AERCO BMK 2.0 LN Dual Fuel Nov 2010 - Manual (Page 54)

SAFETY DEVICE TESTING
WATER TEMP SWITCH OPEN fault
message should be displayed. It should not
be possible to restart the unit.
4. Reset the adjustable over-temperature
switch to its original setting.
5. The unit should start once the adjustable
temperature limit switch setting is above the
actual outlet water temperature.
6.8 INTERLOCK TESTS
The unit is equipped with two interlock circuits
called the Remote Interlock and Delayed
Interlock. Terminal connections for these circuits
are located in the I/O Box (Figure 2-9) and are
labeled REMOTE INTL’K IN and DELAYED
INTL’K IN. These circuits can shut down the
unit in the event that an interlock is opened.
These interlocks are shipped from the factory
jumpered (closed). However, each of these
interlocks may be utilized in the field as a remote
stop and start, an emergency cut-off, or to prove
that a device such as a pump, gas booster, or
louver is operational.
6.8.1 REMOTE INTERLOCK
1. Remove the cover from the I/O Box and
locate the REMOTE INTL’K IN terminals.
2. Start the unit in the Manual Mode and set
the valve position to 34%.
3. If there is a jumper across the REMOTE
INTL’K IN terminals, remove one side of the
jumper. If the interlock is being controlled by
an external device, either open the interlock
via the external device or disconnect one of
the wires leading to the external device.
4. The unit should shut down and display
INTERLOCK OPEN.
5. Once the interlock connection is
reconnected, the INTERLOCK OPEN
message should automatically clear and the
unit should restart.
6.8.2 DELAYED INTERLOCK
1. Remove the cover from the I/O Box and
locate the DELAYED INTL’K IN terminals.
2. Start the unit in the Manual Mode at a valve
position between 25% and 30%.
3. If there is a jumper across the DELAYED
INTL’K IN terminals, remove one side of the
jumper. If the interlock is connected to a
proving switch of an external device,
disconnect one of the wires leading to the
proving switch.
4. The unit should shut down and display a
DELAYED INTERLOCK OPEN fault
message. The FAULT LED should be
flashing.
5. Reconnect the wire or jumper removed in
step 3 to restore the interlock.
6. Press the CLEAR button to reset the fault.
7. The unit should start.
6.9 FLAME FAULT TESTS
Flame faults can occur during ignition or while
the unit is already running. To simulate each of
these fault conditions, proceed as follows:
1. Set the ON/OFF switch to the OFF position.
2. Place the unit in the Manual Mode and set
the valve position to 34%.
3. Close the manual gas shutoff valve located
between the Safety Shut-Off Valves
(SSOVs) and the Air/Fuel Valve (see Figure
6-3).
4. Set the ON/OFF switch to the ON position to
start the unit.
5. The unit should shut down after reaching the
Ignition cycle and display FLAME LOSS
DURING IGN.
6. Open the valve previously closed in step 3
and press the CLEAR button.
7. Restart the unit and allow it to prove flame.
8. Once flame is proven, close the manual gas
valve located between the SSOV and the
Air/Fuel Valve.
9. The unit should shut down and execute an
IGNITION RETRY cycle by performing the
following steps:
(a) The unit will execute a shutdown purge
cycle for a period of 15 seconds and
display WAIT FAULT PURGE.
(b) The unit will execute a 30 second re-
ignition delay and display WAIT RETRY
PAUSE.
(c) The unit will then execute a standard
ignition sequence and display WAIT
IGNITION RETRY
.
6-4