Product Overview

RM7890; RM7895 100 VAC 7800 SERIES RELAY MODULES
23 66-1195—01
a. Open the manual second stage fuel valve(s).
b. Restart the system by raising the setpoint of the
operating controller.
c. When the first stage burner flame is established,
watch for the automatic second stage fuel valve(s)
top open. Observe that the second stage lights off
properly.
d. Make burner adjustments for flame stability and
input rating.
e. Shut down the system by lowering the setpoint of
the operating controller. Make sure the burner flame
goes out and that all automatic fuel valve(s) close.
19. Restart the system by closing the burner switch and/or
raising the setpoint of the operating controller. Observe
that the burner flame is established during PILOT IGN,
within the normal lightoff time specified by the
equipment manufacturer.
20. Measure the flame signal. Continue to check for the
proper signal, see Table 10, through the RUN period.
Any pulsating or unsteady readings will require further
attention.
21. Make sure all readings are within the required ranges
before proceeding.
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. If using AMPLI-CHECK™ and
one megohm per volt meter, the flame signal will fluctuate
every time the amplifier does a self 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 by raising the setpoint of the operating
controller. The primary sequence should start and
PILOT IGNITION for the RM7890 (PREPURGE for the
RM7895) should begin.
6. After the sequence has entered the normal burner run
period, turn the pilot gas pressure down very slowly,
reading the manometer (or gauge) as the pressure
drops. Stop immediately when the FLAME LED goes
out. Note the pressure at this point.
NOTE: If there is no flame present for the selected Flame
Failure Response Test (FFRT), the relay module
will lock out.
a. If the Flame Failure Action jumper (see Table 6 or 7,
JR2) is not clipped: allow the RM7890 to recycle to
PILOT IGNITION or the RM7895 to recycle through
PREPURGE. If the Flame Failure Action jumper is
clipped: push the reset pushbutton and allow the
RM7890D to recycle to PILOT IGNITION or the
RM7895E,F to recycle through PREPURGE.
b. As the control attempts to relight the pilot, 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 approximately
1.25 Vdc. This step must be completed within 4 or
10 seconds, depending on the selected PFEP, or
lockout occurs.
c. Turn the pilot back down slightly but not enough to
cause the FLAME LED to go out. (Keep the pilot gas
pressure just above the reading noted in step 6
above.)
NOTE: Step d requires two people, one to open the man-
ual main fuel valve(s) and one to watch for igni-
tion.
d. With the sequence in the normal burner run mode,
make sure the automatic fuel valve(s) is open.
Smoothly open the manual main fuel shutoff
valve(s) and watch for main burner lightoff.
e. If the main flame is not established within five
seconds or the normal lightoff period specified by
the burner manufacturer, close the manual main fuel
shutoff valve(s) and open the master switch. Then
return to step 6a. If the burner flame is established
in the normal lightoff period, proceed to step 10.
7. Recycle the burner and let the sequence advance to the
PILOT IGN period for the RM7890; advance to the PRE-
PURGE period for the RM7895.
8. Increase the pilot flame size by increasing its fuel flow
until a smooth main flame is accomplished.
9. Reposition the flame rod until the pilot flame signal
voltage is approximately 1.25 to 1.50 Vdc.
10. When the main burner lights reliably with the pilot at
turndown, disconnect the manometer (or pressure
gauge) and turn up the pilot gas flow to the level
recommended by the equipment manufacturer.
11. If used, remove the bypass jumpers from the subbase
terminals, limits/control or switches.
12. Run the system through another cycle to check for
normal operation.
13. Return the system to normal operation.
Ignition Interference Test (All Flame
Rods)
Test to be sure 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 causes a safety shutdown. If it increases the flame
signal, it can 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 0.5 Vdc) indicates ignition interference.