Burnham K50 Boiler User Manual


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54
toaQ309Thermocouple.TheRA890FProtectorelay
Primary Control is a non-programming, amplifying
relay which when used with the Q179D Pilot provides
solid state electronic Flame Safeguard Protection
during a “call for heat” pilot failure. Main burners
willshutdownwithin0.8secondandtheProtectorelay
will lock out on safety shutdown within 15 seconds.
Should a pilot failure occur during the “off” cycle, the
thermocouple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owofgastothe
pilot.Thus100%shut-offisachieved.
a. LIGHTING INSTRUCTIONS
(1) Make sure all Manual Main Shut-off Valves and
allPilotValveshavebeenoffforatleastve
minutes.
(2)
Set Operating and Limit Controls to desired
settings.
(3) Turn on Main Electric Switch and Service
Switch.
(4) Open pilot valve on one side of boiler. Depress
buttononL62GB-3CPilotSafetySwitchto
which it is connected and light pilot with match.
Continue to hold button in for one minute
or until pilot remains lighted after button is
released. Light pilot on opposite side of boiler
using same procedure.
(5)PressresetbuttononeachRA890Frelay.
(6)OpenManualMainShut-offValves–main
burners will light.
Proceed to Paragraph 15- Minimum Input
Adjustments (for diaphragm “Lo-Hi-Lo” or
motorized type gas valves)
SEQUENCE OF OPERATION EO – See Fig. 47
b.NORMALOPERATION–5015Bthru5026B
(1) When the operating control calls for heat,
terminal#6ofeachRA890FProtectorelayis
energized.
(2)AcomponentcheckcircuitineachRA890
Protectorelay is activated which checks the
electronic network of the relay.
(3) Flame rod circuit between each Q179D pilot and
terminal“F”onitsrespectiveRA890Fproves
presenceofameelectronicallyatitsQ179D
pilot.
(4)Terminal#6oneachRA890Fisenergized
supplying power to its respective main gas
valves.
(5) Main gas valves open and main burners are
ignitedbythepilotames.
(6)Whenoperatingcontrolissatised,terminals#6
and#5ontheRA890Frelaysarede-energized,
main gas valves close and main burners are
extinguished.
(7) The Q179D pilots continue to burn.
c. SAFETY SHUTDOWN
(1) SAFETY SWITCH CIRCUIT
If limit control, low water cut-off or any
other electrical safety switch opens, power
to
terminal#6andallotherterminalsonboth
RA890Frelaysisinterrupted.Maingasvalves
are thus de-energized and main gas burners
areimmediatelyextinguished.Standingpilot
amesintheQ179Dpilotswillcontinueto
burn.
(2) PILOT FAILURE
(a) Flame rod supervision of the Q179D pilots
occurs only during the operating cycle (call
for heat) since it is during this period that
thecontrolisenergizingtheRA890Frelays.
If pilot failure occurs during this period
on one of the Q179D pilots, the main gas
valvescontrolledbythatparticularRA890F
willclosein0.8second.TheRA890Fwill
lock-out on safety within 15 seconds. The
burnerscontrolledbytheotherRA890Fwill
continue to burn.
(b) If pilot failure occurs on one of the Q179D
pilots during the “off” cycle of the operating
control,therewillbenoelectronicamerod
supervisionsinceneitherRA890Frelayis
energized during the off cycle. This is due
to the utilization of a thermocouple in each
Q179Dmodiedpilotwhichcontrolsits
own pilot safety switch. This thermocouple
willcoolin45to90secondsde-energizing
the pilot safety switch which interrupts the
circuit between terminal #5 and the gas
valvesandalsoshutsofftheowofgasto
thepilot.Thus100%shut-offisachieved.
If the operating control calls for heat
duringthisperiodtheRA890Frelaywill
immediatelysense“noame”onthepilot
and the relay will lock out on safety within
15 seconds.
Assuming the pilot on the opposite side is
burning, the gas valves on that side will
openandmainamewillbeignitedonthat
side only.
7. EECONTROLSYSTEM–5006Bthru5014B
TheEEControlSystemutilizesanRA890F
ProtectorelayandaQ179CRecticationPilot,which
inadditiontoapilotburnerandrectifyingamerod
amedetectortoprovepilot,includesanignition
electrode for spark ignition of the pilot. A Webster
612-6A7Transformersuppliesthehighvoltagespark
potential.Oncepilotameisproven,ignitionstopsbut
pilotamecontinuesaslongasthereisa“callforheat”
(intermittent electrically ignited pilot).
TheRA890FProtectorelayPrimaryControlisanon-
programming amplifying relay which when used with
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