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Page 42

these basic items listed be inspected by a qualified 

service technician every year. 

 

a. Water temperature controls.

 

b. Pilot safety system.

 

c.  Automatic gas valves.

 

d.  Low Water Cut Off (ensuring the sensor well is 

cleaned of exterior residue periodically based 

on system conditions)

 

e. Mechanical flue damper operation.

 

f.   Pressure Relief Valve. The pressure relief 

valve lever must be tripped at least once a 

year to ensure that the waterways are clear. 

When manually operating lever, water will 

discharge through drain line and precautions 

must be taken to avoid contact with the hot 

water and to avoid water damage. 

10.   Inspect the heat exchanger for fouling. Fouling 

on the external surfaces of the heat exchanger 
is caused by incomplete combustion, and is a 

sign of venting and/or combustion air problems 

or too cold of a return water temperature. The 

heat exchanger can be inspected by using a 

flashlight and placing a mirror under the burners. 

An alternate method is to remove the top panel 

to inspect the exchanger from above. This boiler 

has easy access through the top cover and the 

flue collector for inspection of the heat exchanger. 

It is critical to ensure that the flue collector sits in 

the proper position so that no flue products will 

escape into the living area of the building. 

  If cleaning is required:
 

a.  Shut off all power to the boiler.

 

b.   Remove the top, flue collector, and heat 

exchanger baffles.

 

c.  Remove the burners.

 

d.   Use a hand-operated spray bottle filled with 

water, and a wire brush to clean soot and 

loose scale from the underside of the heat 

exchanger. DO NOT USE COMPRESSED 

AIR, HIGH PRESSURE WATER, OR A 

GARDEN HOSE.

 

e.   Clean any fallen debris from the bottom of the 

unit.

 

f.   Check to make sure the burner ports and pilot 

assembly are free of debris before returning 

the burners to their original positions.

 

g.   Reassemble the boiler in reverse order, 

making sure to replace the heat exchanger 

baffles and flue collector into the proper 

location. 

10.B 

Maintenance

 

WARNING

The Warranty does not cover damage caused by 

lack of required maintenance, lack of water flow, 

or improper operating practices.

 

 

AVERTISSEMENT

 

La garantie ne couvre pas les dommages causés 

par l'absence d'entretien, absence de débit d'eau, 

ou pratiques de fonctionnement irrégulières

1.   Lubricate any motor bearings that are not sealed 

bearings per the instructions.

2.   If a strainer is employed in a pressure reducing valve 

or the piping, clean it annually or as needed.

3.   At start-up, and periodically thereafter, the burner 

and pilot flames should be observed. If the flame has 

the appearance of “sooting” tips, check for debris 

near the orifices. Clean any debris from orifice area 

and remove burners to ensure they are debris free 

inside and out. If this doesn’t clear the issue the heat 

exchanger likely needs cleaning.

4.   Ensure vent damper motors open and close by 

watching the connecting rod between the stack and 

the motor housing. The boiler should never start if 

the damper is not in the open position.  If it does, it is 

critical to safe operation that this gets repaired.

5.   Inspect the venting system for obstruction, leakage 

or corrosion at least once a year. Any venting system 

issues must be repaired before restarting the boiler. 

6.   Keep the boiler area clear and free from combustible 

materials, gasoline, and other flammable vapors and 

liquids.

7.   Be sure that all combustion air and ventilation 

openings are unobstructed. 

8.   If the boiler is not going to be used for long periods 

of time in locations where freezing occurs, it should 

be completely drained of all water. To accomplish 

this, there is a drain valve on the right side of the 

boiler which can be opened. This will drain the right 

side of the boiler. There are two plugs located on 

the left side of the heater which can be accessed 

by removing the side panel which must be removed 

to drain that side. 

BOTH SIDES MUST BE 

DRAINED. 

 

See Section 9.E on page 40

9 .  The gas and electric controls on the boiler are 

engineered for long life and dependable operation, 
but the safety of the equipment depends on their 

proper functioning. It is 

strongly recommended that 

 

LAARS Heating Systems

Summary of Contents for MINI-THERM JX

Page 1: ...ment Installation and service must be performed by a qualified installer service agency or gas supplier AVERTISSEMENT Assurez vous de bien suivres les instructions donn es dans cette notice pour r dui...

Page 2: ...0 6 D Typical Plumbing Diagrams 21 SECTION 7 ELECTRICAL AND WIRING DIAGRAMS 7 A Safety Warnings 23 7 B Main Power 120V 15 Amp Circuit 23 7 C Outdoor Sensor 23 7 D Field Connections 24 7 D 1 TB1 Term B...

Page 3: ...System 36 9 B System Start Up Seq of Operation 36 9 C Proper Pilot Flame 38 9 D Lighting Instructions Decal 39 9 E System Shutdown 40 SECTION 10 MAINTENANCE 10 A Removing the Covers and Panels 40 10...

Page 4: ...justing high limit to anything other than 190 F 88 C Installing an outdoor sensor for the purpose of setting the Reset Curve Changing the temp readout from Fahrenheit to Celsius or back to Fahrenheit...

Page 5: ...ater use adjust the outlet control limit or use temperature limiting valves to obtain a maximum water temperature of 125 F 52 C WARNING The inlet gas pressure to the unit must not exceed 13 W C 3 2kPa...

Page 6: ...njury death or property damage Disconnect the power supply before beginning installation or changing the wiring to prevent electrical shock or damage to the equipment It may be necessary to turn o mor...

Page 7: ...Connections See 7 B on page 23 See 7 D on page 24 Gas Valve Pilot Ignitor Sensor Shown with front cover off Field Connections TB1 DHW Relay Connections TB3 Field Connections TB2 Low Loss Header Vent...

Page 8: ...nt cover and allow for advanced settings and installations that have outdoor reset and Low Water Cut Off LWCO with manual reset and several other advanced settings See SECTION 8 on page 30 Figure 4 Sy...

Page 9: ...4 Front View Draft Diverter Damper 6 15 3cm 3 1 4 8 3cm Low Loss Gas Supply Header A D B V 1 1 4 NPT Female OUT Supply IN Return 1 1 4 NPT Female 53cm 23cm F2 11 8cm 4 5 8 21 9 1 8 Max E Right View 1...

Page 10: ...Installation Clearances the minimum clearance between hot water pipes and combustible construction is 1 2 5 cm 2 A minimum of 15 381mm access must be available in front of the boiler for burner remov...

Page 11: ...es Improper venting of this appliance can result in excessive levels of carbon monoxide which can result in severe personal injury or death AVERTISSEMENT Cette chaudi re doit tre ventil conform ment a...

Page 12: ...openings one within 12 inches 305mm of the ceiling the other within 12 inches 305mm of the floor NOTE In Canada follow Canadian Standard CAN CSA B149 1 or local codes Outside Air Supply When combusti...

Page 13: ...p is designed so that it can be easily removed for normal boiler service and inspection without removal of the venting Avoid terminating boiler vents near air conditioning or air supply fans The fans...

Page 14: ...d expected system water temperatures Also ensure the boiler s anti condensing features are utilized by properly wiring the system pumps See Figure 28 on page 27 WARNING Do not store any chemical clean...

Page 15: ...c e d i s n i o t e c n a r a e l C G H Clearance to each side of centerline extended above meter regulator assy 3 ft 91 cm within a height of 15 ft 4 6 m m c 1 9 t f 3 t e l t u o t n e v r o t a l u...

Page 16: ...ANSI Z223 1 NFPA 54 AVERTISSEMENT Lorsqu une chaudi re existante est retir e d un syst me de ventilation commun le syst me de ventilation commun est susceptible d tre trop grand pour une ventilation a...

Page 17: ...ed gas meter Gas supply pressures to the heater are listed in Table 3 SECTION 4 Gas Connections 4 A Gas Supply and Piping Follow this guideline checklist for the gas supply installation 1 Gas piping i...

Page 18: ...e DO NOT ATTEMPT TO CONVERT THIS HEATER FOR USE WITH ANY OTHER TYPE OF FUEL AVERTISSEMENT Le unit est con u pour tre utilis avec du gaz naturel ou du gaz LP mais seulement des navires de l usine comme...

Page 19: ...eadloss See Table 5 Primary Secondary systems and boilers with LLH systems can be used to avoid needing larger system pumps Water Flow Requirements Electrical Data All Sizes with Low Loss Header witho...

Page 20: ...system utilizing oxygen permeable tubing Provide a water to water heat exchanger between systems to prevent corrosion of ferrous metals such as the boiler s piping wet walls etc Air elimination devic...

Page 21: ...es Indirect Tank Air Scoop Zone Pumps mustbesized properly Valves Check Valves DHW Pump Drains Drains Drains Drains Check Valve Valves Indirect Tank Check Valve Valves Indirect Tank DHW Pump DHW Pump...

Page 22: ...and 100 Low Loss Header is standard on models 125 150 and 200 and Optional for models 50 75 and 100 Figure 16 Low Loss Header with Zone Pumps and DHW Typical Plumbing Diagrams continued KEY PUMP CHECK...

Page 23: ...nly 7 A Safety Warnings NOTE All internal electrical components have been pre wired No attempt should be made to connect electrical wires to any other location except the terminal blocks and line volt...

Page 24: ...the optional DHW Relay Kit will control the boiler to the high limit setpoint See SECTION 8 for functionality 7 D 1 c Field Interlocks Field Interlocks allow for auxiliary limits or LWCO Breaking the...

Page 25: ...sation due to low inlet water temperature 7 D 2 c Aux Power This terminal and the 120V N terminal provide constant high voltage to accessories such as power vent combustion air and or zone relay syste...

Page 26: ...Air System Laars Power Vent Kit L1 N T1 T2 T3 L1 N T1 T2 T3 L N 1 2 4 Example Fields Controls CAS 4 Wiring to JX Combus on Air System Example Laars Power Vent Kit and Fields Controls CAS 4 Wiring to...

Page 27: ...d the total capacity of the transformers See Zone Valve manufacturer s installation instructions for valve electrical requirements Three Wire Zone Valves need an Isolation Relay if not using a zone co...

Page 28: ...4V L PILOT VALVE 24V L MAIN VALVE 24V N Y GAS VALVE S BLOCKED VENT SWITCH SWITCH ROLL OUT 24VAC 120VAC R O A A OAS COM W W SD X1 X2 X4 Y Y R R CONNECTOR DAMPER O Y Y R R R R TRANSFORMER BOILER PUMP CO...

Page 29: ...X1 2 X1 8 X1 5 MAIN VALVE 24V N 24V L 24V L SPARK IGNITOR GENERATOR SPARK J1 WATER TEMP SENSOR FACTORY INSTALLED X3 5 POWER VENTER PROOF OF FAN not supplied FACTORY JUMPERED VENT DAMPER PROOF OF OPEN...

Page 30: ...it to Celsius or back to Fahrenheit To change the economy settings 8 A 2 The HI LIMIT Dial Program Select The high limit is factory set at 190 F To adjust turn the HI TEMP dial until the desired setti...

Page 31: ...ctive IMPORTANT NOTE If the sensor installation has been modified to a single function sensor well this LED will not illuminate indicating that the control is not providing low water cut off functiona...

Page 32: ...proceed to Step 3 If you are using outdoor sensor and you ve programed your Reset Ratio then skip the Economy dial and proceed to Step 4 Always finish with Step 4 to ensure the high limit is properly...

Page 33: ...eset press and hold the Mode button The LED will illuminate solid red after 10 to 30 seconds but continue to hold the Mode button for 60 seconds and the LWCO will shut down the boiler and the LOW WATE...

Page 34: ...l regulate the boiler s temperature based on the temperature outside On cold days the boiler will run at higher temperatures to meet the heating load in the house On warmer days the boiler will run at...

Page 35: ...f the LOW WATER light is ng the control has been programmed to provide lock rotection in the event a low water condition is detected Manual Reset Low Water Cut Off ORTANT The system must be checked by...

Page 36: ...prevent air locked zones and boiler damage M START UP Carbon monoxide hazard The vent damper must be fully open and the flue must be clear before the main burner fires If the burner fires when the ve...

Page 37: ...he manual gas valve and verify that the burner flame is extinguished and the boiler continues to try to restart continuous retry of pilot You can then allow the boiler to restart by opening the manual...

Page 38: ...and the pilot should be adjusted down using the valve s pilot adjustment screw shown in Figure 42 If the flame is small and the inner cone does not engulf the pilot ignitor sensor then the pilot is u...

Page 39: ...ndie ou une explosion entra nant des dommages des blessures ou la mort A Cet appareil est muni d un dispositif d allumage qui allume automatiquement la veilleuse Ne tentez pas d allumer la veilleus ma...

Page 40: ...his panel off in normal operation High voltage and temperatures could cause a hazardous condition 10 A 1 Access Cover Removal To remove the front access cover simply turn the lock at the top center of...

Page 41: ...l 10 A 3 Side Panel Removal Remove the front access and the top as described previously Drain the boiler and remove the drain valve and or the PRV and associated fittings depending on the panel being...

Page 42: ...n 10 B Maintenance WARNING The Warranty does not cover damage caused by lack of required maintenance lack of water flow or improper operating practices AVERTISSEMENT La garantie ne couvre pas les domm...

Page 43: ...or power on any switch on the boiler 5 To perform voltage checks on 120VAC attach one meter lead to either terminal 2 or 3 of TB1 Use the other lead to check for power at any high voltage terminal or...

Page 44: ...efficiency Replace heat exchanger 6 Pump noisy Air in volute Bleed air from volute Check pump alignment Worn bearings Replace worn parts 7 Boiler pounding or knocking Water flow too low through boiler...

Page 45: ...ature drops to the automatically calculated Target Temp Differential Is the Green LED TEMP ACTIVE On The Control is Not Powered The Temp Active LED will be on at all times when the control is powered...

Page 46: ...VAC on the Gas Valve WARNING 11 D 2 Troubleshooting Flow Chart 2 burners on from previous page Is There 24 VAC on the PV terminal of the Valve If Flame Light is solid spark should be off and 24VAC sho...

Page 47: ...and system piping is simplified Primary Secondary Piping Two or more interconnecting circulating loops each with its own pump Primary Boiler Circuit Secondary System Circuit Reverse Return Piping Bal...

Page 48: ...X 5 R 3 4 0 3 X 5 R e d i S A3 Panel 8 3 0 3 X 0 2 8 3 0 3 X 5 1 8 3 0 3 X 2 1 8 3 0 3 X 0 1 8 3 0 3 X 7 8 3 0 3 X 5 t n o r F A4 Front 5 4 0 3 X 0 2 R 5 4 0 3 X 5 1 R 5 4 0 3 X 2 1 R 5 4 0 3 X 0 1 R...

Page 49: ...Page 49 C2 A7 A2 A9 A1 A8 A10 A3 A4 A12 A13 A14 D3 B2 B4 B5 C6 C3 B6 D13 D2 B8 B9 A15 D1 A6 A5 A16 A17 B1 B7 C1 D4 C5 C4 B4 B3 MINI THERM JX Residential Boilers...

Page 50: ...L0039000 L0039000 L0039000 L0039000 2001 5000 L0032900 L0032900 L0032900 L0032900 L0032900 L0032900 5001 8000 L0032800 L0032800 L0032800 L0032800 L0032800 L0032800 8001 10000 L0032700 L0032700 L00327...

Page 51: ...2 not shown 1 H2413100 INSTRUCTIONS INSTALLATION DHW RELAY KIT JX n 1 5X7002 DHW PANEL ASSY JX ECN DECIMALS XX DRAFT CHECK RELEASE REVISIONS K REV CF 6JUL20 DWG CHANGE IN WRITING BY LAARS HEATING SYST...

Page 52: ...6 Fax 800 559 1583 Headquarters 20 Industrial Way Rochester NH USA 03867 603 335 6300 Fax 603 335 3355 9 Brigden Gate Halton Hills Ontario Canada L7G 0A3 905 203 0600 Fax 905 636 0666 www Laars com Li...

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