FULTON VSRT Series Installation, Operation And Maintenance Manual page 68

OPERATION
2. Do not introduce steam to the system until the
boiler has been properly boiled out. A separate line
discharged to a safe location is recommended for steam
discharge prior to boil out completion.
3. On new systems, send condensate returns to the drain
to ensure the new system piping has been flushed free
of debris and is fully clean. If debris filled condensate is
not wasted, additional boil-out(s) may be required.
Sequence of Operation: Gas Fired
Burners
The burner is of forced draft design. The Sequence of
Operation for the burner is as follows:
1. Check main gas valve, which provides proper pressure
to burner. Refer to Table 3 for maxiumum gas pressure.
A step-down regulator may be necessary.
2. Combustion air is delivered by a centrifugal blower fan.
An air switch monitors the pressure and is part of the
flame programmer safety interlock circuit.
* For 9.5, 80-250 HP - an air filter switch also monitors
to be sure that the air inlet filters are not clogged with
debris
3. The flame programmer monitors the safe operation
of the burner. Functions include pre-purge of the
combustion chamber, provision of ignition via the
ignition transformer and electrode, opening main gas
valves and providing post-purge of the combustion
chamber.
4. The flame is monitored by a flame sensor. In the event
of insufficient, unstable, or non existent pilot or main
flame, the flame sensor will cause a safety lockout of the
flame programmer. Safety lockout can also be caused if
the flame sensor is improperly positioned or grounded.
After fault has been corrected, reset by pressing the
appropriate reset button on the boiler panel or the
burner controller.
ƒ Sequence of Operation: Modulated Burner
The burner is equipped with modulating controls, which will
provide up to a 10:1 turndown of the burner (dependent on
Boiler HP). This system is linkageless, and operates a fuel control
valve, an air control valve and a variable speed drive to achieve
turndown.
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VSRT-IOM-2022-0728
Beginning from an off state, and assuming there is a load on
the system (call for heat), when turning the switch to on, the
following will be the sequence of operations.
1. The flame programmer will engage the blower motor
and begin to open the air butterfly to the purge
position. The air switch will prove flow, and once all
devices are in purge position/speed, and the air switch
is made, the flame programmer will begin to count
down the specified purge time (30 seconds).
2. Once purge is completed, the control will drive the
blower speed, the air butterfly and the gas butterfly to
the ignition position.
3. Once all devices are stable, the control will energize the
ignition transformer, followed by opening the pilot gas
valve, igniting the pilot flame.
4. Once pilot flame is established, the ignition spark will
de-energize, and the pilot flame must remain proven by
the scanner for a short safety time.
5. The main gas valve will now be energized, supplying
fuel to the burner, and lighting the main flame.
6. The pilot valve turns off, and the main flame must
remain proven by the scanner for a second short safety
time.
7. The control now releases to modulation. The firing
rate will now be dictated by the load on the system, as
measured by the pressure controller.
8. The burner output will vary from high fire down to low
fire continuously in order to match load.
9. Once the system load has been satisfied (steam
pressure in the system exceed setpoint) the burner will
initiate it's shutdown sequence.
10. If possible in time allotted (and if the system is set-up
and sized properly), the burner will modulate to low
fire before shutting down. Regardless of firing rate,
the shutdown begins with the main gas valve de-
energizing, stopping fuel flow to the burner.
11. The control will then drive air damper and the blower
to their specified post-purge position, after which it will
purge combustion gasses from the unit for 15 seconds.
12. The control will then de-energize the blower motor and
drive all gas and air dampers to their closed position
13. The burner will remain in the off state until the system
steam pressure falls below setpoint for the burner to
turn back on.
SECTION 3
© Fulton Group N.A., 2022