Honeywell 7800 Series Manual page 35

WARNING
Do not allow fuel to accumulate in the combustion
chamber. If fuel is allowed to enter the chamber for
longer than a few seconds without igniting, an
explosive mixture could result. It is recommended
that you limit the trial for pilot to ten seconds, and
limit the attempt to light the main burner to two
seconds from the time the fuel has reached the
burner nozzle. In any case, do not exceed the
nominal lightoff time specified by the equipment
manufacturer; close the manual fuel shutoff
valve(s) if the flame is not burning at the end of the
specified time.
CAUTION
1. Use extreme care while testing the system. Line
voltage is present on most terminal connections
when power is on.
2. Open the master switch before removing or in-
stalling the RM7838B or Keyboard Display Mod-
ule connector.
3. Make sure all manual fuel shutoff valve(s) are
closed before starting the initial lightoff check
and the Pilot Turndown Tests.
4. Do not put the system in service until you have
satisfactorily completed all applicable tests in
this section and any others required by the equip-
ment manufacturer.
IMPORTANT:
1. If the system fails to perform properly, note the fault
code, fault message, burner/boiler/furnace/oven sta-
tus, and sequence time on display. Refer to Trouble-
shooting or the Service Handbook, form 65-0111.
2. Repeat ALL required Checkout tests after all adjust-
ments are made. ALL tests must be satisfied with the
flame detector(s) in its FINAL position.
EQUIPMENT REQUIRED
Volt-ohmmeter (one megohm/volt minimum sensitivity)
with:
• 0-300 Vac capability.
• 0-10 Vdc capability.
CHECKOUT SUMMARY
• Preliminary inspection—all installations.
• Flame signal measurement—all installations.
• Initial lightoff check for proved pilot—all installations
using a pilot.
• Initial lightoff check for direct spark ignition of oil—
all burners using DSI.
• Pilot turndown test—all installations using a pilot.
• Hot refractory hold-in test—all installations.
• Ignition spark pickup—all installations.
• Response to other ultraviolet sources—all installations.
• Flame signal with hot combustion chamber—all
installations.
• Safety shutdown tests—all installations.
See Figs. 1 and 2 for the location of component parts and
Fig. 23 or Q7800 Specifications for the terminal locations.
PRELIMINARY INSPECTION
Perform the following inspections to avoid common prob-
lems. Make certain that:
1. Wiring connections are correct and all terminal screws
are tight.
2. Flame detector(s) is clean, and installed and positioned
properly. Consult the applicable Instructions.
3. Correct combination of amplifier and flame detector(s)
is used. See Table 2 in the Specifications.
4. Plug-in amplifier and purge card are securely in place.
5. Burner is completely installed and ready to fire with the
fuel lines purged of air; consult equipment manufacturer's
instructions
6. Combustion chamber and flues are clear of fuel and
fuel vapor.
7. Power is connected to the system disconnect switch
(master switch).
8. Lockout is reset (push in reset button) only if the Relay
Module is powered, see Figs. 1 and 2.
9. Run/Test switch is in RUN position.
10. System is in the STANDBY condition (STANDBY
message is viewable in the VFD).
11. All limits and interlocks are reset.
FLAME SIGNAL MEASUREMENT
(TABLE 8 AND FIG. 29)
Measure the flame signal at the appropriate times as de-
fined in the following Checkout tests. Read the flame signal in
volts dc at the flame amplifier test jacks + and - (Com) or at
the Keyboard Display Module (KDM).
1. Use a volt/ohmmeter with a 0 to 10 Vdc capability.
2. Set the volt/ohmmeter to the 0 to 10 Vdc range.
3. Insert the positive (red) volt/ohmmeter probe into the
+ jack of the flame amplifier. Insert the negative (black)
volt/ohmmeter probe into the - (Com) jack of the flame
amplifier.
4. Allow a few seconds for the meter reading to stabilize.
5. With shutter check amplifiers, read the average stable
voltage, disregarding the peaks and valleys caused by the self-
checking operation.
6. The meter reading must be as specified in Table 7, after
all tests are completed and all adjustments made.
As an option, the flame signal can be checked by using
the KDM.
35
RM7838B
CHECKOUT
Checkout
65-0120—1