U.S. Boiler Company MPO-IQ Service manual

103859-07 - 8/15 Price - $5.00
9700609
INSTALLATION, OPERATING AND
SERVICE INSTRUCTIONS FOR
MPO -IQ™
3-PASS OIL BOILER
For service or repairs to boiler, call your heating contractor. When seeking information on boiler, provide
Boiler Model Number and Serial Number as shown on Rating Label.
Boiler Model Number
MPO - IQ
Boiler Serial Number Installation Date
Heating Contractor Phone Number
Address
As an ENERGY STAR®Partner, U.S. Boiler Company has determined that the MPO-IQ™ boiler meets the ENERGY STAR®
guidelines for energy efciency established by the United States Environmental Protection Agency (EPA).

61
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 ame shape and efcient
combustion. Other brands of the same spray angle and
spray pattern may be used but may not perform at the
expected level of CO2and 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 ame should
appear straight with no sparklers rolling up toward the
crown of the chamber. If the ame 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 re 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 re hazard.
5. GASKET LEAKS — If 11.5 to 12.5% CO2with 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
CO2 reading in the breeching. The smaller the ring rate
the greater effect an air leak can have on CO2readings.
6. DIRT — A fuel lter 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 ring 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 ame and causes smoke
and unburned fuel to pass out of the combustion chamber
and clog the ueways 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
ame shape gets longer. An outside fuel tank that is
XIII. TROUBLE SHOOTING
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—Airopenings
must be increased at higher altitudes. Use instruments
and set for 11.5 to 12.5% CO2.
10. START-UP NOISE — Late ignition is the cause of
start-up noises. If it occurs recheck for electrode settings,
ame shape, air or water in the fuel lines.
11. SHUT DOWN NOISE — If the ame 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 ring cycles for that air to be fully
vented through the nozzle. Water in the fuel or poor ame
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, re
out of an auxiliary ve 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 XI,
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 ame out.
c. Defective nozzle causing ame to be erratic.
d. Excessive airow or draft causing ame to leave
burner head.
e. Excessive back pressure causing ame to be erratic.

62
XIII. TROUBLE SHOOTING (continued)
Possible ERR (Boiler Control Error) Values:
Err
Value Description
1Temperature Sensor Fault
2Communications Fault
3Internal Hardware Fault
4Burner Output (B1) Fault
5Line Voltage Fault (< 80 Vac)
6Fuse Missing
7User Setting Lost, (reset to factory defaults)
8Manual Reset Lockout (resettable)
Possible STA (status) Values:
sTa
Value Description
1Standby
4Pre-purge
6Trial for Ignition
7Carryover
8Running
9Post-Purge
10 Retry/Recycle Display
14 Hard Lockout
15 Waiting for Limit to Close
16 Flame Present Out of Sequence
17 Self Test
StA Status (see Status Numbers)
bt Boiler Temperature
SP Operating Setpoint (Outdoor Reset)
HL High Limit Setpoint
HdF High Limit Differential
hr Heat Request Status
dh DHW Heat Request Status
CAD Cad Cell Resistance (ohms)
run Run Time Hours
CYC Boiler Cycles
Err Error (see Error Numbers)
Erp External Device Error (see Error Numbers)
Operating Mode Parameters Press “I” key on the control to
change from one parameter to the
next. Each setting will alternate
between display code (for
example STA) and value.
Figure 36: Boiler Control
User Interface
3. Control locks out after Trial For Ignition (TFI).
a. No oil to burner.
b. Shorted electrodes.
c. Nozzle clogged.
d. Airow too high.
e. Ignitor module defective.
f. CAD cell defective.
g. Oil valve stuck open or closed.
Note: The Safety Monitoring Circuit (SMC) is
designed to provide lockout in the event of a
stuck or welded motor relay.
C. IQ OIL BOILER CONTROL
When a problem occurs with the boiler operation, the IQ
Control System easily provides specic, valuable information
to help resolve the issue quickly. The display on the Boiler
Control should be the rst place to check, see Figure 36.
1. Error Code "Err" IS NOT displayed on the Boiler
Control: This is one of two conditions that occur when
a problem arises. In this circumstance, the following
table can be used to determine the problem and
possible causes.
NOTICE
If ame is not established within 15 seconds of
oil valve actuation (known as Trial For Ignition
[TFI]) lockout will occur. Lockout is indicated
by a red LED solid-on located on the oil primary
control.
Hard Lockout will occur if the Oil Primary
Control locks-out three (3) times during a call
for heat. This is indicated by red light reset
button solid-on.
D. BEFORE TROUBLESHOOTING
The following pages contain trouble shooting tables for
use in diagnosing control problems. When using these
tables the following should be kept in mind:
1. This information is only meant to be used by a
professional heating technician as an aid in diagnosing
boiler problems.
2. Where applicable, follow all precautions outlined in
Section IX, System Start-Up .
3. In general, these tables assume that there are no loose
or miswired electrical connections. Before using these
tables inspect all electrical connections on the boiler to

63
Possible ERP (External Error) Values:
Display Status Recommended Corrective Actions
Err 1 Temperature Sensor Fault
Temperature sensor failure, wire harness loose or shorted connection or control
hardware failure:
- Check sensor is securely attached to boiler control
- Check that sensor wire is not damaged
- If secure and in good condition, replace sensor
- If problem persists, replace control
Err 2 Communication Fault
Enviracom terminal is shorted to ground or line voltage.
- Check wiring to EnviraCOM terminals 1,2 and 3. Wiring to external EnviraCom
device is incorrect.
Err 3 Internal Hardware Fault Error detected with AC power supply frequency or boiler control failure. Cycle power to
the control. Replace control if problem persists.
Err 4 Burner Output (B1) Fault
B1 output sensed powered during safety output relay check sequence or un-powered
during running, or powered in idle in combination with water temperature above 264°F
limit. Cycle power to the control. Replace control if problem persists.
Err 5 Line Voltage Fault (< 80 Vac) AC voltage out of specication high or low; check L1, L2, 110 VAC.
Err 6 Fuse missing
Internal fuse is blown or missing. The fuse protects the Aquastat from miss wiring the
L1 and L2 on Oil Primary. When the Oil Primary is correctly wired the fuse is useless
and not detected. If Primary is wired incorrectly the fuse is blown out and Aquastat
report error 6. EnviraCOM message is sent when the wiring is xed and the error
disappears to indicate the end of the error state. Check wiring and replace fuse.
Err 7 User settings lost, (reset to
factory defaults)
Warning: Generated if user adjustments are lost and the device uses factory default
values. Error is cleared by entering and exiting the Adjustment mode. Replace control
if problem persists.
Err 8 Manual Reset Lockout
(resettable)
Set if Err 4 was invoked four times in a row. Check wiring and clear Lockout by
pressing all three user keys for 30 seconds.
XIII. TROUBLE SHOOTING (continued)
E. USE BOILER CONTROL DISPLAY ERR AND ERP NUMBERS TO DIRECT TROUBLESHOOTING
If the Boiler Control detects an error it will ash "Err" (boiler control error) or "ErP" (external error) followed by a number.
Use this text and number to identify the boiler problem and corrective action in the table below. If there is no error display
proceed to Paragraph E:
TABLE 14A: BOILER CONTROL ERROR NUMBERS
make sure that they are tight. Also, check the wiring
on the boiler against the wiring diagram in Figures
28A, 28B and 28C. Ensure that incoming 120 Vac
power polarity is correct and that the boiler is properly
grounded.
4. A defective control or component is generally the least
likely cause. Before replacing a component, try to rule
out all other possible causes.
5. When checking voltage across wiring harness pins
be careful not to insert the meter probes into the pins.
Doing so may damage the pin, resulting in a loose
connection when the harness is reconnected.
ErP
Value Description
4Warning, Cad Cell Resistance High (Service Required)
5No Ignition, Check Cad Cell
9Warning, Flame Proven, Late in Trial
10 No Ignition, Check Ignition Transformer
18 Internal Error, Electronics Failure
20 No Ignition
21 No Ignition, After Flame Loss During Run
22 Flame Lost During Run Three Times In A Row
23 Flame Out of Sequence, During Pre-Purge
24 Flame Out of Sequence, During Post-Purge
25 Oil Primary Lockout, Manual Reset Required
ErP
Value Description
34 Cad Ohms Permanently Low (Flame Out of Sequence)
35 Duplicate Zone
58 AC Line Frequency Error
59 AC Line Voltage Error
84 Low Water Event
89 Communication Lost
91 Communication Error
119 Sensor Failure
140 Low Probe Signal
141 Manual Reset Lockout
Possible ERP (External Error) Values (continued):

64
XIII. TROUBLE SHOOTING (continued)
E. USE BOILER CONTROL DISPLAY ERR AND ERP NUMBERS TO DIRECT TROUBLESHOOTING (continued)
Display Status Recommended Corrective Actions
ErP 4
Warning, Cad Cell
Resistance High
(service required)
The cad cell resistance is higher than normal while running, the system is in need of a tune
up.
- Check for proper alignment of the cad cell and clean the eye if necessary.
- Check if the pump is generating adequate pressure.
- Check burner adjustments (refer to burner manufacturers instructions).
- Check for excessive soot build up in the burner and ue.
- Check for ue blockage.
ErP 5
No Ignition,
Check Cad Cell
The cad cell detected some amount of light during the ignition trial, but not enough to enter
run mode.
- Check the cad cell positioning and clean the eye.
- Set the display to show the cad cell resistance.
- Shield the cad cell from light.
If the display shows is less than 20,000 ohms, unplug the cad cell,
if the display does not read 999999 ohms, replace control,
if it does read 999999 ohms, replace cad cell.
- Expose the cad cell to ambient light (generally enough light to read by is adequate)
If the display shows more than 2000 ohms, short the cad cell terminals,
if the display shows more than 5 ohms, replace control,
if less than 5 ohms, replace cad cell.
If the burner still does not light, proceed to "No Ignition", ERP 20 corrective action.
ErP 9
No Ignition,
Check Cad Cell
The burner lit very late during the trial for ignition and is susceptible to not lighting.
- Check cad cell for proper alignment and clean if necessary.
- Check burner adjustments (refer to burner manufacturers instructions)
- Check electrodes and spring contacts (if equipped) and adjust per manufacturers
recommendations.
- Check if the pump is generating adequate pressure.
- Check the fuel supply lines and lter for obstructions.
ErP 10
No Ignition,
Check Ignition
Transformer
The burner was not lit and spark was not detected. Check the electrodes, spring contacts
(or high voltage wires), and ignition transformer for proper operation.
If spark ignition is functioning acceptably, proceed to "No Ignition", ERP 20 corrective action.
ErP 18 Internal Error,
Electronics Failure
The Erp 18 display may indicate any one of the following:
Check Oil Primary and Option Panel Displays:
- If Option Panel display shows “Err 3“, IQ Option Card Communication Error: the Erp 18
error is caused by the option card. Replace defective card if error persists
- If The Oil Primary is locked out with “Internal Error” replace control if the error persists.
ErP 20 No Ignition
- Check that fuel tank is not empty.
- Check that the manual shut off valve is open.
- Check that the burner motor is spinning and the pump is generating adequate pressure.
- Check the condition of the nozzle and replace if necessary.
- If a valve is present, check for proper operation.
- Check burner adjustments (refer to burner manufacturers instructions)
ErP 21
No Ignition,
After Flame Loss
During Run
- Check for excessive airow or draft causing ame to leave burner head.
- Check for back pressure causing ame to be erratic.
Re-ignition Failure, Flame was lost and could not be relit .
ErP 22 Flame Lost During Run
Three Times In A Row
Flame was lost more than the allowed number of times. The burner lights, but does not
remain lit.
- Check that the fuel tank is not empty.
- Check the condition of the nozzle and replace, if necessary.
- Check the fuel supply lines (and lter) for obstructions or air
- Use the pump priming feature to purge the system of air
- Check the burner motor is spinning and the pump is generating adequate pressure.
If present, check operation of the oil valve.
If the problem persists, proceed to the "Cad Cell, High During Run", ERP 4 corrective action.
TABLE 14B: EXTERNAL DEVICE (Oil Primary, Option Card, etc.) ERROR NUMBERS