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Benchmark 5000-6000 Boiler Installation & Startup Manual
SECTION 3: START SEQUENCE
When there is a demand for heat, the following events will occur:
Start Sequence
1. The DEMAND LED status indicator will light.
2. The unit checks to ensure that the Proof of Closure (POC) switch in the downstream Safety
Shut-Off Valve (SSOV) is closed. See Figure 3-1 for SSOV location.
TO AIR/FUEL
VALVE
MANUAL SHUT-
OFF VALVE
HIGH GAS
PRESSURE SWITCH
- BMK 6000: 10.5" W.C., 2.6 kPa
- BMK 5000: 11.0" W.C., 2.7 kPa
3. With all required safety device switches closed, a purge cycle will be initiated and the
following events will occur:
a. The Blower relay energizes and turns on the blower.
b. The Air/Fuel Valve rotates to the full-open purge position and closes purge position
switch. The dial on the Air/Fuel Valve (Figure 3-2) will read 100 to indicate that it is
full-open (100%).
c. The VALVE POSITION bargraph will show 100%.
OMM-0123_E • GF-207 • 12/17/2019
DOWNSTREAM
SSOV WITH
POC
Figure 3-1: SSOV Location
Figure 3-2: Air/Fuel Valve In Purge Position
Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
UPSTREAM
SSOV
UPSTREAM LOW GAS
PRESSURE SWITCH
- BMK 6000: 8.5" W.C., 2.1 kPa
- BMK 5000: 8.0" W.C., 2.0 kPa
TO BLOWER
AIR IN
GAS INLET
STEPPER
MOTOR
Page 38 of 95
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