Laars NeoThem NTH Service Manual Download Page 28

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Service Manual - NeoTherm 500

Checking the Low Water Cutoff Switch (option)

Control resets?

Yes

Check for continuity from

base of switch to ground.

Has continuity?

Isolate the boiler and drain it.

Remove the probe.

Do not use Teflon tape on the

threads. (This would interrupt the continuity).

Use “pipe dope” instead.

Check for water in boiler?

Yes

Water present?

Yes

Check water supply, water pressure,

and auto makeup valve.

Reset low water cutoff control

Continued next page

Are you using ultra-pure water?

Ultra-pure water?

Yes

Ultra-pure water will not conduct

electrical current = false low water reading

OK - temporary condition

Summary of Contents for NeoThem NTH

Page 1: ...Document 1292 Modulating Boiler Model NTH Sizes 399 850 MBTU h Water Heater Model NTV Sizes 399 850 MBTU h Every reference that you ll need to service the Commercial NEOTHERM Service Manual for NeoTherm ...

Page 2: ......

Page 3: ...rts in Section A The instructions in Section A will lead you to more detailed procedures in Section B Section C covers possible combustion problems and the combustion setup procedure For details on the User Interface used on your unit see Section D If the unit presents a Hold or Lockout message you can get more infor mation from the listing in the Appendix Contact Laars Technical Support if you ca...

Page 4: ...des several ways of locating information From the line at the top of the screen select Edit then Find Type in the item you want to find The PDF Reader will take you to the first occurrence of that item To go to the next occurrence click on the right arrow Table of Contents The Table of Contents is located at the beginning of the manual The bookmark for Contents will take you there Use this to iden...

Page 5: ... dam age Improper installation and or operation will void the warranty Fire or Explosion Hazard Improper configuration can cause fuel buildup and explosion Improper user operation may result in death severe physical injury or property damage Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance What to Do If You Smell Gas If any odor of g...

Page 6: ... This appliance must be electrically grounded in accordance with these codes Hot Water This unit can produce water which is hotter than 125 F 52 C This can cause severe burns instantly or death from scalding Always shut off the system and allow it to cool for one hour before opening any pipe connec tions that may contain hot water Children disabled and elderly persons are at the highest risk of be...

Page 7: ...nly Unit with Current User Interface 10 A10 Unit is Noisy 10 Section B Troubleshooting Procedures Sect Title Page B1 Quick Check of Components in the Safety Chain 11 B2 Troubleshooting the 24V AC Power Supply 15 B3 Checking the Safety Interlocks 16 B4 Checking the Low Water Cutoff Switch 18 B5 Controller for Low Water Cutoff 19 B6 Removing and Replacing the Low Water Cutoff Switch 20 B7 High Water...

Page 8: ...wer 41 B23 Removing and Replacing the Blower 42 B24 High Stack Temperature Fault 46 B25 Removing and Replacing the Stack Temperature Limit Switch 47 B26 Checking the System Sensor 48 B27 Checking the DHW Sensor 48 B28 Inlet Water Temperature Sensor 49 B29 Removing and Replacing the Inlet Water Temperature Sensor 49 B30 Outlet Water Temperature Sensor 50 B31 Removing and Replacing the Outlet Water ...

Page 9: ...rm Control System Sect Title Page D1 Identifying the User Interface on Your Unit 73 D2 Using the Original White User Interface 74 D3 Reacting to Lockouts on the Original White User Interface 76 D4 Removing and Replacing the Original White User Interface 77 D5 Using the Current User Interface 78 D6 Reacting to Lockouts on the Current User Interface 84 D7 Removing and Replacing the Current User Inte...

Page 10: ...Service Manual NeoTherm 500 viii ...

Page 11: ...White User Interface 7 A6 Unit is Running but Building is Still Cold 8 A7 Control Unit Says Run but Boiler is Not Firing 9 A8 Open Safety Chain Fault 63 9 A9 Unit Runs in High or Low Fire Only Current User Interface 10 A10 Unit is Noisy 10 New installation never ran correctly Old installation ran correctly See Quick Check of Components in the Safety Chain and Firing Sequence Section B1 Is this a n...

Page 12: ...2 Checking the Blower See Section B19 Checking the Air Pressure Switch Blower related problem Disconnect sensor for Outdoor Reset if used No System operates normally Yes See Section B33 Troubleshooting the Outdoor Reset System continued Yes Yes Short contacts Central Heat 5 6 on TB7 DHW 5 6 on TB6 Original user interface shows Check Pre Purge Run Normal operation Current user interface shows Heat ...

Page 13: ...c See table of code numbers in Appendix Problem indication from controller Yes Code number supplied No See Section A4 Control Unit is in Standby Mode Controller stuck in Standby mode No Replace the SOLA controller See Section D8 D9 Settings OK Yes Yes Adjust regulator Check with gas company Incoming gas pressure is OK No Yes Correct the settings No ...

Page 14: ... condition the blower is running continuously but the display is completely blank If unit continues to operate normally temporary condition If breaker trips again See Section B2 Reset 24V breaker switch under trans former Resets Yes No Check the 24V power supply See Section B2 ...

Page 15: ... weather shutdown is enabled Outdoor air temperature too warm Normal operating condition In certain situations the controller on this unit can go into Standby mode The Boiler pump is running so the unit sees a Call for heat There is no lockout or hold but something is preventing it from going to Run mode No Unit operates normally Disconnect outdoor temp sensor Yes See Section B33 Troubleshooting O...

Page 16: ...sor Unit will not run for 20 min then automatically resets Controller reacting to a temporary problem No Units with original white user interface See Section A5 Changing Control Settings Change Not Complete Were you changing the control settings Yes No See Section B3 Checking the Safety Interlocks Problem with safety interlock circuit ...

Page 17: ... the controller However if you do not press Done or OK the control ler will go into the Standby mode The setting for the DHW setpoint will remain at the old setting 180 because at this point the controller still has not received the new setting More importantly the unit will not fire because it is still waiting for that new setting There is no indication of this on the User Interface To recover fr...

Page 18: ...es No Clear it Air inlet is blocked Clean Air intake inside unit is plugged Yes No Clean blow out Gas air mixture is correct but not enough gas air mixture is supplied Dirty fan Yes No Burner and or heat exchanger plugged Yes See Cleaning the Burner and Heat Exchanger Section C5 ...

Page 19: ...ocked condensate drain Blocked exhaust vent High or low gas pressure Low water in system Problem with circulator pump Fault 63 is a bit like the Check Engine light in a car it indicates a problem but does not identify the problem To identify the specific problem see Section B3 Checking the Safety Interlocks A7 A8 No Example Stack temp limit trips automatically resets after 20 minutes Until this ha...

Page 20: ... Noisy A10 On systems using the Current user interface To see if the unit is locked into high fire or low fire From the Home screen press i to go to the Info Install screen High light Test and press OK In the Test menu highlight Manual Burner Operation and press OK Be sure Firing Control is set to Auto If it is not log in using the password lnt and change the setting to Auto Unit Runs in High or L...

Page 21: ...r the Outdoor Reset function is connected disconnect it at terminals 1 and 2 on TB 7 on the control board See Fig B1 1 Remember to re connect the sensor when you are done If the unit operates with the Outdoor Reset sen sor disconnected go to Section B33 Trouble shooting the Outdoor Reset System 3 Turn off the Anti Short Cycle function by setting it to the minimum value 4 If you are working with a ...

Page 22: ...cks are connected or jumpered out and the switches are closed allow ing the unit to fire when a call for heat arrives If you see 24V AC here this means that the following safety interlock switches are OK Low water cutoff switch High water temperature limit switch Flow switch If 24V AC is not present go to Section B3 Check ing the Safety Interlocks FIELD INTER LOCK REMOTE ANALOG INPUT OUTDOOR TEMP ...

Page 23: ...on B16 Condensate Trap Level Switch 11 If you see 24V AC at J6 1 this means that all of the switches in the safety chain are satisfied The blower should run and then the pressure switch should close allowing the ignition se quence to start To check the pressure switch check for continuity no resistance between ter minal 1 on J6 and terminal 1 on J5 on the control module See Fig B1 7 If the pressur...

Page 24: ...rough J2 on the control module See Fig B1 8 If power is available at J2 but the blower is not running go to Section B22 Checking the Blower If the blower is running and the unit does not fire go to Section B32 Testing the Temperature Sensors 13 Replace all of the wiring you changed earlier Remove the jumper for the call for heat TB7 5 6 Reconnect the outdoor temperature sensor TB7 1 2 Reset the An...

Page 25: ...0V AC incoming voltage 120V AC at main power switch 3 7 on SW1 No Disconnect power Check for continuity through power switch SW1 Replace if necessary Disconnect power Check transformer see Section B34 Replace if necessary Reset circuit bkr on transformer 24V OK now Yes 24V AC supply is OK Why did breaker trip Loose or damaged wire No Check for bad transformer Trans OK Yes ...

Page 26: ...AC is present Yes See procedure B4 Checking the Low Water Cutoff Switch No Check for 24V AC between TB8 3 and TB4 1 24V AC is present Yes Check the optional external high limit switch 1 Check for actual high outlet temp condition manual reset 2 Check temp setting on switch 3 Replace switch No Check for 24V AC between TB8 5 and TB4 1 24V AC is present Yes See procedure B8 Checking the Flow Switch C...

Page 27: ...With boiler attempting to run check for 24V AC across two leads on air pressure switch 24V AC is present switch open Yes See procedure B16 Checking Condensate Trap Level Switch No 12185 See procedure B19 Checking the Air Pressure Switch NT unit should be trying to fire If not firing control panel should be displaying an error code See Error Codes in Appendix 2 12 ...

Page 28: ...be Do not use Teflon tape on the threads This would interrupt the continuity Use pipe dope instead Check for water in boiler Yes Water present No Yes Check water supply water pressure and auto makeup valve Reset low water cutoff control Continued next page Are you using ultra pure water Ultra pure water Yes No Ultra pure water will not conduct electrical current false low water reading OK temporar...

Page 29: ... 1 The controller has two LED indicators Power red When lighted the control box has power Tripped yellow When lighted the controller has detected a low water condition The controller also has two switches Reset Use this to cancel the trip condition Test This simulates a low water condition See Removing and Replacing the Low Water Cutoff Switch Section B6 Fig B5 1 Controller for low water cutoff Ch...

Page 30: ...front panel 2 Isolate the boiler Turn off the water shutoff valves located upstream and downstream of the unit 3 Drain the boiler 4 Unlock and open the front panels on the unit Turn the two wingnuts and swing out the center electrical panel Now you will have easy access to the probe as shown in Fig B6 1 5 Disconnect the probe wire and the ground wire 6 Use two pipe wrenches to unscrew the probe as...

Page 31: ...nd wire Use the 5 16 socket to loosen both of these Remove the green ground wire from the left hand screw Twist the box slightly and pull it away from the backing plate 4 To reassemble reverse the procedure we have just described Remember to attach the green ground wire to the inner sheet metal screw 5 16 head Fig B6 2 Connections to low water cutoff control Fig B6 3 Control for low water cutoff w...

Page 32: ...ontrol Other switches will reset auto matically Correct the cause of the problem and or replace the switch Checking the Flow Switch optional B7 B8 Warning Do not leave the room while unit is operating with the flow switch bypassed Remove the jumper as soon as the test is complete Flow present No Yes Check for line voltage at the circulator pump terminals 1 2 on TB5 Momentarily jump switch TB8 6 to...

Page 33: ...eter to test the continu ity through the switch With no water flow and the paddles in the relaxed position standing upright the switch should be open Note There is a seal at the base of the paddle as sembly If this seal fails it can allow water to leak into the connection box From there the water can flow through conduits to other parts of the control system in the Magna Therm unit If it is necess...

Page 34: ... sandpaper Pipe dope or Teflon tape Procedure 1 Turn off power to the system Use the main disconnect switch mounted above the front panel 2 Isolate the boiler Turn off the water shutoff valves located upstream and downstream of the unit 3 Drain the boiler The drain valve is located xx 4 Remove the cover from the control box for the switch Note the positions of the wiring connections then disconnec...

Page 35: ...partially block ing the flow The flowing water should hit the longer paddle first See Fig B10 1 9 Note the arrow and the word Flow on the large mounting nut This will help you to install the paddles in the correct orientation 10 Coat the threads with pipe dope or Teflon tape and install the part Important With the pipe wrench tighten so the paddles sit in the orientation shown above Be sure the ar...

Page 36: ...e arranged Fig B11 1 Gas shutoff valve typical B11 Tools and equipment required Small Phillips head screwdriver 1 3 8 and 5 16 sockets 4 mm Allen wrench Two medium sized pipe wrenches Gas resistant pipe dope or Teflon tape Gas leak detection solution bubble spray Container for removed parts Procedure 1 Turn off power to the machine Use the main discon nect switch on the front of the machine just a...

Page 37: ...ted this wire will go to the N C connection 7 On the left end of the assembly remove the four bolts which attach the gas assembly to the blower See Fig B11 4 The 5 16 socket will fit the head of each bolt Use the 3 8 socket on the nut on the other end 8 On the right end of the assembly remove the four socket head cap screws which at tach the gas inlet pipe to the assembly See Fig B11 5 Use the 4mm...

Page 38: ...screw the large T nipple from the gas valve 12 Figure B11 7 shows the gas valve after it has been removed Notice the rubber washer be careful to install this correctly when mounting the new valve 13 To reassemble reverse the procedure listed above Keep the following points in mind during reassembly We already mentioned the rubber washer on the gas valve When re attaching any parts which have pipe ...

Page 39: ...o the atmosphere 24V AC present switch open Yes Check gas supply Call gas company Gas pressure should be lower than 13 w c Check for 24V AC across the switch Reset the switch manually by pressing the button WARNING Never jump this switch Switch resets No Yes Temporary drop in gas pressure Switch is OK Gas supply OK No Call the gas company and correct the problem If the switch was tripped you will ...

Page 40: ... present switch open Yes Check gas supply Call gas company Gas pressure should be greater than 3 w c Check for 24V AC across the switch Reset the switch manually by pressing the button WARNING Never jump this switch Switch resets No Yes Temporary drop in gas pressure Switch is OK Gas supply OK No Call the gas company and correct the problem If the switch was tripped you will feel a resistance The ...

Page 41: ...nit is open Figure B14 1 shows the gas train Connect a test gauge to the inlet gas pressure tap The low pressure switch Honeywell p n C6097A is wired N O normally open and requires a manual re set You will need to reset this switch if you disconnect an old switch or install a new switch The low pressure switch is set to trip below 3 W C water column Fig B14 1 Inlet gas pressure tap Inlet gas press...

Page 42: ...set switch You will need to reset this switch if you disconnect an old switch or install a new switch The low pressure switch is set to trip below 3 w c water column The high pressure switch Honeywell p n C6097B is wired N C normally closed The high pressure switch is set to trip above 3 w c water column Removing and Replacing the High and Low Gas Pressure Switches Tools and equipment required Sma...

Page 43: ...right side of the machine yellow handle 4 Disconnect the wires to the gas pressure switch Remove the front cover on the gas switch by remov ing the two screws Before disconnecting the wires note the way they are connected to the switch Fig B15 2 Gas shutoff valve typical Fig B15 3 High gas pressure switch cover removed For the high gas pressure switch only Mark the wire on the left using a piece o...

Page 44: ...mble reverse the procedure we have just described Use gas resistant pipe dope or Teflon tape on the threaded joints For both the high gas pressure and low gas pressure switch es check the setting on the adjusting knob Both switches should be set to 3 w c Important Remember to reset the low pressure switch before you place the NT unit in operation Every low pressure switch will need to be reset whe...

Page 45: ...tch 24V AC present switch open No Yes See Section B3 Checking the Safety Chain Check for 24V AC across switch Test switch See Section B17 Replace if necessary See Section B18 Outlet blocked No Yes Flush outlet with water Check for blocked or frozen condensate outlet B16 ...

Page 46: ...Magna Therm unit is designed to operate in the condensing mode The combustion of natural gas produces a lot of water vapor In the NT unit this water vapor is condensed out of the exhaust gas inside the heat exchanger The water is collected from the bottom of the heat exchang er and sent to the condensate trap The trap includes a float valve If the condensate drain is plugged or blocked for some re...

Page 47: ... the mounting screws then remove the right side panel 4 Disconnect the two wires from the top of the trap assembly 5 Notice the position of the Ty wrap then cut it 6 Use the water pump pliers to remove the clip holding the inlet hose lower end of the trap assembly Pull the end of the hose away from the trap assembly 7 Once the assembly is free flush it out with water to remove any col lected sedim...

Page 48: ...intake and exhaust vents Clean with a shop vac Dirty fan Yes No Test the air pressure switch See Section B20 Switch is OK No Replace switch Yes Problem with blower Yes See Section B22 Checking the Blower No Heat exchanger is plugged Yes Clean the heat exchanger See Section C5 B19 Checking the Air Pressure Switch Blower Proving Switch ...

Page 49: ...e continuity low Ohms switch closed Without pressure You should not see continuity high Ohms switch open 4 Disconnect the T Attach a manometer to the negative port on the blower When the fan starts you should see a vacuum of about w c Removing and Replacing the Air Pressure Switch Fig B21 1 Air pressure switch typical The air pressure switch acts as a blower proving switch to ensure that the blowe...

Page 50: ...se the pliers to release the hose clamps and re move the air hoses from the bottom of the switch Important During reassembly the hoses must be connected to the correct barbs on the switch Do not reverse the connections To prevent this you should mark one of the hoses Remove the front hose first Mark the rear hose with a piece of electrical tape then remove the rear hose 5 To reassemble reverse the...

Page 51: ...es Check wiring harness Wires OK No Replace wire harness No Has call for heat At start of test unit should be ready to run Standby Blower runs Problem with temp sensor s System sensor Section B26 DHW sensor Section B27 Short contacts for call for heat CH TB7 5 6 DHW TB6 5 6 Blower does not run Bad blower Replace the blower See Section B23 B22 Checking the Blower ...

Page 52: ...alent Replacement gasket for front plate of heat ex changer Container for removed parts Procedure 1 Turn off power to the machine Use the main dis connect switch on the front of the machine just above the control panel 2 Remove the front and right side panels 3 Shut off the gas at the gas shutoff valve on the right side of the machine yellow handle See Fig B23 1 4 On the left end of the gas valve ...

Page 53: ...b is to separate the front plate on the heat exchanger from the rest of the unit See Fig B23 5 Note the two large wires running to this assembly The spark wire and the flame sense wire look alike The unit will not run if you reverse these wires Before removing the wires mark the spark wire with a piece of electrical tape Also disconnect the green ground wire B23 3 Gas and air intakes disconnected ...

Page 54: ...very time you clean the unit or remove the front cover of the heat exchanger 9 Once the assembly has been removed it looks like Fig B23 7 Remove the four 13mm screws that attach the blower to the assembly 10 Next separate the Venturi from the blower Re move the six 25 Torx screws See Fig B23 8 Remove these nuts B23 6 Removing the front of the heat exchanger B23 7 Blower front plate and burner asse...

Page 55: ...14 When attaching the front cover of the heat exchang er tighten the nuts in a cross pattern See Fig B23 10 If you tighten all of the nuts on one side first this might bend or distort the cover 15 Check for gas leaks using a leak detection solution 16 Finish reassembling the unit and turn on the power and gas Check for proper venting and combustion air Fire the boiler and check the combustion usin...

Page 56: ...ck temperature limit to 190 F Actual stack temperature problem Check the continuity on the wires from the sensor to J9 4 J9 5 and J9 6 on the control module Wiring to sensor is correct Good connections No Yes Fault disappears No Replace the control module Replace the sensor See Section B38 Problem with circulator pump Yes No B24 High Stack Temperature Fault ...

Page 57: ...tch mounted above the front panel 2 The stack temperature limit switch is mounted in the far end of the heat exchanger assembly the end which is farthest from the operator control panel You should be able to reach this switch from the top of the unit Remove the top panels so you can see the switch 3 Unplug the wiring connector four wires The connector is locked in place by a squeeze tab Press on t...

Page 58: ...ng or is disconnected the display will present three dashes To check the sensor for accuracy see Section B32 The DHW sensor is mounted in the indirect hot water tank and provides the input for the DHW Domestic Hot Water function This type of sensor can fail in either an open or shorted condition or may become inaccurate On a unit with the current user interface Check the line on the display for DH...

Page 59: ...ure 1 Turn off power to the system Use the main disconnect switch mounted above the front panel 2 Isolate the boiler Turn off the water shutoff valves located upstream and downstream of the unit 3 Drain the boiler The drain valve is located near the lower end of the heat exchanger 4 The inlet water temperature sensor is mounted in the shoulder of the heat exchanger assembly just above the point wh...

Page 60: ...For instructions on testing the assembly see Section B32 To reset the control system after the outlet sensor trips On a unit with the original white user interface Press the Reset button near the lower left hand corner of the display This will reset the lockout and the lockout code will disappear On a unit with current user interface Reset by pressing the OK button Removing and Replacing the Outle...

Page 61: ...temperature high limit duplex sensor Stack sensor duplex sensor There are up to three more sensors mounted at remote locations System sensor DHW sensor if installed Sensor for Outdoor Reset function if installed Each duplex sensor assembly actually uses two thermistors The con trol module compares the readings of the two If the difference becomes greater than allowed the controller declares a lock...

Page 62: ...cuit breaker to trip Yes Unit starts running Reconnect the sensor lead Is Outdoor Reset enabled on the controller Check programming Example Low boiler temp set to 130 heat setpoint set to 120 so unit never fires Example High and low boiler temps set the same so unit never fires The high temp setting must always be higher than the low temp setting Disconnect one lead from outdoor temperature sensor...

Page 63: ...does not trip you can check for normal voltages 120V AC input Black wire on TB1 120V hot to white wire on TB2 neutral 24V AC output Blue wire on TB3 24V hot to yellow wire on TB4 common If the meter indicates 120V input but there is no 24V output this indicates a bad transformer If there is no 24V AC output the operator display will not light up Replacement Procedure 1 Turn off the power to the NT...

Page 64: ... mounted on a pipe that extends up a few inches above the top panel of the NT unit 4 Disassemble and remove the drain pipe 5 Unscrew the valve from the vertical pipe using the two pipe wrenches 6 The replacement valve must be the correct size and capacity to match the size of the NT unit Check the old valve for two important numbers The capacity of the old valve listed in BTU The relief pressure o...

Page 65: ... 120V power supply to the unit 2 Turn off all manual gas valves connecting the unit to the main gas supply line 3 Remove the front door of the unit to gain access to the ignitor assembly 4 Remove the two wires connected to the assem bly 5 Remove the two bolts connecting the ignitor assembly to the burner door Remove the old ignitor assembly 6 Install a new assembly by reversing the instruc tions l...

Page 66: ...e 4 The end of the flame rod should be 1 4 away from the burner See Fig B36 2 Cleaning or Replacement Procedure 1 Shut off the 120V power supply to the unit 2 Turn off all manual gas valves connecting the unit to the main gas supply line 3 Remove the front door of the unit to gain access to the flame sensor electrode 4 The best way to clean the flame sensor is to use a dollar bill as shown in Fig ...

Page 67: ...t Control Input if the safety chain includes a flow switch The SOLA controller also can display error 51 Pump Fault No No Check for 120V at terminals 1 and 2 on TB5 Pump is getting power Disassemble and or replace pump Pump sounds different No Yes Pump is moving water No Replace pump Pump is running Yes Yes Disassemble and or replace pump B38 Pump Fault ...

Page 68: ...58 Service Manual NeoTherm 500 ...

Page 69: ...ith the gas and the flame produces CO2 carbon di oxide and H2 O water Carbon di oxide includes two oxygen atoms attached to every carbon atom When the burner cannot get enough air the flame is starved for air The flame continues to burn but since enough oxygen is not available the result is CO carbon mon oxide Carbon mon oxide includes just one oxygen atom attached to each carbon atom This is dang...

Page 70: ...e Next button several times until you see Rate and 100 Press the Up arrow The NT unit is now forced into high fire for 5 minutes The CO2 readings should be between the values shown in Table C2 1 If the CO2 is not within the range shown adjustments may be made To adjust the high fire CO2 locate the high fire adjuster screw as shown in Fig C2 1 Slowly make adjustments in 1 16 of a revolution increme...

Page 71: ...he CO2 is within the range identified For the low fire adjustment turning the screw clockwise CW makes the mixture richer 3 Repeat steps 2 and 3 to confirm that the CO2 readings are within the re quired ranges Adjust each setting again if necessary 4 Confirm that the differential pressure is still within the appropriate range 5 If any of the measurements cannot be adjusted to the specified ranges ...

Page 72: ...igh fire for 5 minutes then return to normal operation How to get there From the Home screen press I to go to Info Install Choose Test then go to Forced Rate Select Set High Fire then select Start Test The CO2 readings should be between the values shown in Table C3 1 If the CO2 is not within the cor rect range adjust the high fire setting See Fig C3 1 to locate the high fire adjuster screw Slowly ...

Page 73: ... makes the mixture richer 3 You might have to go back and forth between high fire and low fire several times before the CO2 readings are correct in both cases Repeat steps 2 and 3 and continue to adjust until the CO2 readings are stable 4 Check to see that the differential pressure is still within the correct range 5 If any of the measurements cannot be adjusted to the specified ranges or the CO l...

Page 74: ... figures in Table Cannot reach Gas inlet pressure OK Yes No Gas supply problem Check with gas company Interior of burner is clean No Clean burner and heat exchanger See Section C5 Can reach Combustion is OK Replace gas valve Any gas leaks inside the unit No Check all hoses tighten all connections Yes C4 ...

Page 75: ...hanger Because of the way the air gas channel is attached to the blower the simplest way to do this is to remove the whole air gas chan nel blower gas valve assembly This will require you to disconnect the gas inlet first Figure C5 1 shows how the parts are arranged Fig C5 1 Front of heat exchanger and other part Tools and equipment required Disassembly Reassembly Socket wrench with 10 mm and 13 m...

Page 76: ...sembly to the blower See Fig C5 3 The 5 16 socket will fit the head of each bolt Use the 3 8 socket on the nut on the other end 5 Behind the gas valve locate the black rubber air intake hose Loosen the hose clamp on the left end of this hose and pull the end of the hose away from the end of the Venturi Fig C5 4 shows how the unit will look when you have finished this step Fig C5 2 Gas shutoff valv...

Page 77: ...changer from the rest of the unit See Fig C5 6 Note the two large wires running to this as sembly The spark wire and the flame sense wire look alike The unit will not run if you reverse these wires Before removing the wires mark the spark wire with a piece of electrical tape Also dis connect the green ground wire Ground wire green Spark wire mark with electrical tape Flame sense wire Power Control...

Page 78: ... every time you clean the unit or remove the front cover of the heat exchanger 9 Fig C5 8 shows how the assembly looks after it has been removed Note The white ceramic refractory material on the inside of the heat exchanger front plate is brittle and can be damaged easily Handle the heat exchanger front plate carefully Remove these nuts Fig C5 7 Removing the front of the heat exchanger Burner Fron...

Page 79: ...ower Shown with front cover for heat exchanger removed Cleaning the Burner and Heat Exchanger continued C5 cont 12 Now you can pull the burner out of the hole in the front plate for the heat exchanger Normally you will see some soot or dust on the thin metal vanes on the outside of the can Blow any soot or dust off of the vanes using compressed air 50 psi max Wipe out the inside of the can with a ...

Page 80: ...ve the protective coating The sensor will work but only for a short time The best way to clean the flame sensor is to use a dollar bill as shown in Fig C5 10 The paper used in the bill is just abrasive enough to clean the sensor correctly without removing the protective coating 2 Figure C5 11 shows the inside of the heat exchanger Black carbon soot can build up on the coils as a result of poor com...

Page 81: ...l Stainless steel coils dirty C5 cont The heat exchanger in Fig C5 11 is new so it is clean Figure C5 12 is a photo of a dirty heat exchanger Normally you will find a heat exchanger that looks like this However sometimes a heat ex changer can be really dirty as shown in Fig C5 13 3 Attach one end of the drain hose to the condensate drain located under the heat exchanger Run the other end of the ho...

Page 82: ...ang er tighten the nuts in a cross pattern See Fig C5 16 If you tighten all of the nuts on one side first this might bend or distort the cover 4 The gas valve includes a rubber washer See Fig C5 17 Be sure to insert this in the correct position when replacing the valve 5 The gas valve has an On Off switch When replac ing the valve be sure this is set to On 6 When re attaching the gas inlet remembe...

Page 83: ...n produced with two different types of user interfaces as shown below Notice that Laars has been using the same control module through out the SOLA controller but the user interfaces were changed in 2012 There were actually two versions of the current user interface issued before and after Octo ber 2012 There are slight differences in the way these two versions operate The type of interface used o...

Page 84: ...ed Table D2 1 User Mode Menu Structure The interface records the last lockout and alert codes but these are erased if the interface is reset or power to the NeoTherm unit is turned off We will explain how to handle lockouts on this interface in Section D3 Whenever you change a setpoint or value you must press the Done button If you do not do this the in terface will continue to use the old setpoin...

Page 85: ...t cycle minutes of delay between startups Table D2 2 Setup Mode Parameters Using the Original White User Interface continued Diagnostic Menu Diagnostic Mode allows you to see any alerts or lock outs This mode is also used to set up the high fire and low fire conditions so you can do the gas valve CO2 adjustment To go to the Diagnostic Mode press and hold the Next button for three seconds The displ...

Page 86: ...arily indicate a problem Here is the procedure used to recover from a Lockout The Lockout indication will appear in the lower left hand corner of the dis play and the lockout code will flash in the center Write down the lockout code and look it up in the Appendix at the end of this manual Press the Reset button near the lower left hand corner of the display This will reset the lockout and the lock...

Page 87: ...el 3 Disconnect all of the wiring connections to the control module The connectors are keyed so that they can only be inserted one way Be careful not to bend the wires sharply or pull them out of the connectors 4 To remove the user interface push in on the two tabs on the left side of the board to unlatch the clips from the control panel Rotate the board around the fastening points on the right si...

Page 88: ...ol ler Up Down Arrow buttons Use these to go to the choice you want to select in the display area then press the round OK button Left Right Arrow buttons Use these to go to the choice you want to select in the display area then press the round OK button Back button Use this to go back to the previous display Info Install button Press this button at any time to go to the sub menus that allow you to...

Page 89: ...on your system The central section shows some additional operating and setup information In this case this area lists the boiler name boiler state current demand and the current password level the access status The lower section shows any current lockouts holds or alerts Info Install Display From the Home display shown in Fig D5 2 press the I button Info Install The display will change to show the...

Page 90: ...f lockouts and alarms Display Setup You can use this option to adjust the contrast of the display or change the items which appear at the top of the Home display Table D5 2 Functions on Info Install Menu Changing a Value The procedure for changing a control value used by the system is listed below In this example we will use the screen for the CH Setpoint Use the Up and Down Arrow buttons to step ...

Page 91: ... is 1 min ute The numbers near the left edge of the screen show the allowable range for this value In this case the time can be set anywhere between 1 minute and 15 minutes In this example we will change the time delay to 5 min utes Press the Left and Right Arrow buttons to move to the box you want In this case we want to change the middle box the box for Minutes Use the Up and Down Arrow buttons ...

Page 92: ...y be changed by a trained techni cian who enters a password These include setup and parameter changes made when the system is installed and some diagnostic and troubleshooting functions The installer level password is lnt lower case LNT OEM Level Some of the settings can only be changed at the Laars factory Once you enter a password the password access remains valid until you exit to the normal no...

Page 93: ... Diagnostics to check the status of the sensors and the digital inputs and outputs The system also records a history of lockouts and alarms Analog Sensors You can use this display to check on operating temperatures fan speed firing rate etc The word analog refers to values that can change continu ously between zero and a higher value The values shown here are Read Only you can t change them from t...

Page 94: ...rrect delayed or waiting for a response This does not necessarily indicate a problem If a problem occurs while the system is starting up the system will declare a Hold A brief explanation of the cause of the Hold will appear in a line across the bottom of the screen If a serious problem continues the system will declare a Lockout A brief explanation of the cause of the Lockout will appear in a lin...

Page 95: ...e connected Swing the panel up and place it face down on the cloth Ribbon cable connectors X01 12 pin X07 8 pin 4 Disconnect the two wiring connectors 8 pin connector X07 12 pin connector X01 Each connector is held in place by a locking tab To release the connector push the tab down 5 Disconnect the two ribbon cable connectors 6 Remove the four Phillips head screws and separate the user interface ...

Page 96: ...Therm unit because the Honeywell SOLA control ler is the most complicated part it s tempting to assume that the controller is causing the problem Usually the problem is caused by an input a sensor or switch or by a programming problem Don t automatically assume that every problem is caused by a bad controller Laars uses the same SOLA controller in many different NeoTherm models The controllers are...

Page 97: ...rd all of the existing control settings if pos sible This will allow you to re enter the settings after you install the new controller Record the current settings for temperature set points outdoor reset and lead lag 2 Turn off power to the system Use the main disconnect switch mounted above the front panel 3 Remove the front panel from the unit by pulling it straight out 4 Disconnect the wires an...

Page 98: ...remove the control push the lower ends of the left side clips and swing the left side of the control toward you Green connector mounted in far right position J2 J1 CP10 J10 CP9 J9 CP8A J8 CP8B J8 J6 CP6 J5 CP5 J4 CP4A J4 CP4B Spark cable Removing and Replacing the SOLA Controller continued Fig D9 2 Connectors on the SOLA controller 6 Mount the new controller using the four clips 7 Replace the wire...

Page 99: ...ration mode and safety parameters need verification and a device needs reset to complete verification 2 Configuration ended without verification re enter configuration verify safety parameters and reset device to complete verification 3 If fault repeats replace module 3 Internal fault Hardware fault H Internal fault 1 Reset module 2 If fault repeats replace module 4 Internal fault Safety relay key...

Page 100: ...L Internal fault 1 Reset module 2 If fault repeats replace module 18 Internal fault Safety relay test failed due to feedback not on L Internal fault 1 Reset module 2 If fault repeats replace module 19 Internal fault Safety RAM write L Internal fault 1 Reset module 2 If fault repeats replace module 20 Internal fault Flame ripple and overflow H Internal fault 1 Reset module 2 If fault repeats replac...

Page 101: ...ault repeats replace module 32 46 Internal fault Safety key 0 through 14 L Internal fault 1 Reset module 2 If fault repeats replace module 47 Flame rod to ground leakage H Check flame rod See Section B37 Internal fault in SOLA controller Internal fault 1 Reset module 2 If fault repeats replace module 48 Static flame not flickering H Internal fault 1 Reset module 2 If fault repeats replace module 4...

Page 102: ...lace the module 64 PII Pre Ignition Interlock off H or L 1 Check wiring and correct any faults 2 Check preignition interlock switches to assure proper functioning 3 Check the valve operation 4 Reset and sequence the module monitor the PII status 5 If code persists replace the module 67 ILK Interlock off H or L 1 Check wiring and correct any possible shorts 2 Check Interlock ILK switches to assure ...

Page 103: ...or fault H 1 Check wiring and correct any possible errors See Section B28 2 Replace the Inlet sensor 3 If previous steps are correct and fault persists re place the module 92 Outlet sensor fault H 1 Check wiring and correct any possible errors See Section B30 2 Replace the outlet sensor 3 If previous steps are correct and fault persists re place the module 93 DHW Domestic Hot Water sensor fault H ...

Page 104: ...any errors 2 Make sure that the flame detector is wired to the cor rect terminal 3 Make sure the flame and ground wires are protected from stray noise pickup 4 Reset and sequence the module if code reappears replace the flame detector 5 Reset and sequence the module if code reappears replace the module 106 Flame lost in MFEP Main Flame Establish ing Period L 1 Check main valve wiring and operation...

Page 105: ...nal hardware test Not a lockout 111 Flame current lower than weak threshold H Hold time of recycle and hold option Will not be a lockout fault Hold only Internal hardware test Not a lockout 113 Flame circuit timeout L Flame sensed during initiate or off cycle hold 240 sec onds if present after 240 seconds system will lockout 119 Control Interaction fault H Flap valve identifications configured inc...

Page 106: ...the VFD s Variable speed Fan Drive ability to change speeds 3 Change the VFD 4 If the fault persists replace the module 137 ILK Interlock failed to close H 1 Check wiring and correct any possible shorts 2 Check interlock ILK switches to assure proper func tion 3 Verify voltage through the interlock string to the inter lock input with a voltmeter 4 If steps 1 3 are correct and the fault persists re...

Page 107: ...an switch J6 terminal 3 and its connections Make sure the switch is working correctly and is not jumpered or welded 4 Reset and sequence the relay module 5 If the fault persists replace the relay module 156 Combustion pressure and flame on H or L 1 Check that flame is not present in the combustion chamber Correct any errors 2 Make sure that the flame detector is wired to the cor rect terminal 3 Ma...

Page 108: ...oltage across the switch Supply voltage should be present If not the block intake switch is defective and needs replacing 5 If the fault persists replace the relay module 165 Block intake off L 1 Check wiring and correct any errors 2 Inspect the block intake switch to make sure it is working correctly 3 Reset and sequence the module 4 During standby and purge measure the voltage across the switch ...

Page 109: ...ponse setting L 1 Return to configuration mode and recheck selected parameters reverify and reset module 2 If fault repeats verify electrical grounding 3 If fault repeats replace module 189 Invalid flame sensor type setting L 1 Return to configuration mode and recheck selected parameters reverify and reset module 2 If fault repeats verify electrical grounding 3 If fault repeats replace module 192 ...

Page 110: ...ule 201 Invalid lightoff rate proving setting L 1 Return to configuration mode and recheck selected parameters reverify and reset module 2 If fault repeats verify electrical grounding 3 If fault repeats replace module 202 Invalid MFEP Main Flame Establishing Period time setting L 1 Return to configuration mode and recheck selected parameters reverify and reset module 2 If fault repeats verify elec...

Page 111: ...epeats replace module 215 Invalid purge rate proving setting L 1 Return to configuration mode and recheck selected parameters reverify and reset module 2 If fault repeats verify electrical grounding 3 If fault repeats replace module 216 Invalid run flame failure response setting L 1 Return to configuration mode and recheck selected parameters reverify and reset module 2 If fault repeats verify ele...

Page 112: ...rical grounding 3 If fault repeats replace module 226 Invalid outlet high limit setpoint setting L 1 Return to configuration mode and recheck selected parameters reverify and reset module 2 If fault repeats verify electrical grounding 3 If fault repeats replace module 227 Invalid DHW Domestic Hot Water high limit setpoint setting L 1 Return to configuration mode and recheck selected parameters rev...

Page 113: ...nd recheck selected parameters reverify and reset module 2 If fault repeats verify electrical grounding 3 If fault repeats replace module 237 Invalid DHW Domestic Hot Water connec tor type setting L 1 Return to configuration mode and recheck selected parameters reverify and reset module 2 If fault repeats verify electrical grounding 3 If fault repeats replace module 238 Invalid stack connector typ...

Page 114: ...ermittent spark can be seen 6 The controller waits through a trial for ignition period of four seconds The direct spark ignition switches to constant spark for three sec onds during which time the gas valve is open For the last second of the ignition period direct spark is de energized and the flame sensor checks for established flame If a flame is sensed the control enters Run to satisfy the dema...

Page 115: ...105 Service Manual NeoTherm 500 Appendix 3 Wiring Diagram App3 ...

Page 116: ...106 Service Manual NeoTherm 500 ...

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Page 118: ...Fax 800 559 1583 Headquarters 20 Industrial Way Rochester NH 03867 603 335 6300 Fax 603 335 3355 1869 Sismet Road Mississauga Ontario Canada L4W 1W8 905 238 0100 Fax 905 366 0130 www Laars com Litho in U S A Laars Heating Systems 1407 Document 1292 HLW ...

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