" W.C. (897 Pa)
3.6" W.C. (897 Pa)
–
2.6" W.C. (648 Pa)
2.6" W.C. (648 Pa)
Page 78 of 122
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