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Figure 9. Typical wiring using Model RM7897A (for reference only)
AiR
PROVING
SWITCH
FLAME ROD
SEE NOTE I
LINE VOLTAGE
SE3VICE
t20V 60Hz
_
FROM FUSED DISCONNECT
SUPPLIED
BY INSTALLER
HIGH GAS
LOW GAS
._.k
PRESSURE
PRESSURE
LW.C.O.
HIGH
OPERATING
LIMIT
CONTROL
w m m W_RED BY _NS'TALLER
_*
SUPPLiEDBY
CUSTOMER
FIBLD WiRiNG TIE.- N
Key:
TRANS
o _GN_T!ON
T_AINSFORMER
GV1 _ ©N_'@FFGAS VALVE
GV2 _ HIGH LOW VALVE
LWC©.
- LOW WATER CU%OP_
WkeColor:
A-, WH{TE
B BLACK
C _ BLUE
D _ ORANGE
E _BROWNfRED
G -BROWN
H - REDfWHt_
E
L _ B_CKfRED
Notes:
. FOR UV RUN WHTE W!RE TO G TER#,.t_NAL
AND BLUE W_RE TO F TERM NAL
FOR FLAME ROD RUN W_RE TO F, G
iS A CHASSIS GROUND,
2, "- CLiP AND RB'_,IOVE JUMPER JR1
G_O
TERM_N_AL
Sequence
of
peration
..
(typical for RM7895A
flame safeguard
primary control)
1. Initiate
- The primary control enters the INITI-
5.
ATE sequence when the control is first powered
on or power returns after an interruption.
The
initiate sequence is a ten second delay during
which the control verifies line voltage stability.
.
.
.
Standby
- The control enters STANDBY until
the limits, operating limit control, burner switch,
and all microcomputer-monitored
circuits are in
the correct state.
Load demand - Operating limit control contacts
close on drop in temperature
(or pressure) and
initiates the start sequence.
Prepurge
- The control will signal the PRE-
PURGE sequence
when the airflow interlock
and all switches are in the correct state. The Pre-
purge sequence is the amount of time the blower
motor runs prior to the ignition start sequence.
Timing for the Prepurge sequence is determined
by a card mounted inside the control module
(typically 30 seconds).
Trial for ignition (TFI) - After the Prepurge se-
quence has timed out, the ignition and main gas
valves will be energized.
Because the burner
has direct spark ignition for the main flame, the
flame must be established and detected by the
control within 4 seconds or lockout will occur.
.
Run - With a flame established and the control
continuing to detect a flame, the burner will op-
erate in the RUN mode until the load demand is
satisfied or a limit opens.
7. Load Satisfied
-The
burner switches to idle un-
til the next call for operation.
j
NOTICE
]
This operation
sequence
is typical
and for reference
only. The primary control could vary, depending on the
customer specification and code requirements.
For the
specific operating sequence that applies to your instal-
lation, consult the appliance manufacturer's
directions,
wiring instructions, and control manufacturer's
literature
supplied with your burner.
112
6104
BCGIO
RoB
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