Honeywell RA890G, Manual

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5 60-2035—9
RA890G
INSTALLATION • OPERATION AND CHECKOUT
Fig. 3—Oil-Fired system with interrupted
ignition.
The use of manual reset limits is desirable with the
RA890G to prevent the system from cycling off the high
limit and to assure that the condition that causes the limita-
tion is detected as soon as possible.
MOUNT RA890G
Check that the power is Off.
Remove relay cover and position the RA890G over the
Q270A Universal Mounting Base. See Fig. 4. Start all ten
mounting screws and tighten uniformly. These screws com-
plete electrical circuits and hold the RA890G to the subbase.
As shipped from the factory, the RA890G is suitable for
use with interrupted or intermittent systems.
Fig. 4—RA890G and Q270A Subbase.
TERMINAL
BLOCKS
RA890G
BASE
FLAME
CURRENT
TEST JACK
RA890G
COVER
THUMBSCREW
RESET
PUSHBUTTON
LOAD
RELAY (1K)
Q270A
UNIVERSAL
SUBBASE
M8720
TRANSFORMER TR2
TRANSFORMER TR1
FLAME
RELAY (2K)
SAFETY
SWITCH
M8719
L1
(HOT)
L2
1
2
3
4
3
2
4
4
1
FOR INTERMITTENT IGNITION,
CONNECT TO TERMINAL 3.
ALARM TERMINALS OPTIONAL.
PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
MAY USE LINE OR LOW VOLTAGE CONTROLLER. IF LINE VOLTAGE
CONTROLLER IS USED, CONNECT IT BETWEEN THE LIMIT CONTROL
AND TERMINAL 6. JUMPER T-T.
LINE VOLTAGE
CONTROLLER
IGNITION
TRANSFORMER
PILOT
GAS VALVE
LOW VOLTAGE
CONTROLLER
BLUE
WHITE
6
T
T
F
G 2
2
1
3
4
5
DISCONNECT
SWITCH
POWER
SUPPLY
RA890G
MANUAL OR AUTO RESET
LOCKOUT LIMIT CONTROL
SECOND STAGE
OIL VALVE
(IF USED)
OIL
VALVE
Operation And Checkout
CAUTION
1. Use extreme care while testing the RA890G;
line voltage is present on some terminals and
contacts when power is On.
2. Disconnect power supply before removing
cover, removing RA890G from subbase, or
reinstalling RA890G onto subbase.
PRELIMINARY CHECKS
Before placing the system in operation, complete the
following preliminary checks:
1. Check wiring. Use a meter to check the continuity of
all circuits.
2. Check flame detector installation.
3. Check burner adjustments.
4. Thoroughly purge gas piping.
5. Reset the safety switch by pushing in and then releas-
ing the purple safety switch button.
NORMAL OPERATION SUMMARY
Refer to Fig. 5 for the internal schematic of the control.
1. Call for heat—Load relay pulls in after a slight delay
(flame relay must be out), ignition starts, pilot valve or
burner motor is powered. Safety switch heats. A safety
shutdown occurs if a flame or flame simulating condition is
detected at startup.
2. Flame proved—Flame relay pulls in, safety switch
heater is de-energized, main valve is powered, ignition is cut
off (if used for interrupted ignition).
3. Call for heat satisfied—Load relay drops out, fuel
valves close, burner motor stops, and flame relay drops out.
NOTE: The pull-in of the load relay is delayed by a ther-
mistor with a nominal delay time of 3 to 5 seconds. The
thermistor is affected by ambient temperature. The delay
time may be as little as two seconds when the ambient
temperature is high, or as long as 30 seconds when the
ambient temperature is low. As the thermistor warms up,
the 1K relay may hum slightly before it pulls in. This is
normal.