Watts AERCO Benchmark 2.0LN, Operating & Maintenance Instructions

Page: 42 / 101

SAFETY DEVICE TESTING
6-1
Chapter 6 - SAFETY DEVICE TESTING PROCEDURES
6.1 TESTING OF SAFETY DEVICES
Periodic safety device testing is required to
ensure that the control system and safety
devices are operating as designed. The
AERCO control system comprehensively
monitors all combustion related safety devices
before, during and after the start sequence. The
following tests have been chosen to ensure that
the system will either not start or will shut-down
as intended.
Operating and safety controls should be tested
on a regular basis or after a safety device has
been serviced or replaced. All testing must
conform to local codes such as ASME CSD-1.
NOTE:
MANUAL and AUTO modes are required to
perform the following tests. For a complete
explanation of these modes, see Chapter 3.
NOTE:
It will be necessary to remove the sheet
metal covers from the unit to perform the
following tests.
WARNING!
ELECTRICAL VOLTAGES IN THIS
SYSTEM MAY INCLUDE 460, 220, 120
AND 24 VOLTS AC. POWER MUST BE
REMOVED PRIOR TO PERFORMING
WIRE REMOVAL OR OTHER TESTING
PROCEDURES THAT CAN RESULT IN
ELECTRICAL SHOCK.
6.2 LOW GAS PRESSURE FAULT TEST
1. Referring to Figure 6.1, ensure that the 1/8"
NPT ball valve upstream of the SSOV is
closed (located at low gas pressure switch).
2. Remove the 1/8" plug from the ball valve,
upstream of the safety shutoff valve (SSOV).
3. Install a 0-16" W.C. manometer or W.C.
gauge where the 1/8" plug was removed.
4. Slowly open the 1/8" ball valve upstream of
the SSOV.
5. Place the unit in Manual Mode and fire the
unit at a firing rate between 25% and 30%.
6. While the unit is firing, slowly close the Man-
ual gas shut-off valve located immediately
outside the boiler. The unit should shut
down on a LOW GAS PRESSURE fault
message at 4.4” W.C. For Benchmark 2.0
Low NOx boilers configured for De-Rated
capacity (see para. 2.4.1), the unit should
shut down on a LOW GAS PRESSURE fault
message at 3.6” W.C.
SSOV
HIGH GAS
PRESSURE
SWITCH
LOW GAS
PRESSURE
SWITCH
1/8" NPT PLUG
(INSTALL
MANOMETER
HERE)
Figure 6.1
1/8” Pipe Plug Position for Manometer
Installation & Low Gas Pressure Testing
7. Fully open the manual gas shut-off valve
and press the CLEAR button on the Control
Box.
8. The unit should restart.
9. Remove manometer and replace 1/8”NPT
plug.
NOTE:
After faulting the unit, the fault message will
be displayed and the fault indicator light will
flash until the CLEAR button is pressed.
6.3 HIGH GAS PRESSURE TEST
1. Start the unit in manual mode and fire
between 25% and 30%.
2. Remove either wire # 150 or wire #151 from
the high gas pressure switch. See Fig. 6.1.
3. The unit should shut down on a HIGH GAS
PRESSURE FAULT .