Honeywell 7800 Series Installation Instructions Manual page 22

RM7890, RM7895 100 Vac
8 . When the pilot ignites, measure the flame signal. If the
pilot flame signal is unsteady or approaching the 1.25
Vdc minimum value, adjust the pilot flame size or detector
position to provide a maximum and steady flame signal.
9 . Recycle the system to recheck lightoff and pilot flame
signal.
10 . When the RUN period (MAIN IGN period for the RM7895)
is displayed by the MAIN LED, make sure the automatic
main fuel valve is open; then smoothly open the manual
main fuel shutoff valve(s) and watch for main burner
flame ignition. When the main burner flame is established,
p roceed to step 17.
11 . If the main burner flame is not established within five
seconds or the normal lightoff time specified by the equip-
ment manufacturer, close the manual main fuel shutoff
valve(s).
12 . Recycle the system to recheck lightoff and pilot flame sig-
nal.
13 . Let the relay module recycle to the RUN period (MAIN IGN
period for the R7895). Smoothly open the manual fuel
shutoff valve(s) and try lightoff again. (The first attempt
may have been required to purge the lines and bring suffi-
cient fuel to the burner.)
14 . If the main burner flame is not established within five
seconds or the normal lightoff time specified by the
equipment manufacturer, close the manual fuel shutoff
valve(s). Check all burner adjustments.
15 . If the main burner flame is not established after two
attempts:
a . Check for improper pilot size.
b . Check for excess combustion air.
c . Check for adequate fuel flow.
d . Check for proper gas supply pressure.
e . Check for proper valve operation.
f . Check for proper pilot flame positioning.
16 . Repeat steps 11 through 15 to establish the main burner
flame, then proceed to step 17.
17 . With the sequence in RUN, make burner adjustments for
flame stability and BTU input rating.
18 . Shut down the system by opening the burner switch or by
lowering the setpoint of the operating controller. Make
sure the main flame goes out. There may be a delay due
to gas trapped between the valve(s) and the burner. Make
sure 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 pilot is established during PILOT IGN and the
main burner flame is established during RUN (MAIN IGN
for RM7895) within the normal lightoff time.
20 . Measure the flame signal. Continue to check for the proper
signal, see Table 10, through the RUN period.
21 . Run the burner through another sequence, observing the
flame signal for:
a . Pilot flame alone (unless using direct spark ignition).
b . Pilot and main flame together. Also observe the time it
takes to light the main flame. Ignition of the main flame
should be smooth.
22 . Return the system to normal operation.
23 . Make sure all readings are in the required ranges before
proceeding.
32-00216-01
NOTE: Upon completing these tests, open the master switch
and remove all test jumpers from the subbase termi-
nals, limits/controls or switches .
Initial Lightoff Check for Direct Spark
Ignition (DSI)
Use this check for gas and oil burners that do not use a pilot
immediately following the preliminary inspection. Refer to the
appropriate sample block diagram of field wiring for the igni-
tion transformer and fuel valve(s) hookup.
NOTE: Low fuel pressure limits, if used, could be open; if so,
bypass them with jumpers during this check .
1 . Open the master switch.
2 . Complete the normal checkout of the fuel supply and
equipment as recommended by the equipment manufac-
turer.
3 . Close all manual main fuel shutoff valve(s). Check that the
automatic fuel valve(s) are closed. Make sure fuel is not
entering the combustion chamber.
4 . Close the master switch and start the system with a call for
heat by raising the setpoint of the operating controller; see
Fig. 15 or the relay module operating sequences. The pri-
mary sequence should start with the 10-second INITIATE
sequence.
5 . Let the sequence advance through STANDBY and SAFE-
START CHECK for the RM7890 (PREPURGE for the
RM7895) to Ignition Trial. Ignition spark should occur.
Listen for the click of the first stage fuel solenoid valve(s).
6 . Let the program sequence complete its cycle.
7 . Open the manual fuel shutoff valve(s).
8 . Push the reset button and recycle the program sequence
through STANDBY and SAFE-START CHECK for the
RM7890 (PREPURGE for the RM7895).
9 . Watch for the FLAME LED to help determine when the first
stage burner flame is established. If it is established, go to
step 15.
10 . 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.
11 . Check all burner adjustments.
12 . Wait about three minutes. Close the master switch, open
the manual fuel shutoff valve(s), and try again to light off
the burner. The first attempt may have been required to
purge the lines and bring sufficient fuel to the burner.
13 . 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.
14 . If necessary, repeat steps 8 through 13 to establish the
first stage burner flame. Then proceed to step 15.
15 . When the first stage burner flame is established, the se-
quence will advance to RUN. Make burner adjustments for
flame stability and input rating. If a second stage is used,
proceed to step 18.
16 . Shut down the system by opening the burner switch or by
lowering the setpoint of the operating controller. Make
sure the burner flame goes out and make sure all automat-
ic fuel valves close.
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