Honeywell 7800 Series Manual page 39

6. When the PILOT IGN begins, set the Run/Test Switch
to TEST position to stop the sequence. The FLAME LED
will come on when the pilot ignites.
NOTE: If the sequence does not stop, reset the system and
make sure you set the Run/Test Switch to TEST within
the first eight seconds of the PILOT IGN sequence.
IMPORTANT: You have eight seconds or three seconds,
depending on PFEP selected, to position the Run/Test
Switch to the TEST position to stop the sequence after
the start of the PILOT IGN period.
7. Turn the pilot pressure down very slowly, reading the
manometer (or pressure gauge) as it drops. Stop instantly
when the FLAME LED goes out. Note the pressure at the
RM7800 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 or the flame
signal increases to 1.25 Vdc.
NOTE: If there is no flame for fifteen seconds with the
sequence stopped at this point, the RM7800 will lockout
and flash a lockout message, see Fig. 34.
Fig. 34—Flame-out timer lockout.
LOCKOUT #16 PFEP
* Flame-out Timer*
Condition at the
time of lockout . . .
PILOT HOLD:
(Run/Test Sw)
8. Repeat step 7 to verify the pilot gas pressure reading at
the exact point the FLAME LED light goes out.
9. 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.
10. Set the Run/Test Switch in the RUN position 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 18.
NOTE: This step requires two people, one to open the manual
valve(s) and one to watch for ignition.
11. If the main burner flame is not established within five
seconds, or within the normal lightoff time specified by the
equipment manufacturer, close the manual main fuel shutoff
valve(s) and open the master switch. If the lightoff was rough,
the pilot flame size is too small.
12. Recycle the burner and stop the sequence in the PILOT
IGN period by using the Run/Test Switch.
13. Increase the pilot flame size by increasing its fuel flow
until a smooth main flame is accomplished.
14. Reposition the flame scanner sight tube or use ori-
fices until the pilot flame signal voltage is in the range of
1.25 - 1.50 Vdc.
15. 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 that recommended by the
equipment manufacturer.
16. If used, remove the bypass jumpers from the subbase
terminals, limits/controls, or switches.
17. Run the system through another cycle to check for
normal operation.
18. 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 in-
creases 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.
M5001
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:
4. Make sure the leadwires from the flame rod and
ignition electrode are not too close together.
5. Replace any deteriorated leadwires.
6. If the problem cannot be eliminated, the system may
have to be changed to an ultraviolet flame detection system.
39
a. 6000V systems—1/16 to 3/32 in. (1.6 to 2.4 mm).
b. 10,000V systems—1/8 in. (3.2 mm).
RM7800E,G,L,M
CHECKOUT
65-0117—2