Burnham Series 5B - Manual (Page 58)

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Pilots, after ignition of pilot flame will close
the pilot valve and the main gas valves
controlled by that particular RM7890A relay
in 0.8 second. The burners controlled by the
other RM7890A will continue to burn.
(b) For 15 seconds after failure of a Q179C
pilot, the relay through terminals #8 and #10
will attempt to re-establish pilot flame. If no
pilot flame can be sensed by the flame rod
circuit in 15 seconds, terminals #8 and #10
are de-energized, and the relay will lock out
on safety.
(c) Pilot failure is caused by the following:
(1) Complete loss of gas supply.
(2) Poor ignition spark caused by low
voltage, poor ground connection, faulty
wiring, and possibly a defective ignition
transformer.
(3) Low gas pressure will prevent flame rod
circuit from sensing pilot flame properly.
(4) Unusually strong secondary air drafts
can blow the pilot flame away from the
flame rod momentarily causing nuisance
shutdown.
(5) A pilot line solenoid valve will not open
because of faulty wiring, low voltage, or
possibly the valve is defective.
(6) A defective RM7890A may be the cause
but items (1) thru (5) should be followed
first. Refer also to RM7890A relay
literature furnished with the control.
(d) By referring to the Sequence of Operations
step by step operation of the system can
be controlled and the cause of pilot failure
can be readily found. After the cause of
pilot failure has been corrected, resume
normal operation by following the Lighting
Instructions.
(3) SHUTDOWN INSTRUCTIONS
(a) Close manual shut-off valves and pilot
valves.
(b) Turn off main electric switch.
13. THERMOCOUPLE CONTROL SYSTEM (Canada
Only)
The 5006B thru 5013B boilers are equipped with
a Thermocouple Control System that utilizes a
constant-burning Q327A pilot, a Q309 thermocouple,
and a L62GB-3C Pilot Safety Switch. The Q309
thermocouple proves pilot flame and, in the absence
of such, will cool and, within 45 to 90 seconds, will
cause the L62GB-3C Pilot Safety Switch to which it is
connected, to break the electrical circuit to the main gas
valves as well as shut off the flow of gas to the pilot.
Thus, 100% shut-off is achieved.
The 5015B thru 5024B boilers utilize two
Thermocouple Control Systems that are interconnected
electrically thru all operating and safety controls.
Should any of the aforementioned controls break the
power supply circuit, both Thermocouple Control
Systems would be de-energized. The proceeding
paragraph describes the function and operation of each
Thermocouple Control System. Should a pilot failure
on one Thermocouple Control System occur, the other
Thermocouple Control System would not be affected.
Thus main burners on the unaffected side would ignite
on a “call for heat” and would continue to operate until
the operating control was satisfied.
a. LIGHTING INSTRUCTIONS
(1) Make sure that all main manual and pilot valves
have been off for at least five (5) minutes.
(2) Set operating and limit controls to desired
setting.
(3) Open pilot valve.
(4) Depress button on pilot safety switch to which
it is connected and hold lighted match on pilot.
Hold button in for at least one minute, or until
the pilot burner remains lit after the button is
released. Repeat for second pilot when boiler is
so equipped.
(5) Open manual main shut-off valve(s).
(6) Turn on main electric switch.
NORMAL OPERATION SEQUENCE
5006B thru 5013B, see Fig. 50
5015B thru 5024B, see Fig. 51
SecTiON iV - OPeRATiON (continued)