750-96 (revised 2010)
Model CB Packaged Boiler Manual
4-11
4.9 — Firing Preparations for Gas: Series 200-300-400-700-900
Determine that sufficient pressure exists at the entrance to the gas train. This can be done by installing a test
gauge downstream of the regulator.
The gas pressure regulator must be adjusted to the proper pressure level. Since this regulator is generally sup-
plied by others, adjustment should proceed according to instructions supplied by its manufacturer.
It is necessary for the operator to know the burner requirements in gas quantity and pressure. This information can
generally be found on the dimension diagram supplied for the particular installation. Should this information not be
readily available, consult the Cleaver-Brooks Service Department and provide the boiler serial number. Chapter 5
contains additional information along with standard gas flow and pressure requirements. This section should be
completely reviewed prior to startup.
If the burner is a combination fuel model, set the gas/oil switch to “gas.” Withdraw the oil burner gun and latch it in
its rearward position.
On initial startup, it is recommended that the main gas shutoff cock remain closed until the programmer has
cycled through pre-purge and pilot sequences. When the fuel oil light on the control panel comes on, observe the
action of the motorized gas valve stem to determine that it opens when energized. As soon as this is confirmed,
turn the burner switch “off” and let the programmer finish its cycle. Check to see that the gas valve has closed.
Again turn the burner “on” and when the fuel valve light glows slowly open the main gas cock. Main flame should
ignite unless there is air present in the line. If flame is not established within about 5 seconds, turn the burner
switch “off” and allow the programmer to recycle normally for a new lighting trial. Several efforts may be neces-
sary to “bleed” air from the line.
Once the main flame is established, observe that it is extinguished promptly when the burner is shut down. The
flame may continue to burn for a second or two after normal shutdown due to the gas remaining downstream from
the fuel valve. If the flame continues to burn for a longer period or during blower motor spindown, immediately turn
the burner switch off and close the main gas cock. Investigate and correct the cause of valve leakage before
relighting the burner. The main gas valve is tight seating provided nothing prevents tight closure. Foreign material
may be present in either new or renovated gas lines unless adequate care is taken in cleaning and purging.
When the conditions covered above and in Sections 4.1, 4.2, and 4.3 are assured, the burner is ready for firing.
Refer to Section 4.10 for further starting and operating information.
Do not repeat unsuccessful lighting attempts without re-checking burner and pilot adjustments if lighting does not
occur within 5 seconds after fuel introduction is verified or can be reasonably assumed.
NOTE: The burner and control system is designed to provide a “pre-purge” period of fan operation prior to establishing
ignition spark and pilot flame. Do not attempt to alter the system or to take any action that might circumvent this fea-
ture.
Courtesy of: C3 Surplus LLC
Surplus Industrial Superstore
305-428-2777
https://www.c3surplus.com
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