Is power available in wall outlet? MONITOR 441 HEATER GENERAL CHECKS Is power available in wall outlet? Is power plug inserted in wall outlet? Has there been a power interruption? (Display window shows 88.88). Has Circulation Fan stopped? Is there fuel in tank? Is tank valve open? Has Fuel Constant Level Valve Set Lever raised and lowered? Is ON/OFF switch ON? Is operation mode on Manual? Is set temperature in High position? Is Fusible Link Valve "open"? NOTE: Air Damper in the following Flow Charts refers to the round disk that is installed over the flue pipe air intake flange. There are different ones for the standard installation and installations with flue pipe extensions. pg. 46A

1. Is Igniter red? Check visually through the Combustion Chamber viewing window or feel igniter cover after 3.5 minutes prepurge preheat. It should be warm to the touch. Replace or check Circuit Board Failure of Circuit Board Incorrect wiring of Flame Sensor or Ground Correct wiring. Is there flame? 1. Yes Correct or change Is RUN lamp lit? Flame Sensor Rod touching burner parts. Yes No Ignition No Replace Air Pressure Switch Yes Does Combustion Blower motor operate? Failure of Air Pressure Sensor Replace Solenoid Pump No Failure of Solenoid Pump Yes Reset the fuel Constant Level Valve Has Constant Level Valve safety tripped? No No Replace Combustion Blower Motor NOTE: PCB stands for Printed Circuit Board Failure of Combustion Blower Motor 1. Push ON/OFF Switch OFF 2. Remove Igniter 3. Disconnect wiring for Solenoid Pump. 4. Push ON/OFF Switch ON Is wiring correct? Yes Failure of Circuit Board Replace or check Circuit Board No Incorrect wiring Correct wiring Soot adhering to combustion chamber interior Clean gently with brush, etc. Is Igniter red? Yes Failure of Solenoid Pump Replace Solenoid Pump Is Display Window lit? Replace Igniter Yes No Failure of Igniter Is there 110V at "B" pins on Circuit Board? Replace or check Circuit Board Failure of Circuit Board Yes No Correct wiring Incorrect wiring Failure of Igniter relay on PCB. Replace board Check Fuse (F1) Is there 110V at "B" plug? Normal No Replace or check Circuit Board Failure of Circuit Board Put in Manual mode Open Is on Auto operation mode? Change Fuse; plug in power cord Replace or check Circuit Board Failure of Circuit Board Normal Previous Fuse open Leave in new Fuse Short circuit of lead wire Correct or change Open pg. 46B Failure of Circuit Board Replace or check Circuit Board

2. 3. 4. 5. Is Solenoid Pump operating? Is there water in the fuel? Water gathering in fuel tank Discharge water Is air trapped in fuel line? Yes Yes Yes No fuel feed; No Ignition Fuel not fed because of surface tension of water Clean burner joint Burner joint clogged (Fuel Line pas- sageway into Combustion Chamber near base of Burner Pot) Replace handle of fusible link valve or open valve No No No Check wiring to plug "K" Fusible link valve closed on M-422 Reset fuel Constant Level Valve Normal Tripped safety on fuel Constant Level Valve Replace Solenoid Pump Correct or replace wires Failure of Solenoid Pump Abnormal Wiring failure Straighten fuel line to remove air pocket, or correct fuel line installation Air lock 3. Is Fuel Constant Level Valve Lever set? Yes Push Fuel Constant Level Valve Lever 4 or 5 times Extinguished soon after Ignition Fuel not entering into valve 1. Push ON/OFF Button to "OFF" 2. Refuel heater 3. Turn heater on No Fuel shortage Overheat condition 1. Unplug heater 2. Remove air-flow obstructions and/or determine cause of overheating 3. Replace cover & restart heater Make GENERAL CHECKS from previous page. Is fuel head too low? See Section 2: INSTALLATION If using a Lifter, check Lifter installation specifications. Is unit placed horizontally? Is fuel line length correct? 4. Normal Air present in fuel line Flame does not increase when set at "High" Is Display Window lit? Yes Correct fuel line Failure of Solenoid Pump Replace Solenoid Pump Wiring failure Correct wiring No Failure of Solenoid Pump Replace Solenoid Pump Failure of Circuit Board Replace or check Circuit Board 5. Abnormal Not as specified Correct as specified Allow heater to cool completely. Tighten all connections. Poor flame; sounds of combustion; soot at the reat of the heater. Is not a failure, but is apt to occur. Loose flue pipe pg. 47

6. 7. Is unit placed horizontally? Is flue pipe too long or have too many bends? See Section 2: INSTALLATION Does Combustion Fan work properly? Check for obstructions such as wasps nests in exhaust or air supply piping 6. Does Damper Solenoid work properly? Normal Normal No Smoke produced when set "High" Failure of Damper Solenoid Assy Replace Damper Solenoid Assy Yes Check outside of flue pipe for flow of air and exhaust Abnormal Abnormal Abnormal Clean out intake and exhaust ducts Intake or exhaust line clogged Normal Is Air Damper installed according to specifica- tions? Yes Fuel Solenoid Pump malfunctioning Replace Solenoid Pump No Install Air Damper ac- cording to specifications Combustion Fan failed Replace Combustion Blower Assembly Clogged air supply or exhaust piping Remove obstructions Not as specified Correct as specified 7. Is igniting time too long? (Usually 0.5 to 1 min) Is Air Damper installed according to specifica- tions? Combustion noise is made soon after igniting Normal Normal See Symptom #5 Abnormal Abnormal Mount Air Damper as needed Too much air flow Igniter mounted incorrectly Mount properly pg. 48A

8. Is fuel pure kerosene? Is heater mounted horizontally? Is external fuel tank too low? (See Section 2: INSTALLATION) Install Air Damper as needed (see Symptom #5). Is there an obstruction in the Combustion Air System? 8. Does flame extend to whole area of burner? Is Igniter properly installed? Combustion Chamber window gets smoky after running Normal Yes Yes Install Combustion Ring properly Combustion Ring is installed improperly No Combustion Ring is broken Replace Combustion Ring Assembly No Replace gasket; correctly install cover Air leaks from Igniter cover Switch Set temperature to High & Low 5-6 times Flame extends Supplies only a small amount of fuel due to dust or bubbles in fuel delivery parts Instruct customer about filter & reset lever Abnormal Flame does not extend Failure of Solenoid Pump Replace Solenoid Pump Not as specified Correct as specified pg. 48B

9. Is window curtain too close to the rear of the unit? Is Circulation Fan Guard dusty? 9. Yes The Overheat Thermostat is activated Window curtain or other obstruction covers circulation air inlet. Clean guard Keep curtain from unit No Does Circulation Fan operate properly? Yes Obstacle covers circulating air outlet Remove obstacle No Failure of Printed Circuit Board Replace or check PCB Circulation Fan failed Repair Fan Motor Incorrect wiring Repair or replace wiring pg. 49

10. Does 88.88 blink in the display window? Is there fuel? (M-422) Is Empty LED lit? (M-422) Failure of resistor R38 - R39 Yes Yes Yes If problem is found to be in the PCB, do not attempt to repair. Replace & send PCB through your distributor to MPI for repair. No operation Failure of capacitor C20 No Plug in AC cord No Is temperature displayed in display window? No Failure of resonator XL1 Yes Press ON/OFF button to ON Failure of resistor R59 Failure of microprocessor IC1 No NOTE: PCB stands for Printed Circuit Board Remove the connector CN1 of operation circuit board from PCB and then jumper pins T1 & T6 on PCB Replace operation circuit board CN1 Failure of operation circuit board CN1 Does heater start to operate? Yes Failure of resonator XL1 Failure of resistor R59 NOTE: DC voltages are measured with respect to EP on PCB No Failure of microprocessor IC1 No fuel Refill fuel At AC cord plug-in, does voltage at TP7 turn High from Low? Failure of Microprocessor IC-1 Is there 12VDC at TP3? Is there 5VDC at TP2? Yes Yes Yes Failure of comparator IC13 Failure of resistor R29 - R32 No No Failure of capacitor C18 No Failure of switch SW1 (Reset) Failure of IC2 Failure of capacitor C9 Fuse F1 open Replace fuse Failure of transformer Replace transformer Failure of diode D6 - D9 pg. 50 Failure of capacitor C8

11. Does Combustion Blower work during prepurge & igniting? Is Igniter red on preheat? Does Air Pressure Switch work normally? A on next page Yes Yes Yes No ignition No No No Replace air pressure switch Failure of air pressure switch Rubber hose is blocked or disconnected Clear or connect rubber hose Incorrect wiring Correct wiring Failure photo-triac IC8 Failure of triac Q1 Is there 12VDC between TP3 & IC6 pin 13? Failure of resistor R1, R51 Yes Failure of capacitor C2 Replace combustion blower Failure of combustion blower Incorrect wiring of combustion blower No Correct wiring Failure of microprocessor IC1 Failure of inverter array IC6 Is there 12VDC on coil of relay RL1 on preheat? Failure of relay RL1 Yes Fuse F2 open Replace fuse Igniter open Replace igniter No Failure of microprocessor IC1 pg. 51 Failure of inverter array IC6

11. A from previous page Does Solenoid Pump work? Yes Check fuel supply parts Failure of fuel supply parts No Failure of resistor R2 - R9 Failure of capacitor C4 - C6 Failure of zener diode ZD1 Is there 160VDC across diode bridge D2? Failure of diode D3 - D5 Yes Failure of trigger diode TD Failure of thyristor Q2, Q3 No Failure of diode bridge D2 Failure of microprocessor IC1 Failure of inverter array IC6 Failure of diode D17 Failure of resistor R53 Failure of photo-triac IC11 Failure of transistor Q6, Q11 pg. 52

13. Is there 1.2VDC on IC3 pin 6? Is there more than 1.3VDC at TP6? Yes Yes Yes Flame failure Failure of comparator IC3 No No No Failure of microprocessor IC1 Is there 0.2VDC or less on Q7 collector? Failure of resistor R33, R34 Yes Incorrect installation of flame sensor rod Correct installation Failure of wiring for flame sensor and ground Correct wiring No Failure of resistor R27 Failure of diode D19 Failure of capacitor C29 Failure of transistor Q7 Failure of transformer Replace transformer Failure of capacitor C14 - C16 Failure of resistor R10, R22 - R24 Failure of resistor R18 - 21, R25 pg. 53A

O N 13. FLAME ROD BYPASS CIRCUIT For testing purposes: a flame detector rod bypass circuit can be made up, consisting of 2 insulated alligator clips, 2 - 6" pieces of insulated copper wire, 1 - 1/4 watt 400 Volt diode, and 1 - 1/4 watt 100K resistor. These components are to be soldered together in sequence as shown in the diagram below (note component sequence & polarity.) Once the bypass circuit is made, turn the unit on. Immediately after the prepurge preheat cycle, when the mode light comes on, disconnect the wires from the O and N pins on the PCB and replace with the bypass circuit. The unit should then continue functioning as though it had a good flame inside the burn chamber, and service tests such as fuel flow can be checked. Note: WARNING, after all tests are completed, replace original flame rod wires, as it is a vital safety issue. O N 1N4004 100K Clips pg. 53B

14. Failure of microprocessor IC1 Connect 10K resistor to Q pins on PCB and then set temperature from Low to High Is temperature display normal? Is solenoid pump able to change fuel flow rate? Is circulation fan motor able to change speed? Yes Failure of inverter array IC6 Change of burn mode: High--Low, is improper Yes Yes Failure of photo-triac IC8, IC9 Failure of triac Q1 No No No Failure of resistor R1, R51, R52 Failure of capacitor C2 Failure of Combustion Blower Replace combustion blower Failure of resistor for Combustion Blower Replace resistor for Combustion Blower Failure of Damper Solenoid Replace damper solenoid Failure of photo-triac IC7 Failure of microprocessor IC1 Failure of inverter array IC6 Failure of circulation fan motor Replace circulation fan motor Failure of microprocessor IC1 Failure of photo-coupler IC12 Failure of inverter array IC6 Is there approx. 2.8VDC at TP4? Failure of solenoid pump Replace solenoid pump Yes Failure of microprocessor IC1 Failure of resistor R12, R13 No Failure of capacitor C11 pg. 54