Laars NeoTherm NTV Service Manual
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Laars NeoTherm NTV Service Manual

Modulating boiler sizes 399-850 mbtu/h, water heater sizes 399-850 mbtu/h
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See also: User Information
Service Manual
for
N
EO
T
HERM
®
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
N
EO
Document 1292
T
HERM

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Summary of Contents for Laars NeoTherm NTV

  • Page 1 Document 1292 Service Manual HERM ® 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 HERM...
  • Page 3 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 can’t diagnose the problem using the information in this manual: LAARS Product Support...
  • Page 4 Finding Information in this PDF File This manual includes a lot of detailed information, but none of this is very useful to you unless you can find it. We’d like to help you to find the information you need, quickly and easily. There are four ways to locate information in this PDF* file.

  • Page 5: Safety Notes

    Safety Notes Please read this section before beginning any troubleshooting procedures. If the information in this manual is not followed exactly, a fire or ex- plosion may result, causing loss of life, personal injury, or property damage. Necessary Training - This product must be installed and serviced by a professional service technician, qualified and/or licensed in hot water boiler and heater instal- lation and maintenance.
  • Page 6 Electrical Shock Hazard Electrical shock can cause severe injury, death or property damage. Only a professional technician, trained in electrical safety, should work on this unit. Whenever the troubleshooting procedures make this possible, turn off the power to the unit before working inside the cabinet. The only exceptions would be when it is necessary to test the voltages between the points listed in this manual.

  • Page 7: Table Of Contents

    Table of Contents Section A - Troubleshooting - Start Here Sect. Title ................Page Troubleshooting - Start Here ..........1 Unit Will Not Fire - Blower is Not Running ......2 Blower Runs Continuously, No Display ....... 4 Control Unit is in “Standby” Mode ........5 Changing Control Settings, Change Not Complete - Unit with Original (White) User Interface ......
  • Page 8 Table of Contents (continued) Removing and Replacing the High and Low Gas Pressure Switches ............. 32 Checking the Condensate Trap Water Level Switch ..35 Testing the Condensate Trap Level Switch ....... 36 Removing and Replacing the Condensate Trap ....36 Checking the Air Pressure Switch - Blower Proving Switch ............
  • Page 9 Table of Contents (continued) Section C - Possible Combustion Problems Sect. Title Page About Correct Combustion ..........59 Combustion Adjustment Procedure - Units with Original (White) User Interface ......60 Combustion Adjustment Procedure - Units with Current User Interface ........62 Troubleshooting Combustion Problems ......
  • Page 10 viii Service Manual - NeoTherm 500...

  • Page 11: Troubleshooting - Start Here

    Troubleshooting - Start Here Is this a new See “Quick Check of Components installation? New installation, in the Safety Chain and Did the unit ever never ran correctly Firing Sequence” - Section B1 run correctly? Old installation, ran correctly What changed? Operating conditions? Did you change any control settings? For troubleshooting instructions, see these sections:...

  • Page 12: Unit Will Not Fire - Blower Is Not Running

    Unit Will Not Fire - Blower is Not Running Check 120V AC electrical power. Display is lit? See Section B2 - “Troubleshooting the 24V AC Power Supply” Short contacts: Central Heat: 5-6 on TB7 DHW: 5-6 on TB6 Has call for heat? Original user interface shows: Check, Pre-Purge, Run = Normal operation Current user interface shows:...
  • Page 13 Unit Will Not Fire - Blower is Not Running cont. Incoming gas Adjust regulator. pressure is Check with gas company. See table of code numbers Problem indication Yes - Code number in Appendix. from controller? supplied Controller stuck in See Section A4 “Control Unit is in Standby Mode”...

  • Page 14: Blower Runs Continuously, No Display

    Blower Runs Continuously, No Display In this condition, the blower is running continuously, but the display is completely blank. Reset 24V breaker If unit continues to operate normally - switch under trans- temporary condition former. Resets? If breaker trips again - See Section B2 Check the 24V power supply.

  • Page 15: Control Unit Is In "Standby" Mode

    Control Unit is in “Standby” Mode In certain situations, the controller on this unit can go into “Standby” In certain situations, the controller on this unit can go into mode. The Boiler pump is running, so the unit sees a “Call for heat.” “Standby”...

  • Page 16: A4 Control Unit Is In "Standby" Mode

    Control Unit is in “Standby” Mode (continued) cont. Example: Controller reacting High flue temperature trips to a temporary problem? High Stack Temp. Sensor. Unit will not run for 20 min., then automatically resets. Were you changing Units with original (white) user interface - the control settings? See Section A5 “Changing Control Settings,...

  • Page 17: A5 Changing Control Settings, Change Not Complete

    Changing Control Settings, Change Not Complete Original (White) Interface NeoTherm units were produced using two types of user interfaces. (See Section D1 to identify the kind of interface used on your unit.) These instructions apply to units with the original (white) user interface. In certain situations, the controller used in this unit can go into a “Stand- by”...

  • Page 18: Unit Is Running, But Building Is Still Cold

    Unit is Running, But Building is Still Cold Air inlet is Clear it blocked? Air intake inside unit is Clean plugged? Dirty fan? Clean, blow out (Gas/air mixture is correct, but not enough gas/air mixture is supplied.) Burner and/or heat exchanger plugged? See “Cleaning the Burner and Heat Exchanger”...

  • Page 19: Control Unit Says "Run", But Boiler Is Not Firing

    Control Unit Says “Run,” But Boiler is Not Firing In this condition, the panel is lighted, so you know the unit has power. The Boiler pump is running, so you know the unit is receiving the call for heat. The blower is running, the unit has spark, and the gas valve is operating correctly.

  • Page 20: A9 Unit Runs In High Or Low Fire Only

    Unit Runs in High or Low Fire Only 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”...

  • Page 21: Quick Check Of Components In The Safety Chain

    DANGER! - When the cover is opened, some of the areas carrying 120V AC voltage will not be covered. Do not perform the following tests unless you have been trained how to do this safely by Laars. 1. Remove the front panel assembly and front bezel.

  • Page 22: B1 Quick Check Of Components In The Safety Chain

    Quick Check of Components in the Safety Chain - continued cont. 6. If this unit is set up to use a separate DHW signal – Insert a jumper across terminals 5 and 6 on TB-6 on the control board. See Fig. B1-3. This will create a BOILER PUMP permanent “Call for DHW”...
  • Page 23 Quick Check of Components in the Safety Chain - continued cont. 10. Check for 24V AC between terminal J6-1 on the control module and any terminal on TB4. See Fig. B1-6. If 24V AC is present here, this means that the following safety switches are OK: •...
  • Page 24 Quick Check of Components in the Safety Chain - continued cont. 12. If the unit is receiving a “call for heat,” and all of the safety switches are OK, the blower should be receiv- ing control voltage through J2 on the control module. See Fig.

  • Page 25: Troubleshooting The 24V Ac Power Supply

    Troubleshooting the 24V AC Power Supply 24V AC between TB3 24V AC supply is OK and TB4? Reset 24V AC supply is OK circuit bkr. on Why did breaker trip? transformer Loose or damaged wire? 24V OK now? Check Disconnect power. for bad Check transformer - see Section B34.

  • Page 26: B3 Checking The Safety Interlocks

    Checking the Safety Chain Check for 24V AC between TB8-1 and TB4-1. 24V AC is present? Safety chain is OK (all switches closed) Check for 24V AC between TB8-2 and TB4-1. See procedure B4 - 24V AC is “Checking the Low Water Cutoff Switch” present? Check for 24V AC between TB8-3 and TB4-1.
  • Page 27 Checking the Safety Chain - continued cont. Check for 24V AC at terminal J6-1. 24V AC is present? See procedure B16 - (other safety “Checking Condensate Trap Level Switch” switches closed) With boiler attempting to run, check for 24V AC across two leads on air pressure switch.

  • Page 28: Checking The Low Water Cutoff Switch

    Checking the Low Water Cutoff Switch (option) Check for water in boiler? Check water supply, water pressure, Water present? and auto makeup valve. Reset low water cutoff control Control resets? OK - temporary condition Are you using ultra-pure water? Ultra-pure water will not conduct Ultra-pure water? electrical current = false low water reading Check for continuity from...

  • Page 29: Controller For Low Water Cutoff

    Checking the Low Water Cutoff Switch (continued) cont. Check for dirty probe. The system may have tripped Probe dirty? because of small air bubbles. Wipe down the probe. (Do this once a year.) System recently Drain and flush the system. installed? Controller for Low Water Cutoff The low water cutoff switch operates by passing...

  • Page 30: B6 Removing And Replacing The Low Water Cutoff Switch

    Removing and Replacing the Low Water Cutoff Controls The low water cutoff (LWCO) is designed to shut down the unit if there is a low water condition. The control includes two parts: a control box, and a probe which reaches into the water piping. Tools and equipment required: •...
  • Page 31 Removing and Replacing the Low Water Cutoff Controls (cont.) cont. Procedure - Replacing the control box 1. To remove the cover, remove the two sheet metal screws on the sides. P2 - Black with orange stripe 2. Disconnect the three wires on the terminal strip, P1 - Brown with yellow stripe and the violet wire that runs to the connector above the terminal strip.

  • Page 32: High Water Temperature Limit Switch

    High Water Temperature Limit Switch (optional) Laars does not provide this switch. It is installed only where required. This is a normally-closed (NC) switch. If the water temperature rises above the pre-set limit, the switch opens. Some types of switches must be reset manually. To reset this type of switch, press the button on the control.

  • Page 33: Testing The Flow Switch

    Testing the Flow Switch The flow switch uses a set of paddles to sense water flowing through the system. See Fig. B9-2. When water is flowing, the switch is normally closed (N.C.). If the water flow stops, the switch opens. After a “no flow”...

  • Page 34: Removing And Replacing The Flow Switch

    Removing and Replacing the Flow Switch The switch assembly includes two parts: a set of paddles that extend into the water pipe, and a control box. See Fig. B9-1. Figure B9-2 shows the paddles that extend into the piping to detect the water flow.
  • Page 35 Removing and Replacing the Flow Switch (continued) cont. 7. Once you have trimmed the paddles, install them on the switch. See Fig. B10-1. Insert the pin to Paddles attach the paddles to the center post. 8. Important! When the switch is installed, the ends of the paddles must sit in the correct orientation inside the pipe.

  • Page 36: Removing And Replacing The Gas Valve

    Removing and Replacing the Gas Valve The modulating gas valve consists of a valve body that controls the on/off gas flow and a negative pressure regulator. It provides the air/gas ratio control in combination with the Venturi to the unit. The easiest way to remove the gas valve is to remove a section of the gas input piping, including the gas valve and the high gas pressure switch.
  • Page 37 Removing and Replacing the Gas Valve (continued) cont. 5. Disconnect the small vacuum hose running to the Wire to N.C. contact top of the gas valve. 6. Disconnect the wires to the high gas pressure switch only. (On the unit, this is the pressure switch on the left, on the side closest to the blower.
  • Page 38 Removing and Replacing the Gas Valve (continued) cont. 9. Now you can remove the whole assembly from It is safe to Be careful not grip the valve to crush this the machine. Figure B11-6 shows the complete across this part cover.

  • Page 39: Checking The High Gas Pressure Switch

    Checking the High Gas Pressure Switch The high gas pressure switch is a 24V manual reset switch that acts to cut power to the gas valve if the gas pressure is too high for proper op- eration. The type of switch used is integrally vent limited, and does not require venting to the atmosphere.

  • Page 40: Checking The Low Gas Pressure Switch

    Checking the Low Gas Pressure Switch The low gas pressure switch is a 24V manual reset switch that acts to cut power to the gas valve if the gas pressure is too low for proper operation. The type of switch used is integrally vent limited, and does not require venting to the atmosphere.

  • Page 41: Testing The Low Gas Pressure Switch

    Testing the Low Gas Pressure Switch In the gas train, this switch is located before the gas control valve. Gas will reach this switch whenever the gas shutoff valve to the unit is open. Figure B14-1 shows the gas train. Connect a test gauge to the inlet gas pressure tap.

  • Page 42: B15

    Removing and Replacing the High and Low Gas Pressure Switches Each NT unit includes two switches which sense gas pressure: Gas valve Low gas pressure • The low gas pressure switch is located before switch the gas valve. It will prevent the unit from firing if there is not enough gas pressure to operate cor- rectly.
  • Page 43 Removing and Replacing the High and Low Gas Pressure Switches (continued) cont. Procedure - Removing or replacing either switch 1. Turn off power to the machine. Use the main discon- nect switch on the front of the machine, just above the control panel.
  • Page 44 Removing and Replacing the High and Low Gas Pressure Switches (continued) cont. For the low gas pressure switch only - Mark the wire on the left using a piece of electri- cal tape. When the switch is assembled, this wire will go to the “N.O.” connection. Set to 3”...

  • Page 45: Checking The Condensate Trap Water Level Switch

    Checking the Condensate Trap Level Switch Check for 24V AC across switch. 24V AC present? See Section B3 - (switch open) “Checking the Safety Chain” Check for blocked or frozen condensate outlet. Test switch. See Section B17. Outlet blocked? Replace if necessary. See Section B18.

  • Page 46: Testing The Condensate Trap Level Switch

    Testing the Condensate Trap Level Switch Some operating conditions can cause small particles of mineral material to be formed in the heat exchang- er and collect in the condensate trap. The drain can also be blocked if it is frozen or plugged with debris. Set- If the water cannot drain freely, it can back up into screw...
  • Page 47 Removing and Replacing the Condensate Trap (continued) cont. Tools and equipment required: 1/4” socket • Small diagonal cutters or knife • Water-pump pliers • 11” Ty-wrap Procedure 1. Turn off power to the system. Use the main disconnect switch mounted above the front panel. 2.

  • Page 48: B19

    Checking the Air Pressure Switch - Blower Proving Switch Check for blocked air intake and exhaust vents. Exhaust vent Clear the vents. blocked? Check the bird screens or terminals. Dirty fan? Clean with a shop-vac. Test the air pressure switch. (See Section B20.) Switch is OK? Replace switch.

  • Page 49: Test Procedure For Air Pressure Switch

    Test Procedure for Air Pressure Switch 1. The switch is located behind the front panel. Dis- connect the two leads, and connect a Volt-Ohmme- ter set to check for continuity (reading Ohms). 2. Insert a hose “T” in the clear plastic hose that runs to the positive pressure port (closest to the electrical connections).

  • Page 50: B21 Removing And Replacing The Air Pressure Switch

    Removing and Replacing the Air Pressure Switch (continued) cont. Procedure - Removing or replacing the switch 1. Turn off power to the machine. Use the main disconnect switch located above the top of the control panel. 2. Remove the covers on top of the unit so you can reach the air pressure switch.

  • Page 51: Checking The Blower

    Checking the Blower At start of test, unit should be ready to run (”Standby”) Has call for heat? Short contacts Problem with temp. sensor(s) for call for heat: System sensor - Section B26 Blower runs CH: TB7 5-6 DHW sensor - Section B27 DHW: TB6 5-6 Blower does not run Unplug J2.

  • Page 52: Removing And Replacing The Blower

    Removing and Replacing the Blower The easiest way to remove the blower is to remove it as part of an assembly, including the air/gas chan- nel, front panel of the combustion chamber, and the burner. Once you have done this, you can separate the burner from the rest of the assembly.
  • Page 53 Removing and Replacing the Blower (continued) cont. 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. When you have finished this step, the unit will look like Fig.
  • Page 54 Removing and Replacing the Blower (continued) cont. 8. Now you can remove the front of the heat exchanger, with the blower and burner still at- tached. Undo the six 10mm nuts around the out- Remove side of the front plate of the heat exchanger. See these Fig.
  • Page 55 Removing and Replacing the Blower (continued) cont. 11. The location where you removed the Venturi is the air intake for the blower. To clean the blower, blow compressed air through the intake and spin the impeller. 12. To reassemble, reverse the procedure listed above. Fig.

  • Page 56: High Stack Temperature Fault

    High Stack Temperature Fault Actual stack Correct this immediately. temperature Blocked exhaust outlet? problem? Dirty heat exchanger? If you have the current user interface, set the stack temperature limit to 190°F. Problem with circulator See Section B38. pump? Check the continuity on the wires from Wiring to sensor is correct? Good the sensor to J9-4, J9-5, and J9-6 on the...

  • Page 57: B25

    Removing and Replacing the Stack Temperature Limit Switch The stack temperature limit switch will shut down the NT unit if the stack temperature rises above 195°F. This is a “duplex” sensor - it actually includes two separate thermistors. The control system constantly compares the readings from the thermistors.

  • Page 58: Checking The System Sensor

    Checking the System Sensor The System sensor is mounted in the circulating loop, and provides the input for the CH (Central Heating) 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 “LL OPER TEMP.”...

  • Page 59: Inlet Water Temperature Sensor

    Inlet Water Temperature Sensor A typical installation for the inlet water temperature sensor is shown in Fig. B28-1. The sensor is connected to J8 4-5 on the control module. This sensor uses an electronic device called a “thermistor.” For instructions Sensor on testing the sensor, see Section B32.

  • Page 60: Outlet Water Temperature Sensor

    Outlet Water Temperature Sensor The outlet water temperature switch allows the control system to monitor the temperature of the water as it leaves the NT unit. A typical installation for the outlet Sensor water temperature sensor is shown in Fig. B30-1. The sensor is connected to J8 8-9-10 on the control module.

  • Page 61: Testing The Temperature Sensors

    Removing and Replacing the Outlet Water Temperature Sensor (continued) cont. 4. The outlet water temperature sensor is mounted in the shoulder of the heat exchanger assembly, just above the point where the water outlet pipe is at- tached to the heat exchanger. (The outlet pipe is marked with a label on top of the unit.) Remove the top panels on the unit so you can reach the temperature sensor.

  • Page 62: Troubleshooting The Outdoor Reset System

    Troubleshooting the Outdoor Reset System Disconnect one lead from outdoor temperature sensor 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.
  • Page 63 Servicing the Transformer (continued) cont. Tools and equipment required: • Volt-Ohmmeter • Phillips head screwdriver (size #1) • Deep socket for transformer mounting nuts Test Procedure: It is simplest to test the transformer by checking the Reset voltages at other points on the NT unit. switch 1.

  • Page 64: Removing And Replacing The Pressure Relief Valve

    Removing and Replacing the Pressure Relief Valve Note - If the system pressure exceeds the relief valve setting, Normally a drain pipe the pressure relief valve is designed to open and release would run from here to the excess pressure and water. Note - This type of valve within 6”...

  • Page 65: Ignitor Assembly

    Ignitor Assembly The ignitor assembly is a two-rod system that con- sists of a ground rod and a spark rod. Adjustment 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.

  • Page 66: Flame Sensor

    Flame Sensor The flame sensor is a single-rod system, and is mounted in the front cover of the heat exchanger. Over time, this sensor can become tarnished or coated. (This will hap- pen more quickly if the NT unit has been operating often at a low firing rate.) The flame sensor has a protective coating.

  • Page 67: Pump Fault

    Pump Fault A problem with the circulator pump could appear as a #79 error (Outlet High Limit). It could also appear as a #63 error (LCI - Limit Control Input) if the safety chain includes a flow switch. The SOLA controller also can display error #51 - Pump Fault.
  • Page 68 Service Manual - NeoTherm 500...

  • Page 69: Section C - Possible Combustion Problems

    Possible Combustion Problems About Correct Combustion When the unit is firing, the gas valve must always supply the correct amount of gas to match the amount of air going through the burner. The ratio of gas to air remains con- stant, but the control module adjusts the blower speed to adjust for changes in heat load.

  • Page 70: Units With Original (White) User Interface

    Combustion Adjustment Procedure - Units with Original (White) User Interface WARNING Improper adjustment may lead to poor combustion quality, increasing the amount of carbon monoxide produced. Excessive carbon monox- ide levels may lead to personal injury or death. Equipment required: •...
  • Page 71 Combustion Adjustment Procedure - Units with Original (White) User Interface - continued cont. 2. Once you have completed the high fire combustion test, measure the CO in the flue products at Low Fire. How to get there: Use the Down arrow to set the “Rate” to “20%.” The NT unit is now forced to low fire for 5 minutes.

  • Page 72: Combustion Adjustment Procedure - Units With Current User Interface

    Combustion Adjustment Procedure - Units with Current User Interface WARNING Improper adjustment of the high fire and low fire settings may lead to poor combustion, increasing the amount of carbon monoxide produced. Excessive carbon monoxide levels may lead to personal injury or death.
  • Page 73 Combustion Adjustment Procedure - Units with Current User Interface (continued) cont. 2. Next, measure the CO and O in the flue products at low fire. The NeoTherm can be forced to remain in low fire during the setup. How to get there: From the “Home” screen, press “I” to go to “Info/ Install.” Choose “Test,”...

  • Page 74: Troubleshooting Combustion Problems

    Troubleshooting Combustion Problems During adjiustment, Combustion can reach target Can reach is OK. figures in Table? Cannot reach Gas inlet Gas supply problem. pressure OK? Check with gas company. Any gas leaks Check all hoses, inside the unit? tighten all connections. Interior of burner Clean burner and heat exchanger.

  • Page 75: Cleaning The Burner And Heat Exchanger

    Soot buildup or other debris on the heat exchanger may restrict the flue passages. Laars recommends the unit be inspected once a year, and cleaned if necessary. If a condensing boiler is operated consistently at high tem- peratures, it may need to be cleaned more often.

  • Page 76: C5 Cleaning The Burner And Heat Exchanger

    Cleaning the Burner and Heat Exchanger (continued) cont. Disassembly Procedure: 1. Turn off power to the machine. Use the main discon- nect switch on the front of the machine, just above the control panel. 2. Remove the front panel. 3. Shut off the gas at the gas shutoff valve on the right side of the machine (yellow handle).
  • Page 77 Cleaning the Burner and Heat Exchanger (continued) cont. 6. Disconnect the wires to the blower. See Fig. C5-5. Control There are two connectors. The power wires run to the front connector, and the control wires connect to the rear. 7. The next job is to separate the front plate on the heat exchanger from the rest of the unit.
  • Page 78 Cleaning the Burner and Heat Exchanger (continued) cont. 8. Now you can remove the front of the heat exchang- er, with the blower and burner still attached. Undo the six 10mm nuts around the outside of the front plate of the heat exchanger. See Fig. C5-7. As you Remove remove the part, note the position of the large black these...
  • Page 79 Cleaning the Burner and Heat Exchanger (continued) cont. 10. Separate the blower from the assembly by remov- ing the four 13mm screws. As you disassemble the parts, note the position of the black gasket. 11. Separate the air-gas channel from the front plate for the heat exchanger.
  • Page 80 Cleaning the Burner and Heat Exchanger (continued) cont. Cleaning Procedure: 1. The flame sensor is mounted in the front cover of the heat exchanger. Over time, this sensor can become tarnished or coated. (This will happen more quickly if the NT unit has been operating often at a low firing rate.) The flame sensor has a protective coating.
  • Page 81 Cleaning the Burner and Heat Exchanger (continued) cont. Stainless steel The heat exchanger in Fig. C5-11 is new, so it coils (dirty) is clean. Figure C5-12 is a photo of a dirty heat Refractory exchanger. Normally you will find a heat exchanger material that looks like this.
  • Page 82 Cleaning the Burner and Heat Exchanger (continued) cont. 4. Clean the heat exchanger by brushing away any soot with the toilet brush, and collecting the dust using a vacuum cleaner. Use the vacuum to remove any mineral granules. Caution! Do not use a stiff brush with wire bristles. This can scratch the tubes on the heat exchanger.

  • Page 83: Identifying The User Interface On Your Unit

    • The “user interface” - This is the control panel that allows the operator to change control settings and get readings from the unit. The user interface is mounted on the front of the unit. NeoTherm units have been 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 Fig. D1-1 changed in 2012. (There were actually two versions of Original (“white”) user interface - the current user interface, issued before and after Octo- 2012 and earlier ber 2012. There are slight differences in the way these two versions operate.) The type of interface used on your unit will affect the way you navigate between the different control functions. In...

  • Page 84: Using The Original (White) User Interface

    Using the Original (White) User Interface This interface was used on all NeoTherm models produced through 2012. There are a few features on this interface that you should know about - • When the NeoTherm unit is first turned on, the interface will go through a button self-test routine for 90 seconds. During this time, none of the buttons will work. Just wait for the self-test to be completed before you try to use the Down button interface. • 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 setpoint or value, and the unit may remain in “standby.” The display navigation is divided into three operating modes: User, Setup, and Diagnostic. User Menu Normally the unit will display the User mode screen shown Reset button Done button to the right. Notice the entry for Outlet in the upper left-hand Figure D2-1 - Typical display on original (white) corner. This means the interface is displaying the current user interface outlet temperature.
  • Page 85 Using the Original (White) User Interface - continued cont. Setup Menu To go to the Setup Mode, press and hold the Up and MENU ITEM DEFINITION Down buttons at the same time for about three seconds. F or C Selects temperature units The interface will indicate “°F.” LBTHODLOD Outdoor reset enable/disable - enables following menu items Press Next to go to the setup for Outdoor Reset (shown LBT Low boiler setpoint during outdoor reset as “LBT HOD LOD”). Use the Up button to turn on the HOD High outdoor temperature setpoint Outdoor Reset feature, if desired. Once this is enabled, LOD Low outdoor temperature setpoint press Next to go to the lines for Low Boiler Setpoint RMT Add Remote address - used for Lead/Lag setup (LBT), High Outdoor Temperature (HOD), and Low Out- Lead/Lag enable/disable - enables menu items door Temperature (LOD). To change any of these, use the Up and Down buttons. (You do not need to press Hysteresis - temp range between on/off cycles Done yet.) Base Load % - input rate before next boiler fires Warm weather shut-down temperature Use the Next button to step through the other items in ASC...

  • Page 86: Reacting To Lockouts On The Original (White) User Interface

    Reacting to Lockouts on the Original (White) User Interface The system responds to three kinds of trouble indications: • A ”lockout” is caused by a serious problem that might involve a safety issue. Once the controller enters a lockout, the burner will shut down, and will not be allowed to run again until the cause of the problem is corrected, and you reset the control system. • The system may enter a “hold” for a period of time before locking out. This allows the controller to see if the error is corrected before it goes to a hard lockout. • An “alert” indicates that some feature of the control system’s operation was not correct, delayed, or waiting for a response. This does not necessarily 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 lockout code will disappear. (This is why we told you to write it down.) If the problem condition is still present, the unit will lockout again. See Section A for troubleshooting instructions. You can also check the last lockout or alert code using the Diagnostic mode of the display: Press and hold the Next button until the display shows the flame signal followed...

  • Page 87: Removing And Replacing The Original (White) User Interface

    Removing and Replacing the Original (White) User Interface Please check the troubleshooting instructions in Section A before replacing the user interface. Here is the removal/ replacement procedure: 1. Turn off all power to the NeoTherm unit, and shut off all manual gas valves. 2. Remove the front door on the NeoTherm, and remove the plastic bezel from the control panel. 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 side to separate the hooks from the board. 5. To replace the part, repeat the steps listed above in the reverse order. Be sure to re-connect all of the wiring connectors in their proper locations. Service Manual - NeoTherm 500...

  • Page 88: Using The Current User Interface

    Using the Current User Interface This interface is used on all NeoTherm models produced since 2012. The table below lists the functions of the various parts of the user inter- face. In a moment, we will explain how to use the buttons to reach the different sections of the control system. Left/Right Up/Down Arrow Arrow buttons Display area buttons Back button Info/Install button Home button Round OK button Fig. D5-1 - Control buttons on current user interface Display area This area displays several different kinds of information, including current op- erating information, setup parameters, and messages from the SOLA control- 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.
  • Page 89 Using the Current User Interface - continued cont. Home Display When the boiler is operating normally, the controller will display the Home display. See Fig. D5-2. The screen display area has three sections: • The upper section of this screen displays the most important operating information for the unit. In the example shown here, the display is showing the sys- tem setpoint, the operating temperature, the outlet and inlet temperatures for the water entering and leaving the boiler, and the outdoor temperature. (Note that the five lines at the top of the screen are customizable, and may be arranged differently 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 Fig. D5-2 - Home display 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”...
  • Page 90 Using the Current User Interface - continued cont. Quick Start This menu gives you an easy way to check or change the most common set- tings on the unit: • CH setpoint • DHW setpoint • Outdoor reset (Note - On some units you cannot disable this function) • Low water temperature • Maximum outdoor temperature • Minimum outdoor temperature • Adjustable high limit • Adjustable low limit Login If you want to change a setup value or function, and the system requires a password, you can enter it here. Test These parameters let you set the burner operation for combustion testing, and control pump operation. Advanced Setup The sub-menus listed here allow you to set up most of the functions on the controller. (For many of these functions, the system will require a password before it will allow you to make changes.) Diagnostics Use the Diagnostics to check the status of the sensors and the digital inputs and outputs. The system also records a history of 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...
  • Page 91 Using the Current User Interface - continued cont. You will notice that the system did not ask you for a password, so this is one of the values that can be changed by anyone. Entering a Time The controller uses several different timing functions, and you can change some of these. (In the example shown in Fig. D5-5, we will use the screen for the Anti Short-Cycle Time. • The current setting appears in the upper right-hand corner of the screen. In this example, this is 1 min- ute. Fig. D5-5 - Changing a timing function • 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. •...
  • Page 92 “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-password state.
  • Page 93 Using the Current User Interface - continued cont. Turning a Function On and Off Some of the values can be enabled or disabled. Figure D5-8 shows one example. • Use the Up- and Down-Arrows to highlight the line you want, then press the round OK button. Changing a Value Using a “Slider” There is another type of control screen you may see. This type of screen uses a “slider” to set the value. This Fig. D5-8 - Enable/ disable screen system is used on the LCD Contrast screen (available under Display Setup.) See Fig. D5-9. • Use the Left- and Right-Arrow buttons to move the bar and adjust the contrast. • When the setting is correct, press the round OK button.

  • Page 94: Reacting To Lockouts On The Current User Interface

    Reacting to Lockouts on the Current User Interface The system responds to three kinds of trouble indica- tions: • A”lockout” is caused by a serious problem that might involve a safety issue. Once the controller enters a lockout, the burner will shut down, and will not be allowed to run again until the cause of the problem is corrected, and you reset the control system. • The system may enter a “hold” for a period of time before locking out. This allows the controller to see if the error becomes resolved prior to the hard lock- out. • An “alert” indicates that some feature of the control system’s operation was not correct, 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 Fig. D6-1 – Resetting the SOLA controller Lockout. A brief explanation of the cause of the Lockout will appear in a line across the bottom of the screen. Correct this by pressing the OK button. You can also press the Reset button on the SOLA controller. See Fig.

  • Page 95: Removing And Replacing The Current User Interface

    Removing and Replacing the Current User Interface Tools and equipment required: Soft cloth (clean towel, etc.) • Small Phillips-head screwdriver (size #1) Procedure 1. Turn off power to the system. Use the main discon- nect switch mounted above the front panel. 2. Place the soft cloth on top of the NT unit. 3. Pull the upper front panel outward. Grip the two handles, and pull straight out. Once the panel is free, handle it carefully, because the wires will still Fig. D7-1 - Current user interface be connected. Swing the panel up and place it, face down, on the cloth. Ribbon cable connectors X01 - 12-pin X07 - 8-pin Fig. D7-2 - Removing the connectors 4. Disconnect the two wiring connectors: •...

  • Page 96: When To Replace A Sola Controller

    9. Plug in connectors X01 and X07. 10. Replace the front panel assembly. 11. Turn on power to the unit. When to Replace a SOLA Controller When a technician is troubleshooting a problem with a NeoTherm 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 programmed dif- ferently for the different NeoTherm models. The replace- ment must be programmed at the factory for the specific model of the NeoTherm unit in which it will be used. Service Manual - NeoTherm 500...

  • Page 97: Removing And Replacing The Sola Controller

    Removing and Replacing the SOLA Controller All of the NT units use the SOLA controller. This procedure explains how to remove and replace this controller. Notice that, as installed in the NT unit, the SOLA controller is mounted “upside down.” This does not affect the way the controller operates. If you order a replacement, the SOLA controller will arrive with the EEPROM (programming software) already installed. The programming is different from one model of NT unit to the next. This means that the SOLA controllers are not interchangeable. When you order the replace- ment, you must specify the exact model of NT unit you have. Tools and equipment required • 1/4” socket Fig. D9-1 - Honeywell SOLA Procedure controller 1. Before you begin, record 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 and cables leading to the unit: At the top of the controller: •...

  • Page 98: D9 Removing And Replacing The Sola Controller

    Removing and Replacing the SOLA Controller (continued) cont. On the right side of the controller (reading top to bottom): • Disconnect connector CP6 from J6 • Disconnect connector CP5 from J5 • Disconnect connector CP4A from J4 (upper part) • Disconnect connector CP4B from J4 (lower part) At the lower center of the controller: • Disconnect the large orange spark cable 5. Now you can remove the controller itself. The controller is attached to the support plate by four clips. To remove the control, push the lower ends of the left side clips, and swing the left side of the control toward you. 6. Mount the new controller using the four clips. 7. Replace the wires and cables listed above. The cables and Green connector mounted in far right position connectors are all labeled. 8. Replace the front cover and turn on the power to the unit. 9. You may need to reset the con- trol on initial startup. Press the “OK” button to reset the control.

  • Page 99: Appendix Sect. Title Page App1 Error Codes

    App1 Appendix 1 - Error Codes This table includes a listing of the faults that might be generated by the controllers, and displayed on the Operator Interface. Some of these can be corrected by an installer changing a parameter, while other conditions are more complicated, and will require a service technician.
  • Page 100 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure Internal fault: Internal fault Invalid burner control state flag 1. Reset module 2. If fault repeats, replace module. Internal fault: Internal fault Safety relay drive cap short 1.
  • Page 101 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure Internal fault: Internal fault Static flame ripple 1. Reset module 2. If fault repeats, replace module. Internal fault: Check flame rod - See Section B37. Flame rod short to ground detected Internal fault in SOLA controller: 1.
  • Page 102 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure AC input phases reversed 1. Check the module and display connections. 2. Check the module power supply and make sure that both frequency and voltage meet the specifications. 3.
  • Page 103 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure Outlet high limit H or L 1. Check wiring and correct any possible errors. See Section B7. 2. Replace the outlet high limit. 3. If previous steps are correct and fault persists, re- place the module.
  • Page 104 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure Internal fault: A2D mismatch. Internal Fault. 1. Reset module. 2. If fault repeats, replace module. Internal fault: Exceeded VSNSR voltage Internal Fault. tolerance 1. Reset module. 2.
  • Page 105 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure Flame lost in run 1. Check main valve wiring and operation - correct any errors. 2. Check the fuel supply. 3. Check fuel pressure and repeat turndown tests. 4.
  • Page 106 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure Fan speed failed during preignition H or L 1. Check wiring and correct any potential wiring errors. See Section B22. 2. Check the VFD’s (Variable-speed Fan Drive) ability to change speeds.
  • Page 107 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure Combustion pressure off H or L 1. Check wiring and correct any errors. 2. Inspect the combustion pressure switch to make sure it is working correctly. 3.
  • Page 108 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure Main valve off 1. Check the main valve terminal wiring and correct any errors. Be sure the On/Off switch on the bottom of the valve is On. See Fig. B11-7. 2.
  • Page 109 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure Safety relay on at safe start check Internal fault. 1. Reset module. 2. If fault repeats, replace module. Invalid blower/ HSI output setting 1. Return to configuration mode and recheck selected parameters, reverify and reset module.
  • Page 110 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure Invalid ignition source setting 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. Invalid interlock open response setting 1.
  • Page 111 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure Invalid postpurge time setting 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. Invalid power up with lockout setting 1.
  • Page 112 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure Unconfigured DHW (Domestic Hot Water) 1. Return to configuration mode and recheck selected high limit setpoint setting parameters, reverify and reset module. 2. If fault repeats, verify electrical grounding. 3.
  • Page 113 App1 Appendix 1 - Error Codes (continued) cont. Code Description L or H Procedure Invalid pressure sensor type setting 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. Invalid outlet high limit enable setting 1.

  • Page 114: App2 Ignition And Firing Sequence

    App2 Appendix 2 - Ignition and Firing Sequence This is the basic operating sequence of the appliance whether there is a DHW, or hydronic call for heat. 1. The unit receives a call for heat. 2. The controller does a check of the safety chain. 3.

  • Page 115: App3 Wiring Diagram

    App3 Appendix 3 - Wiring Diagram Service Manual - NeoTherm 500...
  • Page 116 Service Manual - NeoTherm 500...
  • Page 118 Customer Service and Product Support: Industrial Way, Rochester, NH 03867 • 603.335.6300 • Fax 603.335.3355 Headquarters: 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...

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