Modine Manufacturing POR Installation And Service Manual page 15

service instructions
The best adjusted flame pattern will be a clean, yellow,
solid cone which is well established on the burner head and
terminates into short licks of flame within the ceramic fiber
fire pot.
An accurate combustion check can only be made with the
proper instrumentation as described below.
A. Install a pressure gauge on the pressure gauge port of the
fuel unit. Start burner and adjust oil pressure to 130 +/- 2psi
for POR100 and 145, 100 +/- 2psi for POR 185. See Item 6
- Initial Start-Up.
B. Make two holes about 1/4 inch in diameter in the flue
pipe about 6 inches above the flue connection but below
barometric draft control. Two openings permit taking the
stack temperature in one, while the second opening is used
to conduct draft test, and carbon dioxide (CO 2 ) test. Close
openings with sheet metal screws after tests have been
completed.
C. Insert stem of stack thermometer in one opening while
performing other tests.
D. Allow burner to operate approximately 5 minutes before
taking any readings. To measure draft, place draft gauge
on any level surface adjacent to the unit heater and adjust
it to zero. Draft gauge should read minus 0.02 inches W.C.
minimum. Draft can be changed by adjusting the weight
on the barometric draft control. Improper draft can cause
erratic and incomplete combustion which will result in noisy
operation, soot deposits, excessive smoke and fuel oil
odors.
E. The smoke tester measures smoke content of flue gas
and is prepared by inserting a strip of clean filter paper in
the slot provided. Insert probe into flue and pump smoke
tester ten strokes to draw a sample of flue gas through the
filter paper. Filter paper should be removed and compared
against the standard Bacharach smoke scale which has
ten graded color spots from white (O smoke) to the darkest
shade of gray. To adjust the combustion air, loosen the
locknut for the combustion air bands on the side of the
burner and rotate the bands slightly until a #0 to #1 smoke
reading is achieved. Increasing the air opening will lighten
the smoke spot and decreasing the air openings will darken
it. Tighten locknut and recheck reading.
F. Test the flue gas for carbon dioxide (CO 2 ) content. Zero
the CO 2 analyzer and insert probe into flue pipe and draw
sample of the flue gas into analyzer. The concentration of
CO 2 should be 11.5 to 12.5%. CO2 levels above 12.5% are
not recommended as sooting could occur as conditions and
fuel vary at zero smoke.
G. Conclude testing by reading stack temperature and subtract
room temperature to get the net stack temperature. Using
this figure and the CO 2 reading, use the slide calculator
provided with the CO 2 analyzer to compute steady-state
efficiency. Efficiencies of 80% should be attainable.
Primary control service
The primary control (see Figure 12.2) is not intended to be
serviced in the field. Replace defective controls. It senses
ignition failure and flame failure and can be checked by a
relatively simple procedure. Start the unit.
a. Simulate flame failure by removing one cad cell lead from
the F terminal of primary control with burner on. Fifteen
seconds after flame extinguishes, primary control will lock
out and stop burner motor and ignition spark. Attach the
cad cell lead to the F terminal. Reset safety switch on top of
primary control after test.
Do not reset primary control if heat exchanger is hot. Wait
until cooled. If unit fails to operate properly after resetting
twice, consult the factory.
If operation is not as described and wiring is in accordance with
diagram on page 6, refer to cad cell service before replacing
primary control.
cad cell service
Under normal operating conditions the cad cell does not require
cleaning. Small accumulations on the surface of the cell will
not affect its operation. However, if a badly adjusted burner
has caused heavy accumulation of soot, the surface should be
wiped carefully to remove all opaque substances and restore
full view of the oil flame.
If cad cell should ever be damaged, the cell may be removed by
simply unplugging it from the socket assembly. Avoid disturbing
the positioning of the socket assembly. Replace the damaged
cell.
figure 15.1
cad cell
fuel unit service
A Beckett two stage, 3450 RPM fuel unit is supplied on all
Modine oil unit heaters. Two stage fuel units are intended
for high lift applications, up to 15 inches Hg. (Mercury) of
inlet vacuum or the equivalent of 20 feet of vertical lift. It is
recommended that they be used with a two pipe oil supply
system and they are shipped with the bypass plug installed for
such applications.
4-522.4
CAUTION
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