Sequence Of Operation; Heater Lockout Indication; Commissioning And Testing; Figure 30: Burner Sequence Of Operation Chart - Roberts Gorden CoRayVac CRT-10 Installation, Operation & Service Manual

Figure 30: Burner Sequence of Operation Chart

KEY TO
SYMBOLS
Thermostat
Neon
Ignition
Gas
Valve
Flame
Sensing
Lockout Alarm
(optional)

12.1 Sequence of Operation

On connection of the power supply, the pump will
start creating a suction in the tube. The pressure
switch at the pump will change contacts when suc-
tion is created. A pre-purge cycle which lasts 30 sec-
onds is initiated. Once complete, power to the
burners is enabled.
The burner sequence begins with the red lockout
neon illuminated. This indicates that the burner has
begun the ignition sequence.
Power to the burner sequence controller initiates an
approximate 45 second purge period. Following the
purge period, the solenoid valve opens. This allows
the vacuum, created in the tube, to lift the diaphragm
in the zero governor thereby allowing the passage of
gas to the burner. At the same time, a spark is cre-
ated and ignition should take place. If ignition of the
gas is not successful, the spark will cease and the
solenoid will close after approximately 10 seconds.
The ignition sequence is repeated for 2 more times
before lockout occurs. The lockout neon will remain
lit indicating the condition. When the gas is ignited,
the detection circuit is energised and switches off
the ignition circuit. The run neon (green) will illumi-
nate indicating full running condition.
The system will continue to run until the power sup-
ply or gas supply is interrupted. Interruption of the
electrical supply results in shutdown of the burners,
after which, the pump will continue to run for two
T 0 T 1 T 2
Lockout
Start/Run
T S
10
sec
55 sec approx.
SECTION 12: O
T 3 T 4 T 5 T 6
T S
45 10
sec sec
Interuption of main
minutes to clear products of combustion from the
system. Restoration will restart the whole sequence.
Interruption of the gas supply will result in loss of
flame followed by 3 attempts to reignite, if unsuc-
cessful, lockout occurs. See Page 41, Figure 30 for
alarm sequence.

12.2 Heater Lockout Indication

In case of flame loss during operation of the heater,
the burner control unit goes to lockout mode after
three ignition trials. At this stage a 230 V signal is
provided which enables the ROBERTS GORDON
controller, BMS sytem, etc. to indicate precisely
which heater has failed. If your heater is equipped
with "Heater Lockout" indication, an additional wire
has to be installed from the heater's lockout indicator
connector to the monitoring computer.

12.3 Commissioning and Testing

Commissioning of the system must be carried out by
a registered installer/contractor qualified in the
installation and service of gas-fired heating equip-
ment or your gas supplier.
1. Establish that a satisfactory purged gas supply
and an electrical supply is available to the
heater.
M
PERATION AND AINTENANCE
T 7
3 try
flame sensing
41 of 54
T 8
®