RM7890, RM7895 100 Vac
17 .
If used, remove the bypass jumpers from the low fuel pres-
sure limit and subbase.
18 .
If a second stage is used, make sure the automatic second
stage fuel valve(s) opened, and check the lightoff as fol-
lows (otherwise proceed to step 19):
a .
Open the manual second stage fuel valve(s).
b .
Restart the system by raising the setpoint of the operat-
ing 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 pulsat-
ing or unsteady readings will require further attention.
21 .
Make sure all readings are within the required ranges be-
fore proceeding.
NOTE: Upon completing these tests, open the master switch
and remove all test jumpers from the subbase termi-
nals, 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 ev-
ery 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 pe-
riod, turn the pilot gas pressure down very slowly, reading
the manometer (or gauge) as the pressure drops. Stop im-
mediately when the FLAME LED goes out. Note the pres-
sure 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 IG-
NITION 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 manual
main fuel valve(s) and one to watch for ignition .
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 burn-
er 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 ligh-
toff 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 volt-
age is approximately 1.25 to 1.50 Vdc.
10 .
When the main burner lights reliably with the pilot at turn-
down, 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 ter-
minals, 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 igni-
tion 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.
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