Laars MINI-THERM JX Series User manual

FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician,
qualied in hot water boiler and heater installation and maintenance. Improper installation and/or operation
could create carbon monoxide gas in ue gases which could cause serious injury, property damage, or
death. Improper installation and/or operation will void the warranty.
WARNING
If the information in this manual is not followed
exactly, a re or explosion may result causing
property damage, personal injury or loss of life.
Do not store or use gasoline or other ammable
vapors and liquids in the vicinity of this or any
other appliance.
WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use
any phone in your building.
• Immediately call your gas supplier from a
nearby phone. Follow the gas supplier's
instructions.
• If you cannot reach your gas supplier, call the
re department.
Installation and service must be performed by
a qualied installer, service agency, or gas supplier.
AVERTISSEMENT
Assurez-vous de bien suivres les instructions
données dans cette notice pour réduire au
minimum le risque d’incendie ou d’explosion ou
pour éviter tout dommage matériel, toute blessure
ou la mort.
Ne pas entreposer ni utiliser d’essence ni d’autres
vapeurs ou liquides inammables dans le voisinage
de cet appareil ou de tout autre appareil.
QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE GAZ:
• Ne pas tenter d’allumer d’appareils.
• Ne touchez à aucun interrupteur. Ne pas vous servir des
téléphones dansle bâtiment où vous êtes.
• Appelez immédiatement votre fournisseur de
gaz depuis un voisin. Suivez les instructions du
fournisseur.
• Si vous ne pouvez rejoindre le fournisseur de gaz,
appelez le sservice des incendies.
L’installation et l’entretien doivent être assurés par un
installateur ou un service d’entretien qualié ou par le
fournisseur de gaz.
Residential
Gas-Fired
Hydronic Boilers
Sizes 50-200 MBTU/h
Installation and Operation Instructions for
®
MINI-THERM
JX
H2411200A
Installation and Operation Instructions Document 1478A

TABLE OF CONTENTS
SECTION 1 GENERAL INFORMATION
1.A Safety Warnings ..................................... 4
1.B Introduction ............................................. 6
1.C Warranty ................................................. 6
1.D Model Number and Nomenclature .........6
1.E Model Overview ...................................... 7
1.F Temperature and Pressure Gauge ......... 7
1.G Dimensions ............................................. 9
1.H The Installation Kit ................................ 10
1. I Accessory Kits Available.......................10
SECTION 2 LOCATING THE BOILER
2.A Field Assembly ..................................... 10
2.B Boiler Placement .................................. 10
2.C Clearances ........................................... 10
SECTION 3 AIR AND VENTING
3.A Safety Warnings ................................... 11
3.B Combustion Air Supply ......................... 12
3.C Venting .................................................13
3.D Vertical Venting - Category I ................ 14
3.E Locations for Vent Pipe Terminator....... 15
3.F Venting with a Power Venter ...............16
3.G Common Vent Test ............................... 16
SECTION 4 GAS CONNECTIONS
4.A Gas Supply and Piping ......................... 17
4.B LP Gas Conversion .............................. 18
4.C Special Precautions for LP Gas............ 18
SECTION 5 PUMP REQUIREMENTS
5.A Pump Sizing ......................................... 19
SECTION 6 WATER CONNECTIONS
6.A Water Piping ......................................... 20
6.B Low Loss Header .................................20
6.C Oxygen Permeable Systems ................ 20
6.D Anti-freeze ............................................ 20
6.E Typical Plumbing Diagrams .................. 21
SECTION 7 ELECTRICAL AND
WIRING DIAGRAMS
7.A Safety Warnings ................................... 23
7.B Main Power, 120V ................................ 23
7.C Outdoor Sensor .................................... 23
7.D Field Connections .............................. 24
7.D.1 TB1 (Term Block 1 -TT, DHW, OAS) . 24
7.D.1.a TT (Central Heat)..................................24
7.D.1.b DHW. ................................................... 24
7.D.1.c Field Interlocks ..................................... 24
7.D.1.d PV Terminals ....................................... 24
7.D.1.e WWSD + COM .................................... 24
7.D.1.f OAS + COM ......................................... 24
7.D.2 TB2 (for pumps and aux power) .......25
7.D.2.a Boiler Pump .......................................... 25
7.D.2.b SYS Pump ............................................ 25
7.D.2.c Aux Power ............................................ 25
7.D.3 TB3 (for optional equipment) ............ 25
7.D.3.a DHW Pump ..........................................25
7.D.3.b DHW Aquastat ...................................... 25
7.E Wiring Connects, Power Vent and Air .. 26
7.F Wiring Diagram ..................................... 28
7.G Logic Diagram ...................................... 29
SECTION 8 THE DIGITAL DASHBOARD
8.A Getting to know the Digital Dashboard. 3 0
8.A.1 The Lo Limit Dial
(Advanced Programing) .......................31
8.A.2 The Hi Limit Dial
(Program Select) .................................. 31
8.A.3 Economy
(WWSD Curve Adjust and more) .......... 31
8.A.4 Mode ................................................31
8.A.5 Control LEDs ..................................... 31
8.A.5.a TS ACTIVE (TEMP) ............................ 31
8.A.5.b HIGH TEMP ......................................... 31
8.A.5.c LWS ACTIVE (LWCO) .........................31
8.A.5.d LOW WATER ....................................... 31
8.A.5.e TEMP ACTIVE (ECONOMY) ...............31
8.A.5.f TEMP TARGET .................................. 31
8.A.6 Digital LEDs . .................................... 32
8.A.7 Ignition LEDs ..................................... 32
8.A.7.a LIMITS ................................................. 32
8.A.7.b V-PWR .................................................. 32
8.A.7.c V-SW ................................................... 32
8.A.7.d FLAME .................................................32
LAARS Heating Systems

8.B Advanced Programing .......................32
8.B.1 Fahrenheit or Celsius ........................... 32
8.B.2 Low Water Cut-O󰀨 ................................ 32
8.B.2.a RESET, Manual or Automatic ............... 32
8.B.2.b Testing Low Water Cut OFF ................. 33
8.B.3 High Limit Di󰀨erential ........................... 33
8.C Sensor Programming .........................33
8.C.1 Outdoor Sensors .................................. 33
8.C.2 Setting Warm Weather Shutdown ........ 33
8.C.3 Adjusting Reset Ratio) .......................... 34
8.C.3.a Outdoor Reset Thermal Boost Function 3 4
8.C.4 Restore Factory Default Settings .........35
8.D View Current Settings ......................... 35
8.E DHW Functionality ................................ 35
SECTION 9 INITIAL STARTUP
9.A Filling the 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.A.1 Access Cover Removal ...................... 40
10.A.2 Flue Collector Access .......................... 40
10.A.3 Side Panel Removal ............................ 41
10.A.4 Draft Hood Removal ........................... 41
10.B Maintenance ......................................... 42
SECTION 11 OPERATING DETAILS AND
TROUBLESHOOTING
11.A Operating Details .................................. 43
11.B Electrical Troubleshooting .................... 43
11.C Troubleshooting Table .......................... 44
11.D Troubleshooting Flow Charts ................ 45
11.D.1 Troubleshtng Flow Chart 1 (burners o󰀨) . . 45
11.D.2 Troubleshtng Flow Chart 2 (burners on) . 46
SECTION 12 REPLACEMENT PARTS
12.A Parts Illustrations .................................. 47
12.B Parts List ..............................................49
12.C Accessories List ...................................50
12.D Glossary of Terms................................. 51
MINI-THERM JX Residential Boilers
®

Page 4
1.A Safety Warnings
WARNING
Carbon Monoxide Hazard
Improper adjustment of the burners may lead to poor
combustion quality, increasing the amount of carbon
monoxide produced. Excessive carbon monoxide
levels may lead to personal injury or death.
WARNING
This unit must be installed in accordance with the
procedures detailed in this manual, or the manufacturers
warranty will be voided. The installation must conform
to the requirements of the local jurisdiction having
authority, and, in the United States, to the latest edition
of the National Fuel Gas Code,ANSI Z223.1/NFPA54.
In Canada, the installation must conform to the latest
edition of CSAB149.1 Natural Gas and Propane Gas
Installation Code, and/or local codes. Where required
by the authority having jurisdiction, the installation of
these units must conform to the Standard for Controls
and Safety Devices forAutomatically Fired Boilers,
ANSI/ASME CSD-1. Any modifi cations to the boiler, its
gas controls, or wiring may void the warranty. If fi eld
conditions require modifi cations, consult the factory
representative before initiating such modifi cations.
WARNING
• Water temperature over 125°F (52°C) can cause
severe burns instantly or death from scalds.
• Children, disabled and
elderly are at highest
risk of being scalded.
• See instruction manual
before setting temperature
at the unit.
• Feel water before bathing
or showering.
• If this unit is used
to produce water that could scald if too hot, such
as domestic hot water 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).
WARNING
Fire or Explosion Hazard
Improper confi guration can cause fuel buildup and
explosion. Improper user operation may result in
property loss, severe physical injury, or death.
Any changes to safety-related confi guration
parameters must only be done by experienced and/or
licensed burner/boiler operators and mechanics.
If any odor of gas is detected, or if the gas burner does
not appear to be functioning in a normal manner, close
the main gas shutoff valve. Do not shut off the power
switch. Contact your heating contractor, gas company,
or factory representative.
NOTE: This unit is protected against hydronic
over-pressurization. A pressure relief valve is included
with each unit.
WARNING Indicates an imminently hazardous situation which, if not
avoided, can or will result in death or serious injury and can
or will result in catastrophic property damage.
CAUTION Indicates a potentially hazardous situation which, if not avoided,
may result in moderate injury and/or property damage.
NOTE: Indicates instructions that are important to that topic but not
related to personal injury or property damage.
Safety Warnings are used throughout this manual to bring attention to the presence of hazards with various
risk levels and to off er important information concerning the life of this product. There are 3 basic types.
WARNING
CANCER AND REPRODUCTIVE HARM.
WWW.P65WARNINGS.CA.GOV.
AS REQUIRED BY THE STATE OF
CALIFORNIA PROPOSITION 65.
1
2
3
SECTION 1 GENERAL INFORMATION
LAARS Heating Systems

Page 5
WARNING
Electrical Shock Hazard
Electrical shock can cause severe injury, 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 off more than one power supply
to disconnect.
All electrical wiring is to be done in accordance with
local codes, or in the absence of local codes, with: 1)
The National Electrical CodeANSI/NFPA No. 70 - latest
Edition, or 2) CSASTD. C22.1 “Canadian Electrical Code
- Part 1.” This appliance must be electrically grounded in
accordance with these codes.
WARNING
The Repair Parts list designates parts that contain
refractory ceramic fi bers (RCF). RCF has been classifi ed
as a possible human carcinogen. When exposed to
temperatures above 180ºF, such as during direct fl ame
contact, RCF changes into crystalline silica, a known
carcinogen. When disturbed as a result of servicing or
repair, these substances become airborne and, if inhaled,
may be hazardous to your health.
Do not remove or replace RCF parts or attempt any
service or repair work involving RCF without wearing
the following protective gear:
1. ANational Institute for Occupational Safety and
Health (NIOSH) approved respirator.
2. Long sleeved, loose fi tting clothing.
3. Gloves.
4. Eye Protection.
WARNING
Should overheating occur or the gas supply fail to
shut off , do not turn off or disconnect the electrical
supply to the pump. Instead, shut off the gas supply
at a location external to the appliance.
AVERTISSEMENT
En cas de surchauff e au si !’admission de gaz ne
peut etre coupee, ne pas couper ni debrancher
l’alimentatio electrique de la pompe. Fermer plutot
le robinet d’admission de gaz a l’exterieur de
l’appareil.
MINI-THERM JX Residential Boilers
®

Page 6
Consult the rating plate on the unit. The following
information describes the model number structure.
1.B Introduction
1.C Warranty
Model Nomenclature
1.D Model Number and Nomenclature
1C. Model Number and Nomenclature
The rating plate on the side of your Mini-Therm shows your Model Number. The original characteristics of
your unit can be identified using this nomenclature from your Model Number.
0 1 2 3 4 5 6 7 8 9 10
SIZE
0
5
0
0
7
5
1
0
0
1
2
5
1
5
0
2
0
0
Table 1. Nomenclature.
BJX = Mini-Therm Series
3 RD thru5thCharacters(Size)InputMBTU/HR
6th Character (fuel)
N = Natural Gas
7th Configuration
X
N
X
L
P
U
1
LAARS Heating Systems
The Laars Mini-Therm JX boilers are covered by a
limited warranty. The owner should complete the
warranty registration online by going to www.Laars.
com. and selecting the ‘Support’ pull-down to nd the
new product warranty registration form.
All warranty claims must be made to an authorized
Laars representative or directly to the factory. Claims
must include the boiler serial number and model
(this information can be found on the rating plate),
installation date, and name of the installer. Shipping
costs are not included in the warranty coverage.
Some accessory items are shipped in separate
packages. Verify receipt of all packages listed on
the packing slip. Inspect everything for damage
immediately upon delivery, and advise the carrier of
any shortages or damage. Any such claims should
be led with the carrier. The carrier, not the shipper,
is responsible for shortages and damage to the
shipment whether visible or concealed.
The warranty does not cover damage caused by
improper assembly installation, operation or eld
modication.
This manual provides information necessary for the
installation, operation, and maintenance of the LAARS
Heating Systems Mini-Therm JX. Read it carefully
before starting the installation.
All application and installation procedures should
be reviewed completely before proceeding with the
installation. Consult the LAARS Heating Systems
factory, or local factory representative, with any
problems or questions regarding this equipment.
Experience has shown that most operating problems
are caused by improper installation.
1st, 2nd Characters (Series Name)
JX = Mini-Therm JX
3rd thru 5th Characters (Size)
Input MBTU / H
6th Character (fuel)
N = Natural Gas
7th Character (Cong)
X = Standard 50-100
L = Standard 125-200
(Low Loss Header & Pump Installed)
P = 50-100 with Pump Kit
8th Character (Altitude in Feet)
X = (0 - 2,000)
H = (2,001 - 5,000)
I = (5,001 - 8,000)
9th Character (Country)
U = USA & Canada
10th Character (Revision)
1 = 1st Revision
J MODEL
MINITHERM JX

Page 7
Figure 1. Largest and Smallest
200 MBH
Rating Plate
with Model Number
and Nomenclature
Low Loss Header.
Models 125 - 200 only
50 MBH
1.E Model Overview
The Temperature and Pressure gauge is viewable just above
the Digital Dashboard. The pressure is sensed at the top front
section of the inlet/outlet header. The temperature is sensed at
the outlet pipe.
Figure 2. Gauges
1.F Temperature and Pressure Gauge
MINI-THERM JX Residential Boilers
®

Page 8
The Digital
Dashboard
Panel
Lock
Temp and Pressure
Gauges
Drain
Rating Plate
Pressure
Relief Valve
Pressure
Relief Valve
‘Knock-outs’
Gas Supply
Gas Supply
Main Power 120V
Connections
See 7.B on page 23
See 7.D on page 24
Gas Valve
Pilot Ignitor
Sensor Shown with front cover o󰀨
Field Connections
TB1
DHW Relay
Connections
TB3
Field Connections
TB2
Low Loss Header
Vent Damper (sizes 125 - 200)
Hydronic Supply
Hydronic Return
Figure 3. Location of Components
1.E Model Overview (continued)
See 8.A on
page 30
LAARS Heating Systems

Page 9
Table 1. Dimensions
1.G Dimensions
Dimensional
Data
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 (125, 150, 200)
OUT (Supply)
IN (Return)
1-1/4” NPT Male
1-1/4” NPT Male
F1
7"
18cm
Right View
(50, 75, 100)
In Return
Top View
Low Loss Header & Damper not shown
T&P Gauge
Control Display
PRV Out Supply
C
WATER
CONN
GAS
CONN
SIZE
A B C D E
F1 F2
in. cm in, cm in. cm in, cm in. cm in. cm in. cm in.
(inches) (inches)
cm 1-1/4
3/4
50 11-3/4 30 31-5/8 80 25-1/8 64 24-3/4 63 27-5/8 70 24-7/8 63
- -
4 10 1-1/4
3/4
75 14-1/2 37 31-5/8 80 25-5/8 65 24-3/4 63 28-5/8 73 24-7/8 63
24-7/8 63
- -
- -
5 13 1-1/4
3/4
100 17-3/8 45 32-1/8 82 25-1/2 65 25-3/8 65 28-5/8 73 5 13 1-1/4
3/4
125 20-1/8 52 32-1/8 82 25 64 25-3/8 65 28-5/8 73 -
-
31 79 6 15 1-1/4
3/4
150 23 59 32-1/8 82 25 64 25-3/8 65 28-5/8 73 -
-
31 79 6 15 1-1/4
3/4
200 28-3/8 73 32-1/4 82 24-5/8 63 26-1/4 67 28-5/8 73 -
-
31 79 7 18 1-1/4
3/4
Front View
Draft Diverter
Damper
6”
3-1/4” 8.3cm
Low Loss
Gas
Supply
Header
A
D B
V
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
(125, 150, 200)
OUT (Supply)
IN (Return)
1-1/4” NPT Male
1-1/4” NPT Male
F1
7"
18cm
Right View
(50, 75, 100)
In Return
Top View
Low Loss Header & Damper not shown
T&P Gauge
Control Display
PRV Out Supply
C
WATER
CONN
GAS
CONN
SIZE
A B C D E
F1 F2
in. cm in, cm in. cm in, cm in. cm in. cm in. cm in.
(inches) (inches)
cm 1-1/4
3/4
50 11-3/4 30 31-5/8 80 25-1/8 64 24-3/4 63 27-5/8 70 24-7/8 63
- -
4 10 1-1/4
3/4
75 14-1/2 37 31-5/8 80 25-5/8 65 24-3/4 63 28-5/8 73 24-7/8 63
24-7/8 63
- -
- -
5 13 1-1/4
3/4
100 17-3/8 45 32-1/8 82 25-1/2 65 25-3/8 65 28-5/8 73 5 13 1-1/4
3/4
125 20-1/8 52 32-1/8 82 25 64 25-3/8 65 28-5/8 73 -
-
31 79 6 15 1-1/4
3/4
150 23 59 32-1/8 82 25 64 25-3/8 65 28-5/8 73 -
-
31 79 6 15 1-1/4
3/4
200 28-3/8 73 32-1/4 82 24-5/8 63 26-1/4 67 28-5/8 73 -
-
31 79 7 18 1-1/4
3/4
Front View
Draft Diverter
Damper
6”3-1/4” 8.3cm
Low Loss
Gas
Supply
Header
A
D B
V
V
MINI-THERM JX Residential Boilers
®

Page 10
Figure 4. Minimum Clearances
SECTION 2 LOCATING THE BOILER
2.A Field Assembly
This boiler is shipped with an automatic vent damper that
must be assembled onto the vent collar on the top of the
boiler, and then plugged into the unit using the dedicated
harness.
2.B Boiler Placement and Clearances
This boiler is design certied by CSA-International for
indoor installation on combustible ooring, in basements,
in closets, utility rooms or alcoves. These units must
never be installed on carpeting.
1. This boiler is designed for indoor installations only
and should be located to provide clearances on all
sides for maintenance and inspection. See Figure
4. It should not be located in an area where leakage
of any connections will result in damage to the
area adjacent to the unit or to lower oors of the
structure. When such a location is not available, it is
recommended that a suitable drain pan, adequately
drained, be installed under the unit.
2. A minimum of 15” (381mm) access must be available
in front of the boiler for burner removal. Consult
local codes for clearances to hot water pipes and
accessories.
3. If the boiler is to be installed in a garage, all burners
and burner ignition devices must have a minimum 18”
(457mm) clearance above the oor.
4. Boilers can be installed in a closet as long as all
minimum clearances are followed, including between
the front of the boiler and the closet door when it is
closed. See Figure 4. Consult the American National
Standard Z21.13 for more information concerning
closet installations. In Canada, refer to the latest
edition of CSA-B149.1.
5. When vented vertically, the unit must be located as
close as practical to the vertical section of the vent.
When a power venter is used with a terminal through
a wall, and there is a potential for snow accumulation,
the terminal must be installed at an appropriate level
above grade or the maximum expected snow line.
NOTE: For installation on combustible ooring.
NOTE: For Closet Installation Clearances, the
minimum clearance between hot water pipes
and combustible construction is 1” (2.5 cm.)
LAARS Heating Systems
4” 10 cm
4” 10 cm
6” 15 cm
20” 51 cm
2” 5 cm
1.H The Installation Kit
This residential unit is shipped in a single crate
with a boxed installation kit that contains these
components.
1. I/O Manual
2. Vent Damper
3. Burner Air Shutter Gauge (Mini Gauge)
Optional:
1. Circulator pump & ange kit (50 - 100)
1.I Accessory Kits Available
See Section 12.C on page 50 for part numbers.
• Low Loss Header with Integral Pump for 50 - 100
(Standard on larger models)
• Conversion kits for LP and altitude are available
from 0 to 10,000’ both fuels.
• Domestic Hot Water Pump Relay Kit
• Power Vent Kits
• Outdoor Air Sensor