Benchmark 750-3000 Installation & Startup Manual
SECTION 5
– SAFETY DEVICE TESTING
OMM-115_D
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5/9/2019
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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
Natural Gas
Propane
BMK 750/1000 FM & DBB Single-Fuel
2.6” W.C. (648 Pa)
7.5
” W.C. (1,868 Pa)
BMK 1500/2000 FM & DBB Single-Fuel
3.6” W.C. (897 Pa)
–
BMK 1500/2000 Dual-Fuel
4.4” W.C. (1,096 Pa)
2.6” W.C. (648 Pa)
BMK 1500/2000 DBB Dual-Fuel
2.6” W.C. (648 Pa)
2.6” W.C. (648 Pa)
BMK 2500 FM & DBB Single-Fuel
3.6” W.C. (897 Pa)
–
BMK 2500 Dual-Fuel
7.5” W.C. (1,868 Pa)
3.6” W.C. (897 Pa)
BMK 2500 DBB Dual-Fuel
7.5” W.C. (1,868 Pa)
3.6” W.C. (897 Pa)
BMK 3000 FM & DBB Single-Fuel
2.6” W.C. (648 Pa)
–
BMK 3000 Dual-Fuel
7.5” W.C. (1,868 Pa) 2.6” W.C. (648 Pa)
BMK 3000 DBB Dual-Fuel
7.5” W.C. (1,868 Pa) 2.6” W.C. (648 Pa)
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.
