Watts AERCO Benchmark BMK750 Operation And Service Manual page 34

Benchmark with Edge [I]: Operation-Maintenance Manual
SECTION 3 - START SEQUENCE
Start Sequence
TO AIR/FUEL
VALVE
MANUAL SHUT-
OFF VALVE
PRESSURE SWITCH
- BMK6000: 10.5" W.C., 2.6 kPa
- BMK5000: 11.0" W.C., 2.7 kPa
3. The Auxiliary Delay occurs for a configurable length of time and the Delayed Interlocks are closed.
4. Once all required safety device switches are closed, a purge cycle is initiated and the following
events 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 3-2a and 3-2b) will read 100 to indicate
that it is full-open (100%).
The Fire Rate bargraph on the Controller's front face shows 100%.
c.
Figure 3-2a: BMK750 & 1000 Air/Fuel Valve in Purge Position
OMM-0145_A99 • GF-218 •
DOWNSTREAM
SSOV WITH
POC
HIGH GAS
Figure 3-1e: BMK5000-6000: SSOV Location
AIR INLET
100
Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
9/18/2019
UPSTREAM
SSOV
UPSTREAM LOW GAS
PRESSURE SWITCH
- BMK6000: 8.5" W.C., 2.1 kPa
- BMK5000: 8.0" W.C., 2.0 kPa
STEPPER MOTOR
GAS INLET
TO
BLOWER
Page 34 of 157