11
NOVA PLUS Installation & Operation Manual -
POWER FLAME INCORPORATED
DC4 DRAFT CONTROL
ENTER
ESC
®
6.
Disconnect pilot line at inlet to the pilot gas pressure regulator and purge air from the pilot
gas line. Purging of gas lines must be done in accordance with NFPA 54 of the National
Fire Protection Association’s National Fuel Gas Code. After the air is purged from the gas
supply system, close the pilot cock and reconnect the pilot line. Leave the pilot cock
closed.
Figure 6
Air Switch Locations
7.
Install required system measuring devices: a) appropriate flame signal meter to the flame
safeguard control; b) manometer (or 0-10” W.C. gauge) in the pilot test tee port; c) stack
thermometer and O
2
sample line to the breaching; and d) draft gauge to the combustion
chamber test point.
8.
It is strongly recommended that an automatic gas valve bubble leak test be performed in
accordance with the gas valve manufacturer’s instructions on every new installation and
periodically afterwards in order to ensure that the valve is functioning according to the
manufacturer’s specifications. It is also suggested that the test be conducted during a
normal pre-purge burner operation. This test will reveal any problems that relate to
incorrect wiring of the automatic gas valve that could cause premature energizing of the
valve.
9.
Set the air dampers to the low fire position prior to light-off. This position is determined by
first installing a water tube manometer on the mixing spool air pressure tap, then with the
blower motor running adjust the damper position until approximately 0.2” to 0.5” w.c.
(typical low fire air setting) is obtained on the manometer. At this point also confirm that
motor rotation is correct.
Element Switch: Set to actuate at approximately 1" w.c.
under final purge pressure.
Low Fire Interlock Pressure Switch: Set to actuate at
approximately 0.2" to 0.5" w.c. (low fire damper position).
Primary & Secondary Filter Switches: Primary turns on light (Set to actuate at approximately
-0.5" under normal high fire operating condition. Secondary causes lockout: (Set to actuate
at approximately -0.7"w.c under normal operating conditions. Verify acceptable 02 level.
Combustion Air Flow Switch.
16
NOVA PLUS Installation & Operation Manual -
POWER FLAME INCORPORATED
DC4 DRAFT CONTROL
ENTER
ESC
®
Table 3
Acceptable Stable Pilot and/or Main Flame Current Readings
Control
U.V.
Infrared
R7800
1.25-5.0 DC Volts
1.25-5.0 DC Volts
E
MK7
5 min., 10 or greater normal
5 min., 10 or greater normal
110
10 min., 20 or greater normal
10 min., 20 or greater normal
15.
TROUBLE SHOOTING SUGGESTIONS
1.
Burner Fails to Start
A.
Defective On/Off or fuel transfer switch. Replace
B.
Control circuit has an open control contact. Check limits, low water cutoff, proof
of closure switch and others as applicable.
C.
Bad fuse or switch open on in-coming power source. Correct as required.
D.
Motor overloads tripped. Reset and correct cause for trip out.
E.
Flame safeguard control safety switch tripped out. Reset and determine cause
for apparent flame failure.
F.
Loose connections or faulty wiring. Tighten all terminal screws and consult
wiring diagram furnished with the burner.
G.
Flame safeguard control starting circuit blocked due to flame relay being
energized. Possible defective scanner – replace. Possible defective amplifier –
replace. Scanner actually sighting flame due to leaking fuel valve – correct
unwanted flame cause. Defective flame safeguard control – replace.
H.
Defective blower motor. Repair or replace.
I.
LFI air switch open. Verify damper is in the low fire position or reset switch.
2.
Occasional Lockouts For No Apparent Reason
A.
Gas pilot ignition failure. Refer to pilot adjustment section and readjust to make
certain that the ignition is instant and that flame signal readings are stable and
above minimum values. Use a manometer or 0 to 10” W.C. gas pressure gauge
on pilot test tee to make certain that pressure is as recommended.
B.
Gas pilot ignition. Verify that there are no cracks in the porcelain and that
transformer end and electrode end plug in connections are tight.
C.
Loose or broken wires. Check all wire nut connections and tighten all terminal
screw connections in panel and elsewhere as appropriate.
D.
Ensure that when main flame lights, the air flow switch is not so critically set as to
allow occasional momentary opening of the air switch contacts.
29.
If the burner operation is abnormal, refer to Trouble Shooting Suggestions, as well as
trouble shooting information included in the flame safeguard manufacturer’s bulletin
shipped with the burner. It is also strongly suggested that all test procedures outlined in
the flame safeguard control manufacturer’s bulletin be conducted.
30.
Complete the Burner Start Up Information and Test Data sheets on
page 26.
14.
GAS PILOT IGNITION ADJUSTMENT
Excessive gas pressure and insufficient air are the most common causes of pilot ignition failure.
Gas pressure should be read at the test tee on the pilot gas supply pipe with a manometer or 0
– 10” W.C. gauge. Look for stability of gas pressures at all times. Some job conditions or heat
exchangers may require larger air damper openings or different gas pressures than
recommended. For dependable pilot ignition, always use air damper setting to provide the
MOST air and LOWEST pilot gas pressure settings allowable for good pilot signal at all times.
1.
Remove pilot assembly and check for proper orifice size and spark gap. The spark gap
between
the
electrode
and
inside
radius
of
the
gas
pilot
assembly
should
be
1/8”
–
3/32”.
See
Figure
7
.
FIGURE 7
Typical Pilot
2.
Close checking cock (main test cock). Start up burner and flip run/test switch to test.
3.
Observe pilot signal with DC voltmeter or micro-ammeter and reduce pilot gas pressure
to a point where the signal is erratic or reduced substantially from initial reading.
4.
Raise the pilot gas pressure to the point where the signal is again stable. Remove
scanner and use a mirror to view the pilot flame through the scanner pipe (a live flame
from cigarette lighter or butane torch may be needed to keep scanner actuated). Be
sure to get full coverage of scanner pipe by pilot flame.
Release check switch and observe meter as main gas valve opens. If there is a drop in
signal as this happens, increase pilot pressure slightly until signal is steady at all times.
