Product Overview

55
103859-12 - 8/19
MPO-IQ
Installation & Service Manual
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 MPO-IQ 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.
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 locate the tank near the boiler in
the basement utility room or bury the tank and lines
deep enough to keep the oil above 40°F. Check
environmental issues with local authorities having
jurisdiction.
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 #2 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 (Oil Primary)
1. Burner (Oil Primary) will not come on.
a. No power to Oil Primary.
b. Oil Primary 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 J, 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.
12 Troubleshooting