Burnham MST288, Installation, Operating And Service Instructions

Page: 54 / 68

54
A. COMBUSTION
1. NOZZLES — Although the nozzle is a relatively
inexpensive device, its function is critical to the
successful operation of the oil burner. The selection
of the nozzle supplied with the MegaSteam™ boiler
is the result of extensive testing to obtain the best
flame shape and efficient combustion. Other brands
of the same spray angle and spray pattern may be
used but may not perform at the expected level of
CO
2
and smoke. Nozzles are delicate and should be
protected from dirt and abuse. Nozzles are mass-
produced and can vary from sample to sample. For
all of those reasons a spare nozzle is a desirable item
for a serviceman to have.
2. FLAME SHAPE — Looking into the combustion
chamber through the observation port, the flame
should appear straight with no sparklers rolling up
toward the crown of the chamber. If the flame drags
to the right or left, sends sparklers upward or makes
wet spots on the chamber walls, the nozzle should
be replaced. If the condition persists look for fuel
leaks, air leaks, water or dirt in the fuel as described
above.
3. FUEL LEAKS — Any fuel leak between the
pump and the nozzle will be detrimental to good
combustion results. Look for wet surfaces in the air
tube, under the ignitor, and around the air inlet. Any
such leaks should be repaired as they may cause
erratic burning of the fuel and in the extreme case
may become a fire hazard.
4. AIR LEAKS — Any such leaks should be repaired,
as they may cause erratic burning of the fuel and in
extreme cases may become a fire hazard.
5. GASKET LEAKS — If 11.5 to 12.5% CO
2
with a
#1 smoke cannot be obtained in the breeching, look
for air leaks around the burner mounting gasket,
observation door, and canopy gasket. Such air leaks
will cause a lower CO
2
reading in the breeching. The
smaller the firing rate the greater effect an air leak
can have on CO
2
readings.
6. DIRT — A fuel filter is a good investment.
Accidental accumulation of dirt in the fuel system
can clog the nozzle or nozzle strainer and produce a
poor spray pattern from the nozzle. The smaller the
firing rate, the smaller the slots become in the nozzle
and the more prone to plugging it becomes with the
same amount of dirt.
7. WATER — Water in the fuel in large amounts will
stall the fuel pump. Water in the fuel in smaller
amounts will cause excessive wear on the pump,
but more importantly water doesn’t burn. It chills
the flame and causes smoke and unburned fuel to
pass out of the combustion chamber and clog the
flueways of the boiler.
SECTION xI: TROUBLE SHOOTING
8. COLD OIL — If the oil temperature approaching
the fuel pump is 40°F or lower, poor combustion or
delayed ignition may result. Cold oil is harder to
atomize at the nozzle. Thus, the spray droplets get
larger and the flame shape gets longer. An outside
fuel tank that is above grade or has fuel lines in a
shallow bury is a good candidate for cold oil. The
best solution is to bury the tank and lines deep
enough to keep the oil above 40°F.
9. HIGH ALTITUDE INSTALLATIONS — Air
openings must be increased at higher altitudes. Use
instruments and set for 11.5 to 12.5% CO
2
.
10. START-UP NOISE — Late ignition is the cause
of start-up noises. If it occurs recheck for electrode
settings, flame shape, air or water in the fuel lines.
11. SHUT DOWN NOISE — If the flame runs out of
air before it runs out of fuel, an after burn with noise
may occur. That may be the result of a faulty cut-off
valve in the fuel pump, or it may be air trapped in the
nozzle line. It may take several firing cycles for that
air to be fully vented through the nozzle. Water in the
fuel or poor flame shape can also cause shut down
noises.
NOTICE
CHECK TEST PROCEDURE. A very good test for
isolating fuel side problems is to disconnect the
fuel system and with a 24" length of tubing, fire
out of an auxiliary five gallon pail of clean, fresh,
warm # oil from another source. If the burner runs
successfully when drawing out of the auxiliary
pail then the problem is isolated to the fuel or fuel
lines being used on the jobsite.
B. OIL PRIMARY CONTROL
1. Burner (control) will not come on.
a. No power to control.
b. Control is in lockout or restricted mode. Press
reset button for one (1) second to exit lockout. If
control has recycled three times within the same
call for heat, it will enter into restricted mode.
To reset from restricted mode, refer to Section
VIII, Paragraph I, No. 2 for details.
c. CAD cell seeing light.
d. CAD assembly defective.
e. Control motor relay is stuck closed (see note
below).
2. Burner (control) will light, then shut down after a
short time, then restart after one (1) minute.
a. CAD cell is defective.
b. Air leaking into oil line causing flame out.
c. Defective nozzle causing flame to be erratic.