Honeywell 7800 Series Manual page 40

RM7888A
CHECKOUT
4. Verify that the combustion chamber has been prop-
erly purged.
5. Close the master switch and start the system by
energizing terminal 6 (Special Function 1). See RM7888A
Sequence of Operation. The program should start the ten
second INITIATE sequence.
6. Ignition spark should occur. Listen for the click of the
first stage fuel solenoid valve(s).
7. Let the program sequence complete its cycle.
8. Open the manual fuel shutoff valve(s).
9. Push the reset pushbutton and recycle the program.
10. Watch for the FLAME LED to help determine when
the first stage burner flame is established. If it is established,
proceed to step 16.
11. If the first stage burner flame is not established within
four seconds, or within the normal lightoff time specified by
the equipment manufacturer, close the manual fuel shutoff
valve(s), and open the master switch.
12. Check all burner adjustments.
13 Wait about three minutes. Close the master switch,
open the manual fuel shutoff valve(s), and try to lightoff the
burner again. The first attempt may have been required to
purge the lines and bring sufficient fuel to the burner.
14. If the first stage burner flame is not established within
four seconds, or within the normal lightoff time specified by
the equipment manufacturer, close the manual fuel shutoff
valve(s) and open the master switch.
15. If necessary, repeat steps 12 through 14 to establish
the first stage burner flame after verifying that the system
has been properly purged. Then proceed to step 16.
16. When the first stage burner flame is established, the
sequence will advance when the appropriate special func-
tion input (terminal 17, 19, or 20) is energized. See RM7888A
Sequence of Operation. Make burner adjustments for flame
stability and input rating.
17. Shut down the system by opening the burner switch
or by de-energizing terminal 6 (Special Function 1). Make
sure the burner flame goes out and all automatic fuel valves
close.
18. If used, remove the bypass jumpers from the low fuel
pressure limit and subbase.
19. Restart the system by closing the burner switch and/
or energizing special function 1 (terminal 6). Observe that
the burner flame is established during PILOT IGN, within
the normal lightoff time specified by the equipment manu-
facturer. Cycle system by energizing the appropriate spe-
cial function input. See RM7888A Sequence of Operation.
20. Measure the flame signal. Continue to check for the
proper signal, see Table 11, through the RUN period. Check
the signal at both High and Low firing rate positions and
while modulating. Any pulsating or unsteady readings will
require further attention.
21. Make sure all readings are in the required ranges
before proceeding.
65-0175
NOTE: Upon completing these tests, open the master switch
and remove all test jumpers from the subbase terminals,
limits/controls or switches.
22. Return the system to normal operation.
PILOT TURNDOWN TEST
(ALL INSTALLATIONS USING A PILOT)
Perform this check on all installations that use a pilot.
The purpose of this test is to verify that the main burner can
be lit by the smallest pilot flame that will hold in the flame
amplifier and energize the FLAME LED. Clean the flame
detector(s) to make sure that it will detect the smallest
acceptable pilot flame. If using Ampli-check™ or Self-
Checking Amplifier and 20 kohm/volt meter, the flame
signal will fluctuate every time the amplifier does a self-
check or a shutter check.
NOTE: Low fuel pressure limits, if used, could be open. If
so, bypass them with jumpers during this test.
1. Open the master switch.
2. Close the manual main fuel shutoff valve(s).
3. Connect a manometer (or pressure gauge) to measure
pilot gas pressure during the turndown test.
4. Open the manual pilot shutoff valve(s).
5. Close the master switch and start the system with a
call for heat. (Energize terminal. 6 [Special Function 1].)
The program sequence should start.
NOTE: If the sequence does not stop, reset or restart the
system and make sure the special function inputs (termi-
nals 17, 19 and 20) are in the proper state. See RM7888A
Sequence of Operation..
6. Very slowly turn the pilot pressure down, reading the
manometer (or pressure gauge) as it drops. Stop instantly
when the FLAME LED goes out. Note the pressure at the
RM7888A flame relay dropout point. The pilot is at the
minimum turndown position. Immediately turn up the pilot
pressure until the FLAME LED comes on again.
NOTE: If there is no flame for a period of time exceeding
the flame failure response time [FFRT] of the amplifier,
the RM7888A will lockout.
7. Repeat step 6 to verify the pilot gas pressure reading
at the exact point the FLAME LED light goes out.
8. Increase the pilot pressure immediately until the
FLAME LED comes on, and then turn it down slowly to
obtain a pressure reading just above the dropout point or
until the flame signal increases to 1.25 Vdc.
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