Honeywell 7800 Series Installation Instructions Manual page 36

RM7888A 7800 SERIES RELAY MODULE
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 auto-
matic 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 manufacturer. Cycle system by
energizing the appropriate special 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.
NOTE: Upon completing these tests, open the master
switch and remove all test jumpers from the sub-
base terminals, limits/controls or switches.
22. Return the system to normal operation.
Pilot Turndown Test (All Installation
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 1 Megohm/volt meter, the flame
signal will fluctuate every time the amplifier does a
selfcheck 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 mea-
sure 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
(terminals 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.
32-00214—01
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.
9. Energize the appropriate special function input (ter-
minal 17, 19, or 20) and let the sequence proceed. At
ten seconds into the Ignition Trial period, make sure
the automatic main fuel valve(s) open; then
smoothly open the manual main fuel shutoff valve(s)
(or any other manually opened safety shutoff
valve(s), if used) and watch for main burner ignition.
If the main burner flame is established, proceed to
step 14.
NOTE: This step requires two people, one to open the
manual valve(s) and one to watch for ignition.
10. If the main burner flame is not established within
five seconds, or within the normal lightoff time spec-
ified by the equipment manufacturer, close the man-
ual main fuel shutoff valve(s) and open the master
switch. If the lightoff was rough, the pilot flame size
is too small.
11. Recycle the burner and stop the sequence in PILOT
IGN period.
12. Increase the pilot flame size by increasing its fuel
flow until a smooth main flame is accomplished.
13. Reposition the flame scanner sight tube or use ori-
fices until the pilot flame signal voltage is in the
range of 1.25 to 1.50 Vdc.
14. When the main burner lights reliably with the pilot at
turndown, disconnect the manometer (or pressure
gauge) and turn the pilot gas flow up to the recom-
mendation of the equipment manufacturer.
15. If used, remove the bypass jumpers from the sub-
base terminals, limits/controls or switches.
16. Run the system through another cycle to check for
normal operation.
17. Return the system to normal operation.
Ignition Interference Test (All
Flame Rods)
Test to make certain that a false signal from a spark
ignition system is not superimposed on the flame signal.
Ignition interference can subtract from (decrease) or add
to (increase) the flame signal. If it decreases the flame
signal enough, it will cause a safety shutdown. If it
increases the flame signal, it could cause the FLAME LED
to come on when the true flame signal is below the
minimum acceptable value.
Start the burner and measure the flame signal with both
ignition and pilot (or main burner) on, and then with only
the pilot (or main burner) on. Any significant difference
(greater than .5 Vdc) indicates ignition interference.
To Eliminate Ignition Interference
1. Make sure there is enough ground area.
2. Be sure the ignition electrode and the flame rod are
on opposite sides of the ground area.
3. Check for correct spacing on the ignition electrode:
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