LAARS MS-080 User Manual

Installation and Operation Instructions Document 2155

Installation and Operation
Instructions for

™

Mighty Stack

Water Heater
Model MS-080
Sizes 199, 300, 399

FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician,

qualified in hot water water heater installation and maintenance. Improper installation and/or operation
could create carbon monoxide gas in flue gases which could cause serious injury, property damage,
or death. Improper installation and/or operation will void the warranty. For indoor installations, as an
additional measure of safety, Laars strongly recommends installation of suitable Carbon Monoxide
detectors in the vicinity of this appliance and in any adjacent occupied spaces.

WARNING

If the information in this manual is not
followed exactly, a fire or explosion may
result causing property damage, personal
injury or loss of life.

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

• 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 fire department.
Installation and service must be performed
by a qualified installer, service agency, or gas
supplier.

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 inflammables 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
trouvez.

• 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 qualifié ou
par le fournisseur de gaz.

AVERTISSEMENT

H2350400-

Page 2

Laars Heating Systems

TABLE OF CONTENTS

SECTION 1.
General Information

1.1 Introduction ...................................................... 3

1.2 Model Identication .......................................... 4

1.3 Warranty .......................................................... 4

1.4 Dimensions ...................................................... 4

1.5 Locating the Appliance..................................... 4

1.6 Locating Appliance for Correct Horizontal Vent/

Ducted Air Distance From Outside Wall .......... 6

SECTION 2.
Venting and Combustion Air

2.1 Combustion Air ................................................ 7

2.1.1 Combustion Air From Room ............................ 7

2.1.2 Intake Combustion Air...................................... 8

2.2 Venting ............................................................. 8

2.2.1 Vent Categories ............................................... 8

2.2.2 Category I Vent ................................................ 8

2.2.3 Common Venting Systems .............................. 8

2.2.4 Category III Vent .............................................. 9

2.3 Locating Vent & Combustion Air Terminals ...... 9

2.3.1 Side Wall Vent Terminal ................................... 9

2.3.2 Side Wall Combustion Air Terminal ................ 12

2.3.3 Vertical Vent Terminal .................................... 12

2.3.4 Vertical Combustion Air Terminal ................... 12

2.4 Common Vent Test ........................................12

2.5 Vent Terminals for Outdoor Units ................... 13

SECTION 3.
Gas Supply and Piping

3.1 Gas Supply and Piping .................................. 15

SECTION 4.
Water Connections

4.1 Water System Piping ..................................... 16

4.2 Hot Water Supply Piping ................................ 16

4.3 Water Flow Requirements ............................. 16

4.4 Combined Water Heating (potable)

and Space Heating ........................................ 16

4.5 Freeze Protection .......................................... 16

SECTION 6.
Operating Instructions

6.1 Filling the Water Heater System .................... 20

6.2 Operating Temperature Control ..................... 20

6.3 External Water Heater Operations ................. 20

6.4 Sequence of Operation .................................. 20

6.5 Ignition Control Reaction to Air Flow/

Blocked Vent Pressure Switch ....................... 20

6.6 Operating the Burner and Set-Up .................. 21

6.6.1 Set-Up for 0 to 2500 Feet Altitude ................. 21

6.6.2 High Altitude Adjustment and Set-Up............. 22

6.7 Shutting Down the Mighty Stack .................... 22

6.8 To Restart the Mighty Stack ........................... 22

SECTION 7.
Maintenance

7.1 System Maintenance ..................................... 23

7.2 Appliance Maintenance and

Component Description ................................. 23

7.2.1 Burners .......................................................... 23

7.2.2 Filter ............................................................... 23

7.2.3 Gas Valve ...................................................... 23

7.2.4 Manual Reset High Limit Control ................... 24

7.2.5 Ignition Control............................................... 24

7.2.6 Ignitor ............................................................. 24

7.2.7 Transformer ................................................... 24

7.2.8 Flow Switch .................................................... 24

7.2.9 Heat Exchanger Coil ...................................... 24

SECTION 8.
Trouble Shooting

8.1 Resolving Lockouts........................................ 26

8.2 Delayed Ignition – Possible Causes .............. 26

8.3 High Gas Consumption.................................. 26

SECTION 9.
Replacement Parts

9.1 General Information ....................................... 27

9.2 Parts List ........................................................ 27

SECTION 5.
Electrical Connections

5.1 Main Power .................................................... 18

5.2 Field Wiring ................................................... 18

Mighty Stack

Page 3

SECTION 1.
General Information

In the Commonwealth of Massachusetts, this

appliance must be installed by a licensed plumber or

gas tter.

1.1 Introduction

This manual provides information necessary
for the installation, operation, and maintenance of
Laars Heating Systems’ Mighty Stack copper tube

appliances, sizes 199-399 MBTU/hr. Please read
carefully before 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 issues

or questions regarding this equipment. Experience

has shown that most operating issues are caused by

improper installation.

The Mighty Stack appliance is protected against

over pressurization. A pressure relief valve is tted to

the outlet header, at the water outlet of the boiler, and

another near the top of the tank.

IMPORTANT: The inlet gas pressure to the appliance
must not exceed 13 in. w.c. (3.2 kPa).

All installations must be made in accordance with:

1) In the U.S., the " National Fuel Gas Code "ANSI
Z223.1/NFPA54, Latest Edition and all applicable

local codes as required by the Authorities Having
Jurisdiction (AHJ), or

2) In Canada, the "Natural Gas and Propane
Installation Code", CSA B149.1, latest edition and all
applicable local codes as required by the AHJ.

All electrical wiring is to be done in accordance with:

1). In the U.S., the "National Electrical Code" (NEC),
ANSI/NFPA 70, latest Edition and all applicable local

codes as required by the AHJ, or

2). In Canada, the “Canadian Electrical Code - Part
1”, CSA STD. C22.1 and all applicable local codes as
required by the AHJ.

This appliance must be electrically grounded in
accordance with the applicable codes and standards

referenced above.

WARNING

To minimize the risk of electric shock, fire or other
hazards which could result in property damage,
injury, or death. The Mighty Stack hydronic,
water heater or water heater must be installed in
accordance with the procedures detailed in this
manual, or the Laars Heating Systems warranty
may 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 the Natural Gas
and Propane Installation Code, CSA B149.1 and/
or applicable local codes. Where required by
the authority having jurisdiction, the installation
of Mighty Stack appliances must conform to the
Standard for Controls and Safety Devices for
Automatically Fired Water heaters, ANSI/ASME
CSD-1. Any modifications to the water heater, its
gas controls, or wiring may void the warranty. If field
conditions require modifications, consult the factory
representative before initiating such modifications.

AVERTISSEMENT

Afin de réduire au minimum les risques de
commotion électrique, de feu ou d’autre nature,
qui pourraient causer des dommages matériels,
des blessures ou des accidents mortels, les
chaudières à eau chaude ou les chauffe-eau Mighty
Stack doivent être installés conformément aux
directives détaillées contenues dans ce manuel,
à défaut de quoi la garantie fournie par Laars
Heating Systems serait annulée. L’installation doit
être conforme aux exigences de la réglementation
locale en vigueur et, aux États-Unis, à l’édition
la plus récente du Natural Fuel Gas Code (Code
pour le gaz combustible naturel) ANSI Z223.1/
NFPA54. Au Canada, l’installation doit respecter
les exigences de la plus récente édition du Code
d’installation du gaz naturel et du propane CSA
B149.1, et/ou des codes locaux de construction en
vigueur. Lorsque la réglementation locale l’exige,
l’installation des appareils électroménagers Mighty
Stack doit respecter les exigences du Standard
for Controls and Safety Devices for Automatically
Fired Water heaters (Code pour les équipements
de commande et de sécurité des chaudières à
combustion automatique), ANSI/ASME CSD-

1. Toute modification apportée à la chaudière,
aux régulateurs de gaz ou au câblage, peut
compromettre la garantie. Si certaines conditions
particulières rendent des adaptations nécessaires,
consulter un représentant du fabricant avant
d’entreprendre ces modifications.

Page 4

Laars Heating Systems

Model Nomenclature

see Section 1.2 for Model Identification

1 2 3 4 5 6 7 8 9 10 11 12 13

M S 0 8 0 A

SERIES

M S

GALLONS

0 8 0

SIZE

1 9 9

3 0 0

3 9 9

1.2 Model Identication

Consult the rating plate on the unit. The

following information describes the model number

structure.

Model Character Designation

1-2 Model Series Designation

M S = Mighty Stack

3-5 Gallons

080 = 80 Gallons (303 liters)

5-8 Size

1 9 9 = 199,900 BTU/h input
3 0 0 = 299,000 BTU/h input
3 9 9 = 399,900 BTU/h input

9 Fuel

N = Natural Gas
P = Propane

10 Altitude

A = 0-10,000 feet

11 Heat Exchanger / Tank Approvals

2 = HLW Copper Heat Exchanger Only
5 = HLW Cupronickel Heat Exchanger Only
X = HLW (Tank and Copper Heat Exchanger)
Y = HLW (Tank and Cupronickel Heat Exchanger)

12 Pump

N = Normal Water Pump
S = Soft Water Pump

13 Model Revision

1 = Initial Release

1.3 Warranty

Laars Heating Systems’ Mighty Stack appliances

are covered by a limited warranty. The owner should
go to the Laars.com website and register for warranty.

All warranty claims must be made to an

authorized Laars Heating Systems representative or

directly to the factory. Claims must include the 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.

FUEL

N

P

ALTITUDE

A

HEAT

EXCH.

2

5

X

Y

PUMP

OPTIONS

N

S

REVISION

1

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.

1.4 Dimensions

See Figure 1.

1.5 Locating the Appliance

The appliance should be located to provide

clearances on all sides for maintenance and inspection.

It should not be located in an area where leakage of
any connections will result in damage to the area

adjacent to the appliance 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 appliance.

The appliance is design certied by CSA­International for installation on combustible ooring;
in basements; in closets, utility rooms or alcoves.

Mighty Stack Water heaters omust never be
installed on carpeting. The location for the appliance

should be chosen with regard to the vent pipe lengths

and external plumbing. The unit shall be installed

such that the gas ignition system components are

protected from water (dripping, spraying, rain, etc.)

during operation and service (circulator replacement,

control replacement, etc.). When vented vertically, the

Mighty Stack must be located as close as practical to

a chimney or outside wall. If the vent terminal and/

or combustion air terminal terminate through a wall,
and there is potential for snow accumulation in the
local area, both terminals should be installed at an
appropriate level above grade such that blockage of
the terminal from accumulated debris or precipitation

is prevented.

The dimensions and requirements that are shown
in Table 2 should be met when choosing the locations

for the appliance.

Mighty Stack

Page 5

Size A B C D

in. cm in. cm in. cm in. cm

199 33.0 84 4 10 5 13 8.75 22
300 39.0 99 4 10 6 15 15 38
399 43.0 109 6 15 7 18 22 56

*Air and vent connections may be on top or back of the Mighty Stack, and are eld convertible.

Figure 1. Dimensional Data.

Page 6

Laars Heating Systems

1.6 Locating Appliance for Correct
Horizontal Vent/Ducted Air Distance
From Outside Wall

The forced draft combustion air blower in the

appliance has sufcient power to pull air and vent

properly when the guidelines for horizontal air and
vent are followed (see Table 1).

NOTE: When located on the same wall, the
Mighty Stack combustion air intake terminal must
be installed a minimum of 12" (30cm) below the
exhaust vent terminal and separated by a minimum
of 36 inches (91cm) horizontally.

The air intake terminal must be installed high

enough to avoid blockage from snow, leaves and other

debris.

NOTE: On some models, the vent collar size is
larger than the size of the vent pipe that can be
used. Vent collar size and horizontal pipe diameters
can be found in Table 1. The larger vent collar
size is to accommodate Category I (vertical) vent
systems.

Size

199 5 13 4 10 4 10 50 15 3 CA003101 CA003201
300 6 15 5 13 4 10 50 15 3 CA003102 CA003201
399 7 18 6 15 6 15 50 15 3 CA003103 CA003202

Vent Collar

Size

in cm in cm in cm ft m

Horizontal

Vent Pipe

Diameter

Table 1. Horizontal Vent / Combustion Air Parameters.

Intake

Air Collar

& Pipe

Diameter

Max. Pipe

Length

Max. No.

of Elbows

Side Wall

Vent

Terminal

Part Number

Side Wall
Combustion
Air Terminal

Part Number

Appliance

Surface

Left Side 1 2.5 24 61
Right Side 1 2.5 24 61
Top 1 2.5 12 30
Back 1 2.5 **12** **30**
Front 1 2.5 36 91
Vertical

(Category 1)

Vent

Horizontal
(Category 3)
Vent

*1" (2.5 cm) when b-vent is used.
**When vent and/or combustion air connects to the back,
recommended clearance is 36" (91cm).

Required

Clearance From

Combustible Material

inches cm inches cm

*6* *15.2*

per UL 1738 venting
system supplier's
instructions

Table 2. Clearances.

Recommended
Service Access

Clearance

Mighty Stack

Page 7

SECTION 2.
Venting and Combustion Air

WARNING

For indoor installations, as an additional measure
of safety, Laars strongly recommends installation of
suitable Carbon Monoxide detectors in the vicinity of
this appliance and in any adjacent occupied spaces.

AVERTISSEMENT

Pour des installations intérieures, Laars
recommande fortement, comme mesure de sécurité
supplémentaire, l’installation de détecteurs de
monoxyde de carbone adaptés dans le voisinage
de l’appareil et dans chacune des pièces habitées
adjacentes.

2.1 Combustion Air

Mighty Stack water heaters must have provisions
for combustion and ventilation air in accordance with
the applicable sections addressing requirements for air

for combustion and ventilation of the National Fuel
Gas Code, ANSI Z223.1. In Canada, the applicable
sections of the Natural Gas and Propane Installation
Code (CSA B149.1) must be followed. In all cases any

and all applicable local installation codes must also be

followed.

A Mighty Stack appliance may receive
combustion air from the space in which it is installed,

or it can be ducted directly to the unit from the outside.
Proper ventilation air must be provided in either case.

2.1.1 Combustion Air From Room

In the United States, the most common
requirements specify that the space shall communicate
with the outdoors in accordance with method 1 or 2,

which follow. Where ducts are used, they shall be of

the same cross-sectional area as the free area of the

openings to which they connect.

Method 1: Two permanent openings, one

commencing within 12 inches (30 cm) of the top
and one commencing within 12 inches (30 cm) of
the bottom, of the enclosure shall be provided. The

openings shall communicate directly, or by ducts,
with the outdoors or spaces that freely communicate

with the outdoors. When directly communicating

with the outdoors, or when communicating to the
outdoors through vertical ducts, each opening shall

have a minimum free area of 1 square inch per 4000
Btu/hr (5.5 square cm/kW) of total input rating of all
equipment in the enclosure. When communicating to

the outdoors through horizontal ducts, each opening
shall have a minimum free area of not less than

1 square inch per 2000 Btu/hr (11 square cm/kW) of
total input rating of all equipment in the enclosure.

Table 3 shows data for this sizing method, for each

Mighty Stack model.

Method 2: One permanent opening, commencing

within 12 inches (30 cm) of the top of the enclosure,
shall be permitted. The opening shall directly

communicate with the outdoors or shall communicate
through a vertical or horizontal duct to the outdoors
or spaces that directly communicate with the outdoors
and shall have a minimum free area of 1 square inch

per 3000 Btu/hr (7 square cm/kW) of the total input
rating of all equipment located in the enclosure. This

opening must not be less than the sum of the areas of

all vent connectors in the conned space.

Other methods of introducing combustion and
ventilation air are acceptable, providing they conform
to the requirements in the applicable codes listed

above.

In Canada, consult local building and safety
codes or, in absence of such requirements, follow CSA

B149.1, the Natural Gas and Propane Installation Code.

Size

199 50 323
300 75 484
399 100 645

*Net Free Area in Square Inches / Square cm

Area indicated is for one of two openings; one at oor level

and one at the ceiling, so the total net free area could be

double the gures indicated.

This chart is for use when communicating directly with the
outdoors. For special conditions and alternate methods, refer
to the latest edition of ANSI Z223.1.

Note: Check with louver manufacturers for net free area of
louvers. Correct for screen resistance to the net free area
if a screen is installed. Check all local codes applicable to
combustion air.

Table 3. Combustion Air Openings.

Figure 2. Combustion Air and Vent Through Roof.

Square inches Square cm

Each Opening*

Page 8

Laars Heating Systems

2.1.2 Intake Combustion Air

The combustion air can be ducted through the

wall, or through the roof. When taken from the wall, it

must be taken from out-of-doors by means of the Laars
horizontal wall terminal (see Table 1). When taken

from the roof, a eld-supplied rain cap or an elbow

arrangement must be used to prevent entry of rain
water (see Figure 2).

Use single-wall galvanized pipe, per Table

4, for the combustion air intake (see Table 1 for
appropriate size). Route the intake to the heater as
directly as possible. Seal all joints with tape. Provide
adequate hangers. The unit must not support the
weight of the combustion air intake pipe. Maximum
linear pipe length allowed is 50 feet (15.2m). Three
elbows have been calculated into the 50-foot (15.2m)
linear run. Subtract 10 allowable linear feet (3.0m) for
every additional elbow used (see Table 1). When fewer
than 3 elbows are used, the maximum linear pipe
length allowed is still 50 feet (15.2m).

Term Description
Pipe Single-wall galvanized steel pipe, 24 gauge

minimum (either insulated or non-insulated)

Joint Sealing Permanent duct tape or aluminum tape

Table 4. Required Combustion Air Piping Material.

The connection for the intake air pipe is on the

lter box. The Mighty Stack appliances may have

venting and combustion air ducting attached to the top

or the back. They are shipped with the connections
at the top. For attaching either or both pipes to the
back, the mounting anges are reversible by removing
the mounting screws and orienting the anges in the
desired position. Replace the screws after positioning
anges. Run a bead of silicone around the collar and
slide the pipe over the collar. Secure with sheet metal
screws.

In addition to air needed for combustion, air
shall also be supplied for ventilation, including all air
required for comfort and proper working conditions

for personnel. The Mighty Stack loses less than 1

percent of its input rating to the room, but other heat

sources may be present.

2.2 Venting

2.2.1 Vent Categories

Depending upon desired Mighty Stack venting,
it may be considered a Category I or a Category III

appliance. In general, a vertical vent system will be
a Category I system. However, in rare instances, a

Mighty Stack’s vertical vent system may be considered

Category III. In the U.S., the National Fuel Gas Code
(ANSI Z223.1), or in Canada the Natural Gas and
Propane Installation Code (CSA B149.1), denes a

Category I vent system, and includes rules and tables

to size these vent systems. If the Mighty Stack’s

vertical vent system does not satisfy the criteria for
Category I venting, it must be vented as a Category III

system.

All Mighty Stack vent systems which discharge

horizontally (without the use of a power venter) are

considered Category III vent systems.

2.2.2 Category I Vent

When vented as a Category I appliance, the

vent system must conform to the National Fuel Gas
Code (ANSI Z223.1-Latest Edition) in the U.S., or in
Canada, to the Natural Gas and Propane Installation
Code (CSA B149.1 latest edition). The vent system
must be sized and installed for a Category I Fan­Assisted Appliance.

If chimney height is greater than 25 feet (7.6m),

or if multiple units are vented into the same vertical
vent, a barometric damper must be installed on each

appliance, such that the ue draft does not exceed
(negative) 0.1 in. w.c.

If using a power venter for any type of Category

I venting, the draft should be set between (negative)

0.01 and 0.05 in. w.c.

2.2.3 Common Venting Systems

Mighty Stack units are Category I fan-assisted

when vented vertically and adhering to all applicable

codes. Mighty Stack units are not allowed to be

vented into a common horizontal vent system, unless
a properly sized vent fan is used, and the common
vent system is properly designed by the vent fan

manufacturer or a qualied engineer. When common

venting Mighty Stack fan-assisted unit with other
appliances through one shared vertical duct called a

“common vent”, special care must be taken by the
installer to ensure safe operation. In the event that

the common vent is blocked, it is possible, especially
for fan-assisted devices, to vent backwards through
non-operating appliances sharing the vent, allowing

combustion products to inltrate occupied spaces.

If the appliances are allowed to operate in this
condition, serious injury or death may occur.

WARNING

Operation of appliances with a blocked common
vent may lead to serious injury or death. Safety
devices must be implemented to prevent blocked
common vent operation. If safe operation of all
appliances connected to a common vent cannot
be assured, including prevention of spillage of flue
gasses into living spaces, common venting should
not be applied, and appliances should each be
vented separately.

Mighty Stack

Page 9

AVERTISSEMENT

Le fonctionnement d’appareils connectés à un
évent commun bouché peut provoquer de sérieuses
blessures corporelles ou la mort. Des dispositifs de
sécurité doivent être mis en place pour empêcher
que les appareils soient utilisés avec un évent
commun bouché. Si un fonctionnement sécuritaire
de tous les appareils reliés à un évent commun et si
la prévention des dégagements accidentels de gaz
de combustion dans des zones habitées ne peuvent
pas être assurés, un évent commun ne doit pas
être mis en place et les appareils doivent être munis
d’évents individuels séparés.

It is for this reason that, in addition to

following proper vent sizing, construction and safety

requirements from the National Fuel Gas Code,
ANSI Z223.1 or in Canada, from the Natural Gas
and Propane Installation Code (CSA B149.1) as

well as all applicable local codes, it is required that
installers provide some means to prevent operation

with a blocked common vent. It is suggested that a

blocked vent safety system be employed such that if

the switch from one appliance trips due to excessive

stack spill or back pressure indicating a blocked vent
condition, that all appliances attached to the vent be

locked out and prevented from operating. Note that

the Mighty Stack is equipped with a blocked vent

safety (pressure) switch, as shipped. However, this

safety switch has only been designed and tested to
be effective in installations where the Mighty Stack

is vented separately and NOT common vented with
other appliances. As an additional precaution, it is
recommended that a Carbon Monoxide (CO) alarm be

installed in all enclosed spaces containing combustion

appliances. If assistance is required in determining

how a blocked vent safety system should be connected

to a LAARS product, please call Applications
Engineering at the Rochester phone number on the
back cover of this manual.

Refer to the installation and operating

instructions on all appliances to be common vented
for instructions, warnings, restrictions and safety

requirements. If safe operation of all appliances

connected to a common vent cannot be assured,

including prevention of spillage of ue gases into

living spaces, common venting should not be applied,

and appliances should each be vented separately.

2.2.4 Category III Vent

When the Mighty Stack is vented with horizontal
discharge, it must be installed per this installation
manual and the venting system manufacturer’s

installation instructions. The vent system must be
sealed stainless steel, per Table 5.

Route the vent pipe to the heater as directly as
possible. Seal all joints and provide adequate hangers

as required in the venting system manufacturer’s

installation instructions. Horizontal portions of the

venting system must be supported to prevent sagging
and may not have any low sections that could trap

condensate.

The unit must not support the weight of the vent

pipe. Horizontal runs must slope downwards not less

than ¼ inch per foot (2 cm/m) from the unit to the vent

terminal.

L’appareil ne doit pas supporter le poids de la
gaine d’évent. Les parties horizontales doivent être
installées avec une pente de 2 cm/m (1/4 inch par pied)
descendant de l’appareil vers la sortie de l’évent.

Reference Table 1 for the size of the Category
III vent system. Up to three elbows can be used with
50 linear feet (15.2m) of pipe. Subtract 10 allowable
linear feet (3.0m) for every additional elbow used.

2.3 Locating Vent & Combustion Air

Terminals

2.3.1 Side Wall Vent Terminal

The appropriate Laars side wall vent terminal
must be used, and is listed in the installation and

operation manual. The terminal provides a means of

installing the vent piping through the building wall,

and must be located in accordance with ANSI Z223.1/
NFPA 54 and applicable local codes. In Canada, the
installation must be in accordance with CSA B149.1
and local applicable codes. Consider the following

when installing the terminal:

1. Figure 3 shows the requirements for mechanical

vent terminal clearances for the U.S. and Canada.

2. Locate the vent terminal so that vent gases cannot

be drawn into air conditioning system inlets.

3. Locate the vent terminal so that vent gases cannot

enter the building through doors, windows,

gravity inlets or other openings. Whenever

possible, locations under windows or near doors

should be avoided.

4. Locate the vent terminal so that it cannot be

blocked by snow. The installer may determine

that a vent terminal must be higher than the

minimum shown in codes, depending upon local

conditions.

5. Locate the terminal so the vent exhaust does

not settle on building surfaces or other nearby

objects. Vent products may damage such surfaces

or objects.

6. If the water heater or water heater uses ducted

combustion air from an intake terminal located

Term Description

Pipe Must comply with UL Standard 1738 such

as Type AL29-4C Stainless Steel
(either insulated or non-insulated).

Joint

Sealing

Table 5. Required Horizontal Venting Material.

Follow vent manufacturer's instructions.

Page 10

Laars Heating Systems

U.S. Installations (see note 1) Canadian Installations (see note 2)
A= Clearance above grade, veranda, porch, 12 inches (30 cm) 12 inches (30 cm)

deck, or balcony
B= Clearance to window or door that may Direct Vent Only: 12 inches (30 cm)

be opened Other Than Direct Vent: 4 feet (1.2 m) below or 36 inches (91 cm)
to side of opening; 1 foot (30 cm) above opening

C= Clearance to permanently closed window See note 4 See note 5

D= Vertical clearance to ventilated soft located

above the terminal within a horizontal See note 4 See note 5
distance of 2 feet (61cm) from the center line of the terminal

E= Clearance to unventilated soft See note 4 See note 5
F= Clearance to outside corner See note 4 See note 5
G= Clearance to inside corner See note 4 See note 5
H= Clearance to each side of center line See note 4 3 feet (91 cm) within a height 15 feet

extended above meter/regulator assembly above the meter/regulator assembly

I= Clearance to service regulator vent outlet See note 4 3 feet (91 cm)
J= Clearance to non mechanical air supply Direct Vent Only: 12 inches (30 cm)

inlet to building or the combustion air inlet Other Than Direct Vent: 4 feet (1.2 m) below or 36 inches (91 cm)
to any other appliance to side of opening; 1 foot (30 cm) above opening

K= Clearance to a mechanical air supply inlet 3 feet (91 cm) above if within 10 feet (3 m) 6 feet (1.83 m)
horizontally

L= Clearance above paved sidewalk or paved Vent termination not allowed in this location Vent termination not allowed in this
driveway located on public property location

M= Clearance under veranda, porch, deck, See note 4 12 inches (30 cm) (see note 3)
or balcony

Notes:

1. In accordance with the current ANSI Z223.1 / NFPA 54 National Fuel Gas Code.

2. In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code.

3. Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the oor.

4. For clearances not specied in ANSI Z223.1 / NFPA 54, clearance is in accordance with local installation codes and the requirements of

the gas supplier.

5. For clearances not specied in CSA B149.1, clearance is in accordance with local installation codes and the requirements of the gas
supplier.

Figure 3. Vent Terminal Clearance.

Mighty Stack

Page 11

on the same wall, locate the vent terminal at least

3 feet (0.9m) horizontally from the combustion

air terminal, and locate the vent terminal at least

1 foot (0.3m) above the combustion air terminal.

WARNING
The outdoor vent terminal gets hot. Unit must be
installed in such a way as to reduce the risk of
burns from contact with the vent terminal.

AVERTISSEMENT
La sortie d’évent à l’extérieur devient très chaude.
Elle doit être installée de façon à réduire le risque
de brûlures au contact de l’extrémité de l’évent.

Important Note: Massachusetts Code
Requirement.

From Massachusetts Rules and Regulations 248
CMR 5.08:

(a) For all side wall horizontally vented gas

fueled equipment installed in every dwelling,
building or structure used in whole or in
part for residential purposes, including those
owned or operated by the Commonwealth and
where the side wall exhaust vent termination

is less than seven (7) feet above nished grade

in the area of the venting, including but not
limited to decks and porches, the following

requirements shall be satised:

1. INSTALLATION OF CARBON MONOXIDE
DETECTORS.

At the time of installation of the side wall

horizontal vented gas fueled equipment, the

installing plumber or gastter shall observe that
a hard-wired carbon monoxide detector with

an alarm and battery back-up is installed on

the oor level where the gas equipment is to be
installed. In addition, the installing plumber or
gastter shall observe that a battery operated or
hard-wired carbon monoxide detector with an

alarm is installed on each additional level of the
dwelling, building or structure served by the side

wall horizontal vented gas fueled equipment.

It shall be the responsibility of the property

owner to secure the services of qualied licensed

professionals for the installation of hard-wired

carbon monoxide detectors.

a. In the event that the side wall horizontally

vented gas fueled equipment is installed
in a crawl space or an attic, the hard-wired

carbon monoxide detector with alarm and
battery back-up may be installed on the next
adjacent oor level.

b. In the event that the requirements of this

subdivision cannot be met at the time of

completion of installation, the owner shall

have a period of thirty (30) days to comply
with the above requirements; provided,
however, that during said thirty (30) day
period, a battery operated carbon monoxide
detector with an alarm shall be installed.

2. APPROVED CARBON MONOXIDE
DETECTORS.

Each carbon monoxide detector as required

in accordance with the above provisions shall

comply with NFPA 720 and be ANSI/UL 2034
listed and IAS certied.

3. SIGNAGE.

A metal or plastic identication plate shall be

permanently mounted to the exterior of the

building at a minimum height of eight (8) feet

above grade directly in line with the exhaust vent

terminal for the horizontally vented gas fueled

heating appliance or equipment. The sign shall

read, in print size no less than one-half (½) inch

in size, “GAS VENT DIRECTLY BELOW.
KEEP CLEAR OF ALL OBSTRUCTIONS”.

4. INSPECTION.

The state or local gas inspector of the side

wall horizontally vented gas fueled equipment
shall not approve the installation unless, upon
inspection, the inspector observes carbon

monoxide detectors and signage installed in
accordance with the provisions of 248 CMR

5.08(2)(a) 1 through 4.

(b) EXEMPTIONS: The following equipment is

exempt from 248 CMR 5.08(2)(a) 1 through 4:

1. The equipment listed in Chapter 10 entitled
“Equipment Not Required To Be Vented” in the
most current edition of NFPA 54 as adopted by
the Board; and

2. Product Approved side wall horizontal vented gas

fueled equipment installed in a room or structure
separate from the dwelling, building or structure

used in whole or in part for residential purposes.

(c) MANUFACTURER REQUIREMENTS –

GAS EQUIPMENT VENTING SYSTEM
PROVIDED. When the manufacturer of
Product Approved side wall horizontally vented
gas equipment provides a venting system
design or venting system components with the
equipment, the instructions provided by the
manufacturer for installation of the equipment

and the venting system shall include:

1. Detailed instructions for the installation of the

venting system design or the venting system

components; and

Page 12

Laars Heating Systems

2. A complete parts list for the venting system
design or venting system.

(d) MANUFACTURER REQUIREMENTS –

GAS EQUIPMENT VENTING SYSTEM
NOT PROVIDED. When the manufacturer
of a Product Approved side wall horizontally
vented gas fueled equipment does not
provide the parts for venting the fuel gases,

but identies “special venting systems”, the
following requirements shall be satised by
the manufacturer:

1. The referenced “special venting system”

instructions shall be included with the appliance

or equipment installation instructions; and

2. The “special venting systems” shall be Product

Approved by the Board, and the instructions for
that system shall include a parts list and detailed

installation instructions.

(e) A copy of all installation instructions for all

Product Approved side wall horizontally
vented gas fueled equipment, all venting
instructions, all parts lists for venting
instructions, and/or all venting design
instructions shall remain with the appliance
or equipment at the completion of the
installation.

2.3.2 Side Wall Combustion Air Terminal

The Laars side wall combustion air terminal

(listed in Table 1) must be used when the unit takes

its combustion air through a duct from a side wall.

Consider the following when installing the terminal:

1. Do not locate the air inlet terminal near a source
of corrosive chemical fumes (e.g., cleaning uid,
chlorinated compounds, etc.)

2. Locate the terminal so that it will not be subject
to damage by accident or vandalism.

3. Locate the combustion air terminal so that it
cannot be blocked by snow. The National Fuel
Gas Code requires that it be at least 12 inches (30

cm) above grade, but the installer may determine
it should be higher, depending upon local

conditions.

4. If the Mighty Stack is side-wall vented to the

same wall, locate the vent terminal at least 3

feet (0.9m) horizontally from the combustion air

terminal, and locate the vent terminal at least 1

foot (0.3m) above the combustion air terminal
(see Figure 3).

2.3.3 Vertical Vent Terminal

When the unit is vented through the roof, the

vent must extend at least 3 feet (0.9m) above the point
at which it penetrates the roof. It must extend at least
2 feet (0.6m) higher than any portion of a building

within a horizontal distance of 10 feet (3.0m), and high

enough above the roof line to prevent blockage from

snow. When the combustion air is taken from the roof,
the combustion air must terminate at least 12" (30cm)
below the vent terminal (see Figure 2).

2.3.4 Vertical Combustion Air Terminal

When combustion air is taken from the roof, a

eld-supplied rain cap or an elbow arrangement must

be used to prevent entry of rain water (see Figure 2).
The opening on the end of the terminal must be at least

12" (30cm) above the point at which it penetrates the

roof, and high enough above the roof line to prevent

blockage from snow. When the vent terminates on the
roof, the combustion air must terminate at least 12"
(30cm) below the vent terminal.

2.4 Common Vent Test — Water Heaters

When an existing water heater is removed from a

common venting system, the common venting system
is likely to be too large for proper venting of the

appliances remaining connected to it.

At the time of removal of an existing water

heater, the following steps shall be followed with each
appliance remaining connected to the common venting
system placed in operation, while the other appliances
remaining connected to the common venting system

are not in operation.

1. Seal any unused openings in the common venting
system.

2. Visually inspect the venting system for proper

size and horizontal pitch and determine there is
non blockage or restriction, leakage, corrosion

and other deciencies which could cause an
unsafe condition.

3. Insofar as it is practical, close all building doors

and windows and all doors between the space in
which the appliances remaining connected to the
common venting system are located and other

spaces of the building. Turn on clothes dryers

and any appliance not connected to the common

venting system. Turn on any exhaust fans, such
as range hoods and bathroom exhausts, so they
will operate at maximum speed. Do not operate a
summer exhaust fan. Close replace dampers.

4. Place in operation the appliance being
inspected. Follow the lighting instructions.

Adjust thermostat so appliance will operate

continuously.

5. Test for spillage at the draft hood relief opening
after 5 minutes of main burner operation. Use
the ame of a match or candle, or smoke from a
cigarette, cigar or pipe.

6. After it has been determined that each appliance

remaining connected to the common venting
system properly vents when tested as outlined

above, return doors, windows, exhaust fans,
replace dampers and any other gas burning

Mighty Stack

Page 13

appliance to their previous conditions of use.

7. Any improper operation of the common venting

system should be corrected so that the installation

conforms with the National Fuel Gas Code,
ANSI Z223.1/NFPA 54 and/or CSA B149.1,
Natural Gas and Propane Installation Codes.

When resizing any portion of the common
venting system, the common venting system
should be resized to approach the minimum size
as determined using the appropriate tables in

Appendix F in the National Fuel Gas Code, ANSI
Z223.1/NFPA 54 and/or CSA B149.1, Natural
Gas and Propane Installation Codes.

2.4 Véricationdeséventscommuns—
Chaudières

Lorsqu’une chaudière existante est déconnectée

du réseau d’évents commun, ce réseau d’évents
commun devient probablement trop grand pour
les appareils qui lui restent connectés. Lorsqu’une
chaudière existante est retirée, les étapes suivantes
doivent être accomplies pour chaque appareil qui
reste connecté au réseau d’évents commun utilisé,
alors que les autres appareils qui sont encore
connectés au réseau commun d’évents ne sont pas en
fonctionnement.:

1. Sceller toutes les ouvertures non utilisées du
système d'évacuation.

2. Inspecter de façon visuelle le système
d'évacuation pour déterminer la grosseur et
l'inclinaison horizontale qui conviennent et
s'assurer que le système est exempt d'obstruction,
d'étranglement, de fuite, de corrosion et autres
défaillances qui pourraient présenter des risques.

3. Dans la mesure du possible, fermer toutes les
portes et les fenêtres du bâtiment et toutes les
portes entre l'espace où les appareils toujours
raccordés au système d'évacuation sont installés
et les autres espaces du bâtiment. Mettre en
marche les sécheuses, tous les appareils non
raccordés au système d'évacuation common
et tous les ventilateurs d'extraction comme
les hottes de cuisinière et les ventilateurs des
salles de bain. S'assurer que ces ventilateurs
fonctionnent à la vitesse maximale. Ne pas faire
fonctionner les ventilateurs d'été. Fermer les
registres des cheminées.

4. Mettre l'appareil inspecté en marche. Suivre les
instructions d'allumage. Réegler le thermostat de
façon continue.

5. Faire fonctionner le brûleur principal pendant
5 min ensuite, déterminer si le coupe-tirage
déborde à l'ouverture de décharge. Utiliser la

amme d'une allumette ou d'une chandelle ou la

fumée d'une cigarette, d'un cigare ou d'une pipe.

6. Une fois qu'il a été déterminé, selon la méthode
indiquée ci-dessus, que chaque appareil
raccordé au système d'évacuation est mis à l'air

libre de façon adéquate. Remettre les portes
et les fenêtres, les ventilateurs, les registres de
cheminées et les appareils au gaz à leur position
originale.

7. Tout mauvais fonctionnement du système
d'évacuation commun devrait être corrigé
de façon que l'installation soit conforme au
National Fuel Gas Code, ANSI Z223.1/NFPA
54 et (ou) aux codes d'installation CSA-B149.1.
Si la grosseur d'une section du système devrait

être modié, le système devrait être modié pour

respecter les valeurs minimales des tableaux
pertinents de l'appendice F du National Fuel Gas
Code, ANSI Z223.1/NFPA 54 et (ou) les codes
d'installation CSA-B149.1

2.5 Vent Terminals for Outdoor Units

For outdoor applications, the vent and

combustion air openings must be covered with proper
terminals to prevent rain, snow and other objects from

falling into the Mighty Stack.

Outdoor Vent / Air kit part numbers are shown in

Table 6. These kits contain parts for both combustion
air inlet and exhaust vent connections. An angled sheet

metal assembly with louvers replaces the sheet metal

assembly with the air collar. An adapter, a 12" (30cm)

length of pipe, and a rain cap are included for the

exhaust vent opening.

If local codes allow, Laars kits are not required

for outdoor units. The installer may use 12" (30cm) of

appropriately sized galvanized single wall or b-type

vent pipe and a rain cap for the exhaust vent. In
addition, an appropriately sized galvanized 90° elbow,

positioned with the opening facing down, may be used

on the combustion air inlet.

Size

199 CA009000
300 CA009001
399 CA009002

Table 6. Vent / Air Kits for Outdoor Units.

Outdoor Vent and

Air Terminal Kit

Page 14

Laars Heating Systems

Figure 4. Venting.

Mighty Stack

Page 15

SECTION 3.
Gas Supply and Piping

3.1 Gas Supply and Piping

Gas piping should be supported by suitable

hangers or oor stands, not by the appliance.

The Mighty Stack’s gas train allows the user to

pipe the gas from either the right side or the left side

of the unit. As shipped, the right side of the gas train is
capped off, and there is a manual valve on the left side.

If desired, the manual valve on the left side of the gas
train may be moved to the right side, and the cap on

the right side may be moved to the left.

Review the following instructions before

proceeding with the installation.

1. Verify that the appliance is tted for the proper
type of gas by checking the rating plate. Mighty

Stack appliances are equipped to operate at

elevations up to 10,000 feet (3050m). Mighty

Stack appliances may be adjusted to operate

properly at altitudes above 2500 feet (see Section

6.5.2) and the input will be reduced if the heating
value of the gas supply is below sea level values.

2. The maximum inlet gas pressure must not
exceed 13" w.c. (3.2kPa). The minimum inlet gas
pressure is 5 in. w.c. (1.2 kPa).

3. Refer to Table 7, size supply.

4. Run gas supply line in accordance with all
applicable codes.

5. Locate and install manual shutoff valves in
accordance with state and local requirements.

6. A sediment trap must be provided upstream of
the gas controls.

7. All threaded joints should be coated with
piping compound resistant to action of liqueed
petroleum gas.

8. The appliance and its individual shutoff valve

must be disconnected from the gas supply piping
during any pressure testing of that system at test

pressures in excess of 0.5 psig (3.45 kpa).

9. The unit must be isolated from the gas supply

system by closing its individual manual shutoff
valve during any pressure testing of the gas
supply piping system at test pressures equal to or

less than 0.5 psig (3.45 kpa).

10. The appliance and its gas connection must be
leak tested before placing it in operation.

11. Purge all air from gas lines.

WARNING

Do not use open flame to check for leaks. An open
flame could lead to explosion, which could result in
property damage, serious injury or death.

AVERTISSEMENT

Ne recherchez pas les fuites avec une flamme nue.
Une flamme nue peut provoquer une explosion qui
peut causer des dommages matériels, de sérieuses
blessures corporelles ou la mort.

NOTE: The Mighty Stack appliance and all other
gas appliances sharing the gas supply line must
be firing at maximum capacity to properly measure
the inlet supply pressure. The pressure can be
measured at the supply pressure port on the gas
valve. Low gas pressure could be an indication of
an undersized gas meter, undersized gas supply
lines and/or an obstructed gas supply line.

Model and

Gas Type

199 natural 1¼" 3.2 cm 1¼" 3.2 cm 1¼" 3.2 cm

199 propane 1" 2.5 cm 1" 2.5 cm 1¼" 3.2 cm

300 natural 1¼" 3.2 cm 1½" 4.0 cm 1½" 4.0 cm

300 propane 1 2.5 cm 1¼" 3.2 cm 1¼" 3.2 cm

399 natural 1¼" 3.2 cm 1½" 4.0 cm 2" 5.0 cm

399 propane 1¼" 3.2 cm 1¼" 3.2 cm 1½" 4.0 cm

Notes:

1. These gures are based on 1/2" (0.12 kPa) water column pressure drop.

2. Check supply pressure and local code requirements before proceeding with work.

3. Pipe ttings must be considered when determining gas pipe sizing.

0-100'

Distance from Gas Meter or Last Stage Regulator

0-31 m 100-200' 31-61m 200-300' 61-91m

Table 7. Gas Piping Size.

Page 16

Laars Heating Systems

SECTION 4.
Water Connections

4.1 Water System Piping

Pipe the outlet from the heater’s relief valves

such that any discharge from the 2 relief valves will be
conducted to a suitable place for disposal when relief

occurs. Do not reduce line size or install any valves in
this line. The lines must be installed to allow complete

drainage of both the valve and the line (see Figure 4).

The minimum inlet water temperature for the

Mighty Stack is 120°F (49°C) to avoid condensing on
the copper coils. It is the responsibility of the installer
to properly mix supply water as necessary to keep the
return water temperature above 120°F.

NOTE: Laars will not warranty claims for failure to
provide minimum return water temperature.

4.2 Hot Water Supply Piping

If the Mighty Stack water heater is installed in

a closed water supply system, such as one having a

backow preventer in the cold water supply line, the

relief valve may discharge periodically, due to thermal

expansion. Means (such as a properly-sized expansion
tank) shall be provided to control thermal expansion.

Contact the water supplier or local plumbing inspector

on how to control this situation.

4.3 Water Flow Requirements

In a water heating application, new water is

constantly being introduced. With the new water

comes a fresh supply of minerals that can be deposited

on the unit’s heat exchanger. This is commonly known
as scaling. The amount of minerals will depend
upon the hardness of the water. Water can also be

aggressive, and can erode metals, including copper,

if the water is moved too quickly. The water ow

requirements for the Mighty Stack water heater are

based upon the hardness of the water. The water ow

is kept high enough to prevent scaling, but low enough

to prevent tube erosion. For extremely soft or hard
water, cupro-nickel tubes are available. Contact a

Laars representative if you have questions or concerns

about water quality.

Water heaters can be ordered with a standard

pump for soft or normal water or with a pump for

hard water. The pumps used are sized for the head loss
through the heater.

4.4 Combined Water Heating (potable)
and Space Heating

NOTE: These systems are not allowed in the

Commonwealth of Massachusetts.

Piping and components connected to this water

heater shall be suitable for use with potable water.

Toxic chemicals, such as used for water heater

treatment, shall not be introduced into the potable

water used for space heating.

This water heater shall not be connected to any

heating system or component(s) previously used with a

non-potable water heating appliance.

When the system requires water for heating at

temperatures higher than required for other uses,
an anti-scald mixing or tempering valve shall be
installed to temper the water for those uses in order
to reduce scald hazard potential.

4.5 Freeze Protection

Although Mighty Stack water heaters are design-

certied for outdoor installations, such installations

are not recommended in areas subject to freezing

temperatures, unless proper precautions are taken.

Power outage, interruption of gas supply, failure

of system components, activation of safety devices,

etc., may prevent a heater from ring. Any time a
heater is subjected to freezing conditions, and the

heater is not able to re, and/or the water is not

able to circulate, there is a risk of freezing in the
heater or in the pipes in the system. When water

freezes, it expands. This can result in bursting of pipes

in the system, or damage to the heater, which could

result in leaking or ooding conditions.

Contact the local factory representative or Laars

for additional information.

Mighty Stack

Page 17

Figure 4. Suggested Plumbing.

Figure 5. Suggested Plumbing, Three Units (in rst, out last).

Page 18

SECTION 5.
Electrical Connections

WARNING

The appliance must be electrically grounded in
accordance with the requirements of the authority
having jurisdiction or, in the absence of such
requirements, with the latest edition of the National
Electrical Code, ANSI/NFPA 70, in the U.S. and
with latest edition of CSA C22.1 Canadian Electrical
Code, Part 1, in Canada. Do not rely on the gas
or water piping to ground the metal parts of the
water heater. Plastic pipe or dielectric unions may
isolate the water heater electrically. Service and
maintenance personnel, who work on or around
the water heater, may be standing on wet floors
and could be electrocuted by an ungrounded water
heater.

AVERTISSEMENT

L’appareil doit être relié à la terre conformément
aux exigences de la réglementation locale ou,
en l’absence d’une telle réglementation, à la plus
récente édition du National Electrical Code (Code
national de l’électricité) ANSI/NFPA 70 aux États­Unis, et à la plus récente édition du Code Canadien
de l’électricité 1
Code Part 1) CSA C22.1, au Canada. N’utilisez
pas les tuyauteries d’eau ou de gaz pour mettre
à la terre les pièces métalliques de la chaudière;
des tuyauteries en plastique ou des raccords
union diélectriques peuvent isoler électriquement
la chaudière. Les employés qui sont appelés à
travailler sur la chaudière ou autour peuvent être
électrocutés par une chaudière qui n’est pas mise à
la terre.

ère

partie (Canadian Electrical

Laars Heating Systems

Single pole switches, including those of safety

controls and protective devices must not be wired in a

grounded line.

NOTE: All internal electrical components have been pre­wired. No attempt should be made to connect electrical
wires to any other location except the wiring box.

5.1 Main Power

Connect a 15 amp. fused, 120-volt supply to

the main power switch. Both hot and neutral wires

are provided for connections inside the water heater

jacket. Ground wire can be connected to the grounding
screw in the box.

Wiring diagram is shown in Figure 7.

5.2 Field Wiring

Other Field Interlocks: To install other eld­wired switches (proving switches, ow switches, etc.),
remove the jumper between the terminals labeled “3”
and “4” (see Figure 6).

Figure 6. Terminal Block.

Mighty Stack

Page 19

Figure 7. Wiring Diagram, ON/OFF Water Heater.

Page 20

Laars Heating Systems

SECTION 6.
Operating Instructions

6.1 Filling the Water Heater System

1. Ensure the system is fully connected. Allow
system to ll slowly.

2. Start up water heater according to the procedure
in this manual.

3. After placing the unit in operation, the ignition
system safety shutoff device must be tested.
First, shut off the manual gas valve, and call
the unit for heat. After the pre-purge and ignitor

heat-up time, the main gas terminals will be

energized, attempting to light, for seven (7)
seconds, and then will de-energize. The unit will

attempt to light two more times, and then will go

into lockout mode. Second, turn the power off

and then on again, open the manual gas valve

and allow the unit to light. While the unit is

operating, close the manual gas valve and ensure

that power to the main gas valve has been cut.

Important: The installer is responsible for identifying
to the owner/operator the location of all emergency
shutoff devices.

WARNING

Do not use this appliance if any part has been
under water. Immediately call a qualified service
technician to inspect the appliance and to replace
any part of the control system and any gas control
that may have been under water.

AVERTISSEMENT

N’utilisez pas cet appareil si l’une de ses pièces est
passée sous l’eau. Appelez tout de suite un technicien
en entretien et en réparation pour inspection de
l’appareil et remplacement des pièces du système de
commande, et des pièces de commande du circuit
gaz, qui sont passées sous l’eau.

6.2 Operating Temperature Control

To utilize the water heater's on-board controller,

be sure to have the “Local/Remote” selector switch to
“Local”. Set the controller to the desired operating set
point.

High limit should be set 40-50°F (4-10°C) higher

than the controller, to avoid nuisance lockout of the

manual reset high limit.

Maximum tank temp. allowed is 150°F (66°C).

6.3 External Water Heater Operations

If controlling the stages of the MS-080 from

an external source (multiple water heater control,
BAS, etc) the “Local/Remote” selector switch above
the terminal strip must be placed in the “Remote”
position. In this mode, the controller that is mounted

on the MS-080 will no longer have control of the unit.
The 24V from the unit waits at the input terminal, and
the external control switches this 24V from the input.

6.4 Sequence of Operation

The pump time delay relay will receive a signal

to initiate. The pump terminals on the eld-wiring
terminals strip will energize a pump.

Once the water ow switch makes, if all of the

safety interlocks are closed, the ignition module

will energize the blower for a 15-second pre-purge,
followed by a 40-second period to allow the ignitor to
heat.

The ignition control energizes the blower. The

blower pressurizes the air box (which supplies air to

the burners) and closes the normally-open contact

on the airow pressure switch. The blocked vent
pressure switch senses the pressure in the exhaust
plenum. This switch opens if the pressure is excessive
(as an indicator of a blocked vent). When these two

pressure switches are closed, voltage is sent to the

PSW terminal on the ignition control, which allows the
ignition module to proceed with the ignition sequence.

If the airow proving circuit is not proven,
ignition module will lock out. Section 6.5 describes
the result of air ow faults in more detail.

When the ignition control gets the signal at the

PSW terminal, it will energize its MV terminal, which
sends power to the main valve.

After a 7-second trial for ignition, the ignitor
switches to ame sense mode. If a ame is not

detected, the gas valve will close and the ignition
module will attempt ignition again (up to two more

times, for a total of three attempts.) If all three
attempts fail, the ignition control will lock out.

If ame is sensed, the burner will continue to
re as long as there is a call for heat, and none of the
safety circuit is interrupted.

If there is a loss of ame signal during a
successful ring sequence, the ignition control will

remove power from the gas valve, and then attempt to

light up to two more times. If successful, the Mighty
Stack will re normally. If unsuccessful, the ignition
control will lock out.

When the call for heat is satised, the gas
valve(s) closes, and the blower starts a 45 second post­purge. The Mighty Stack pump time delay relay will

continue to run for the time delay period (dialed by the

user, 0.1 to 10 minutes).

6.5 Ignition Control Reaction to Air Flow /

Blocked Vent Pressure Switch

Air ow and blocked vent status are continuously

monitored by the Mighty Stack ignition control, at the

control’s PSW terminal.

At the start of an ignition sequence, if the ignition

control sees power at PSW for 30 seconds, but the

combustion blower has not yet been energized by the

Mighty Stack

Figure 8. Logic Diagram, ON/OFF Water Heater.

control (F1 and F2). The ignition control will remain
in this fault mode, with the blower off. If the power to
PSW is removed while there is still a call for heat, the

ignition sequence will start again, but the main valves

will not be energized until PSW sees power during the
ignition sequence.

At the start of an ignition sequence, the control

sends the combustion blower output (F1 and F2). If
the control does not see power at PSW for more than
30 seconds, the control will remain in this fault mode,
with the blower on. If proper airow is later detected

Page 21

on PSW, the control begins a pre-purge and a normal
trial for ignition.

If the PSW signal is lost while the Mighty Stack
is ring, the control will immediately de-energize the
gas valve terminal (MV). The blower will remain on
for the post-purge period (45 seconds), and the control
will continue to monitor the PSW input. If the signal

is detected during the post-purge period, a normal trial

for ignition will begin, starting with the 15-second
pre-purge. If the signal is not detected during the post­purge, the control will lockout with the blower off.

6.6 Operating the Burner and Set-Up

6.6.1 Set-Up for 0 to 2500 Feet Altitude

The setup must be checked before the unit is put in

operation. Problems such as failure to start, rough igni­tion, strong exhaust odors, etc. can be due to improper
setup. Damage to the Mighty Stack resulting from
improper setup is not covered by the limited warranty.

1. Using this manual, make sure the installation

is complete and fully in compliance with the

instructions.

2. Determine that the appliance and system are

lled with water and all air has been bled from

both. Open all valves.

3. Observe all warnings on the Operating

Instructions label and turn on gas and electrical

power to appliance.

4. Switch on the appliance power switch located on

the right side of the unit.

5. The Mighty Stack will enter the start sequence,

as long as the unit is being called for heat. The

blower and pump come on for pre-purge, then

the ignitor warm-up sequence starts and after

the ignitor warm-up is complete and all safety

devices are veried, the gas valves open. If

ignition doesn’t occur, check that there is proper

gas supply. Wait 5 minutes and start the unit

again. During initial start up, air in the gas line

may cause the Mighty Stack to "lock out" during

the rst few trials for ignition. If the ignition

control locks out, reset by cycling the power off

and on using the main power switch on the right

side of the cabinet.

6. When the unit is running, the supply gas pressure

must be checked. Inlet gas pressure must not

exceed 13 in. w.c. (3.2 kPa). The minimum inlet

gas pressure is 5 in. w.c. (1.2 kPa) and 8 in. w.c.

(2 kPa) for LP.

7. Once the inlet gas pressure is veried, the outlet

gas pressure (manifold gas pressure) must be

checked, and adjusted, if necessary. The manifold

gas pressure must be 3.0 in. w.c. (0.62 kPa) for

natural gas and 9.0 in. w.c. (2.2 kPa) for LP.

8. Complete the setup by checking the CO

outlet of the unit. The CO

should be 8% for

2

natural gas, or 9.2% for LP.

at the

2

Page 22

Laars Heating Systems

9. After placing the appliance in operation, the

Burner Safety Shutoff Device must be tested.

To test:

(a) Close gas shutoff valve with burner

operating.

(b) The ame will go out and blower will

continue to run for the post purge cycle.
Three attempts to light will follow. Ignition
will not occur as the gas is off. The ignition

control will lockout, and will have to be
reset by cycling the power before the unit

will operate.

(c) Open gas shutoff valve. Restart the

appliance. The ignition sequence will
start again and the burner will start. The

appliance will return to its previous mode

of operation.

6.6.2 High Altitude Adjustment and
Set-Up

High altitude adjustment must not be made on

appliances operating at elevations below 2500 ft. (762 m).

No orice changes are required to adjust the

Mighty Stack appliances for high altitude. High

altitude adjustment is accomplished by adjustment

of the air shutter. A CO

or O2 analyzer is required to

2

make these adjustments.

Start the adjustment process by checking the CO

in the “as installed” condition. Adjust the air shutter(s)

so that the CO

is about 8% or the O2 is about 6.8%

2

for appliances operating on natural gas. For appliances
operating on LP Gas adjust the air shutter(s) so that the

is about 9.2% or the O2 is about 6.8%.

CO

2

If the appropriate CO

/ O2 levels cannot be

2

achieved by adjusting the air shutter. Contact the

Technical Services Department at number shown on

back page.

The amount of derate will vary depending on

heating value of the fuel and the elevation at the

installation site.

6.7 Shutting Down the Mighty Stack

1. Switch off the main electrical disconnect switch.

2. Close all manual gas valves.

3. If freezing is anticipated, drain the Mighty Stack

and be sure to also protect building piping from

freezing.

This step to be performed by a qualied

service person.

6.8 To Restart the Mighty Stack

If drained, follow Section 6.1 in this manual for

proper lling and purging.

1. Switch off the main electrical disconnect switch.

2. Close all manual gas valves.

3. WAIT FIVE (5) MINUTES.

4. Set the aquastat or thermostat to its lowest
setting.

5. Open all manual gas valves.

6. Reset all safety switches (pressure switch,
manual reset high limit, etc.).

7. Set the temperature controller to the desired

temperature setting and switch on electrical

power.

8. Burner will go through a pre-purge period and
ignitor warm-up period, followed by ignition.

2

Caution

Should any odor of gas be detected, or if the gas
burner does not appear to be functioning in a
normal manner, close main shutoff valve, do not
shut off switch, and contact your heating contractor,
gas company, or factory representative.

Attention

Si vous sentez une odeur de gaz ou si le brûleur
à gaz ne parait pas fonctionner de manière
normale, fermez la vanne d’isolement, ne fermez
aucun interrupteur, et appelez votre entreprise de
chauffage, la compagnie de gaz ou un représentant
du fabricant.

Mighty Stack

Page 23

SECTION 7.
Maintenance

7.1 System Maintenance

1. Lubricate the system water-circulating pump, if
required, per the instructions on the pump.

2. If a strainer is employed in a pressure reducing
valve or the piping, clean it every six months.

3. Inspect the venting system for obstruction or
leakage at least once a year. Periodically clean

the screens in the vent terminal and combustion

air terminal (when used).

4. Keep the appliance area clear and free from

combustible materials, gasoline, and other

ammable vapors and liquids.

5. If the appliance is not going to be used for
extended periods in locations where freezing

normally occurs, it should be isolated from the

system and completely drained of all water. All

systems connected to it should also be drained or

protected from freezing.

6. Low water cutoffs, if installed, should be
checked every 6 months. Float type low water
cutoff should be ushed periodically.

7. Inspect ue passages, and clean with brushes/
vacuums, if necessary. Sooting in ue passages
indicates improper combustion. Determine the
cause and correct.

8. Inspect the vent system and air intake system,

and if the vent system is Category III, ensure

that all joints are sealed properly. If joints need

to be resealed, follow venting manufacturer's

instructions to clean and reseal vent system.

7.2 Appliance Maintenance and
Component Description

Only genuine Laars replacement parts should be used.

Caution

Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and
dangerous operation. Verify proper operation after
servicing.

Attention

Lors d’entretien ou de réparation des commandes,
étiquetez tous les câbles avant de les déconnecter.
Des erreurs de câblage peuvent provoquer des
fonctionnements incorrects et dangereux. Après
toute intervention d’entretien ou de réparation,
vérifier que l’appareil fonctionne correctement.

The gas and electric controls on the appliance

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

proper functioning. It is strongly recommended that

a qualied service technician inspect the basic items
listed below every year.
a. Ignition control
b. Ignitor
c. Water temperature control
d. Automatic gas valve
e. Pressure switches and tubing
f. Blower
g. High limit
h. Pump
i. Relays
j. Flow switch
k. Gas train
l. Control components

7.2.1 Burners

Close main manual gas valve before proceeding.

Checking the burners for debris - Remove the ignitor/

burner access panel and ignitor, and inspect the

burners through the ignitor hole using a ashlight to
illuminate. If there is any indication of debris on the

burners that is visible, all the burners will need to be

inspected more thoroughly. Remove the gas manifold
assemblies and the burner assemblies. Inspect the
burners. Clean burners, if necessary, by blowing

compressed air from the outside of the burners into

the center of the burner. A dirty burner may be an

indication of improper combustion or dirty combustion

air. Determine the cause, and correct. Replace the
burners in the reverse order.

7.2.2 Filter

The lter used in the Mighty Stack is washable
and has an 80% arrestance rating. Since the lter is
washable, it will only need replacement occasionally.
If lter replacement is needed, it should only be
replaced with a factory part. Inspect the air lter
monthly, or more often in dirty environments. If there
is debris on the air lter, remove it from the lter
frame, and wash it with mild soap and water. Ensure
that the lter is completely dry before reinstalling.

7.2.3 Gas Valve

The gas valve is designed to operate with supply

pressures of 4-13 in. w.c. (1.0 to 3.2 kPa).

To remove a valve, shut off 120-volt power
and the manual gas shutoff valve. Remove the front
panels from the unit. Disconnect the wires to the valve.

Disengage the unions before and after the valve, and

remove the valve. Pull the pipe nipples from the inlet

and outlet of the valve, and clean the threads on the

pipe nipples for reuse. Apply new tape or pipe dope

to the pipe nipples (threaded joints should be coated

with piping compound resistant to action of liqueed
petroleum gas), and reinstall in reverse order. Turn
on manual gas shutoff valve and 120 volt power and

check appliance operation and tightness of gas valve

connections.

Page 24

Laars Heating Systems

7.2.4 Manual Reset High Limit Control

The high limit switch is a manual reset, non-

adjustable switch with a remote bulb-type sensor.
Switches are set at 200°F (93°C).The control is located
behind the front door, on a panel in front of the blower.
The probe is in the outlet side of the header.

To reset the switch, unscrew the black cover that

is over the reset button, and push the button. Replace
the cover after the switch is reset.

To replace, shut off power to the appliance.
Remove the cover that is over the button, and remove
the nut that is around the button. Pull the control
through the panel, and remove the spade terminals.
Replace in reverse order.

7.2.5 Ignition Control

The ignition control controls the hot surface

ignitor and proves that the ame signal is appropriate
for powering the gas valves. It also controls the
blower’s pre-purge and post-purge.

To replace a control, shut off the 120-volt power
to the appliance. Remove the cover from the control
panel. Remove the electrical connectors from the
ignition control. Take out the controller’s mounting
screws, and pull the controller out. Replace in reverse
order.

7.2.6 Ignitor

The ignitor used is a 120v “Hot Surface” type.

It is energized whenever there is a call for heat and

switched off when ignition is established and the ame
has been sensed. To replace the ignitor, shut off the
120-volt power to the appliance, remove the ignitor/
burner access panel, disconnect the Molex connector,
remove the two mounting screws on the ignitor ange,
and pull the ignitor out. Install in reverse order, always

using a new ignitor gasket with the replacement

ignitor.

Caution

Ignitor gets hot. To avoid injury, handle the ignitor
with caution.

Attention

Le dispositif d’allumage devient très chaud.
Manipulez le dispositif d’allumage avec précaution.

7.2.7 Transformer

The Mighty Stack’s transformer is not capable of

supplying control voltage for external devices, which
must have their own separate power supply. Should
a transformer need replacing, shut off the 120-volt
power. Unplug the transformer wires, remove the
mounting screws and remove the transformer. Replace
transformer in the reverse order.

7.2.8 Flow Switch

The Mighty Stack uses a paddle-type ow switch
to ensure that the unit has water ow before ignition is
allowed. To replace the ow switch, turn off the 120­volt power to the appliance. Isolate the water heater or

water heater from the system by closing the isolation

valves.

Caution

Water may be hot enough to scald. Allow water to
cool before proceeding.

Attention

L’eau peut être chaude au point de vous brûler.
Laissez refroidir l’eau avant d’intervenir.

Release pressure in the system by actuating the
pressure relief valves or eld supplied water heater
drain valve. Remove cover from the ow switch
and disconnect the wires. Unthread the ow switch
from piping. Ensure the new ow switch paddles

are trimmed to the same size as the original paddles,

and reinstall in the reverse order. For water heater

and other static pressure systems, restore the system

pressure to the original setting, (or 10 psi minimum).

7.2.9 Heat Exchanger Coil

WARNING

Black carbon soot buildup on a dirty heat exchanger
can be ignited by a random spark or flame thereby
creating a risk of fire or explosion. To prevent this
from happening, dampen the soot deposits with a
wet brush or fine water spray before servicing the
heat exchanger.

AVERTISSEMENT

L’accumulation de suie sur un échangeur thermique
sale peut s’enflammer au contact d’une étincelle ou
d’une flamme et présenter un risque d’incendie ou
d’explosion. Afin d’empêcher que cela se produise,
humidifier les dépôts de suie à l’aide d’une brosse
mouillée ou par une pulvérisation fine d’eau avant
d’effectuer l’entretien de l’échangeur thermique.

The Mighty Stack has a premixed burner system.
These systems provide the burners with sufcient air

for complete combustion, and black carbon sooting is

seldom experienced. If sooting is suspected, view ports
for inspection of the heat exchanger are provided on
the side of the water heater. In the unlikely event that

there is a buildup of black carbon soot or other debris

on the heat exchanger, clean per the following:

1. Disconnect the electrical supply to the unit.

2. Turn off the gas supply by closing the manual gas

valve on the heater.

3. Disconnect and remove the wires, conduit and

Mighty Stack

sensors from all components that are attached to

the inlet/outlet header.

4. Isolate the heat exchanger from the water supply.

5. Disconnect the header anges from the inlet and
outlet.

6. Allow the heat exchanger to drain. Remove the

venting and remove the top, by removing the

screws that attach the top to the side panels.
Remove the side panels.

7. Remove the heat exchanger from the unit.
NOTE: Heat exchangers are heavy and may

require two people to remove to avoid personal

injury.

8. Clean the heat exchanger: A light accumulation

of soot or corrosion on the outside of the heat

exchanger can be easily removed. Use a wire

brush to remove loose soot and scale from the

heat exchanger.

9. NOTE: While the heat exchanger is out of the
unit, inspect the rewall refractory insulation.
Replace if necessary.

10. Inspect the inside of the copper tubes for scale
buildup. Scale can build up on the inner surface
of the heat exchanger tubes, which can restrict
water ow. If the tubes show signs of scaling,
clean the internal surface.

11. Reassemble in the reverse order, and check
appliance operation after start-up.

Page 25

NOTE: The warranty does not cover damage due to
lack of maintenance, lack of water flow, inadequate
water temperature, or improper operating practices
outlined in this manual.

Page 26

Laars Heating Systems

SECTION 8.
Trouble Shooting

8.1 Resolving Lockouts

There are many causes of lockouts. The three

most common causes are: (1) inadequate gas supply,

(2) poor combustion, (3) ignitor failure.

1. Inadequate gas supply: Before proceeding,

ensure that the gas supply has not been shutoff

or the LP tank (LP water heaters) is not empty.

Then, restart the water heater and observe the

operational cycle. After a 15-second fan pre­purge, the ignitor will heat up for 40 seconds,
and then the unit will light. If it does not, check

the gas supply pressure to the appliance, after
resetting the appliance and attempting another

start-up. The gas pressure to the appliance
must be above 5 in. w.c. (1.2 kPa) throughout
the entire start-up cycle. If it is not, correct the

supply problem (check gas valves or supply

piping). If the supply pressure is adequate,
consult the factory for assistance.

2. Poor Combustion: Poor combustion should
be suspected if there is a strong ue gas odor.

The odor may result from an improper gas/air
ratio (high or low O

appliances operate best with 45% excess air (8%

on natural gas, 9.2% CO2 on LP). Check the

CO

2

of the appliance and adjust if necessary.

CO

2

3. Ignitor failure: If the water heater goes through

a normal start cycle but combustion does not

occur, ignitor failure should be suspected. Check

the ignitor by unplugging the ignitor plug and

measuring the ignitor resistance. It should be
50-80 ohms. If the resistance is not 50-80 ohms,
replace the ignitor. If the resistance is correct,
reset the water heater and check for 120 VAC at
the ignitor plug during the start cycle. If there is

no voltage, replace the faulty ignitor wire harness

or the ignition control.

or CO2). Mighty Stack

2

8.2 Delayed Ignition — Possible Causes

A defective burner can cause a delayed ignition.

If the gas supply pressure is proper and the gas
valves are functioning properly, then burners should

be inspected. There should be no distortion or

perforations in the burners outside of the active burner

port area. Replace if indicated.

8.3 High Gas Consumption

Appliances operating with an improper air/

fuel ratio are very inefcient and consequently, have
very high gas consumption. Because efciency is

high when the CO
operating with low CO

appliances) consume more gas. Adjust the CO
for optimum efciency. If no combustion analyzing

equipment (CO
adjustment of the air/fuel ratio (CO

accomplished. The CO
natural gas and 9.2% at high re for LP. To check the

, rst verify that the supply gas pressure is within

CO

2

5 to 13 in. w.c. (1.2 to 3.2 kPa). With the Mighty Stack
running with all stages ring, set the air box pressure
to 1.8 in. w.c. (0.42 kPa) (as a starting point), by
adjusting the air shutter(s) at the intake of the fan(s).

Check the CO
adjustment to the CO

Size

199 17 1.6 14 1.0 11 0.7 10 0.5
300 26 3.5 20 2.3 17 1.6 15 1.2
399 34 6.3 27 4.0 23 2.8 19 2.1

Metric Equivalent

Size

199 64 0.5 51 0.3 43 0.2 37 0.2

300 97 1.1 77 0.7 64 0.5 55 0.4

399 129 1.9 103 1.2 86 0.9 74 0.6

Notes: gpm = gallons per minute, lpm = liters per minute,
H/L = head loss, ft = head loss in feet,
m = head loss in meters.
Maximum temperature rise is 35°F (19°C), as shown.
Head loss is for water heater’s heat exchanger only.
N/R = not recommended.

For troubleshooting purposes, Table 8 gives preferred
flow rates between the tank and heater. The heater is
designed for between 20° and 30°F temperature rise.

20°F 25°F 30°F 35°F

flow
gpm

11°C 14°C 17°C 19°C

ow

lpm

Table 8. Water Flow Requirements.

is high (or O2 is low), appliances

2

or high O2 (especially LP

2

or O2) is available then a proper

2

should be 8% at high re for

2

, and adjust the air shutters if further

2

H/L
feet

H/L mow

is needed.

2

flow

H/L

gpm

feet

H/L mow

lpm

or O2) cannot be

2

flow

H/L

gpm

feet

H/L mow

lpm

or O2

2

flow
gpm

lpm

H/L

feet

H/L

m

Mighty Stack

Page 27

SECTION 9.
Replacement Parts

Only genuine Laars replacement parts should be used.

9.1 General Information

To order or purchase parts for the Laars Mighty Stack, contact your nearest Laars dealer or distributor. If they
cannot supply you with what you need, contact Customer Service (see back cover for address, telephone and fax
numbers).

9.2 Parts List

Item Description Size 199 Size 300 Size 399

COMBUSTION CHAMBER COMPONENTS SeeFigure9

1 Assembly, Base 2C1000 3C1000 4C1000
2 Support, Tile Notch 2C2109 3C2019 4C2109
3 Chamber, Refractory, Heat Exchanger T2108802 T2108803 T2108804
4 Assembly, Front Panel, Combustion Chamber 2C2023 3C2023 4C2023
5 Panel, Rear, Combustion Chamber 2C2006 3C2006 4C2006
6 Panel, Top, Combustion Chamber 2C2001 3C2001 4C2001
7 Chamber, Right Side, Bottom 2C2201 2C2201 2C2201
8 Chamber, Left Side, Bottom 2C2601 2C2601 2C2601

9 Chamber, Side, Top 2C2002 2C2002 2C2002
10 Panel, Right Side, Air Box 2C2016 2C2016 2C2016
11 Panel, Left Side, Air Box 2C2015 2C2015 2C2015
12 Weldment, Duct, Blower 2C2500 2C2500 2C2500
13 Panel, Top, Air Box 2C2008 3C2008 4C2008
14 Plate, Spacer, Burner/Manifold 2C2017 3C2017 4C2017
15 Panel, Front, Air Box 2C2009 3C2009 4C2009
16 Assembly, Exhaust Vent, 5" Dia. 2C2100 3C2100 4C2100
17 Weldment, Flue 2C2300 2C2300 2C2300
18 Assembly, Air Shutter, Blower 2C5000 2C5000 2C5000
20 Assembly, Filter Housing 40L3900 40L3900 40L3900

Assembly, Removeable Filter 40L3800 40L3800 40L3800

Media, Filter R2073200 R2073200 R2073200
21 Hose, Duct, Flexible, 4" Dia. x 16.50" P0101402 P0101403 P0101404
22 Blower/Motor E0254000 E0254000 E0254000
23 Gasket, Blower (Fasco) S2104400 S2104400 S2104400
25 Assembly, Sight Glass 10956000 10956000 10956000
26 Ignitor, Hot Surface RW2002300 RW2002300 RW2002300
27 Gasket, Burner S2104300 S2104300 S2104300
28 Burner, Main, (Pressure Port) L0063301 L0063301 L0063301
29 Burner, Main L0063300 L0063300 L0063300
30 Gasket, Blower Duct S2104500 S2104500 S2104500
31 Kit, Insulation, Combustion Chamber T2015808 T2015809 T2015810
32 Gasket, Flue Housing S2104600 S2104600 S2104600
33 Assembly, Heat Exchanger, Copper 20L4230 30L4230 40L4230

Page 28

Item Description Size 199 Size 300 Size 399

JACKET COMPONENTS SeeFigure10

1 Assembly, Base/Support 20L1000 30L1000 40L1000
2 Weldment, Base, Upper Level 20L1200 30L1200 40L1200
3 Support, Corner (4 req'd) 40L2001 40L2001 40L2001
4 Support, Corner 40L2002 40L2002 40L2002
5 Support, Corner 40L2003 40L2003 40L2003
6 Air Inlet, Weldment 20L2510 20L2510 40L2520
7 Panel, Top/Bottom (2 req'd) 20L3002 30L3002 40L3002
8 Panel, Top/Bottom (2 req'd) 40L3003 40L3003 40L3003

9 Panel, Jacket 20L3007 30L3007 40L3007
10 Panel, Jacket 40L3008 40L3008 40L3008
11 Panel, Jacket 40L3009 40L3009 40L3009
12 Panel, Jacket 40L3010 40L3010 40L3010
13 Panel, Jacket 40L3011 40L3011 40L3011
14 Panel, Top 20L3013 30L3013 40L3013
15 Rear Panel 20L3015 30L3015 40L3015
16 Assembly, Front Panel, Jacket 20L3100 30L3100 40L3100
17 Assembly, Front Panel, Jacket 20L3101 30L3101 40L3101
18 Panel, Cover, Filter Inlet (2 req'd) 40L3701 40L3701 40L3701
19 Latch, Door, Assembly (18 req'd) 20087300 20087300 20087300

HEAT EXCHANGER COMPONENTS SeeFigure11

1 Assembly, Tube, Heat Exchanger, Copper R2C4100 R3C4100 R4C4100

Assembly, Tube, Heat Exchanger, Cupro-Nickel R2C4120 R3C4120 R4C4120

2 Header, Inlet/Outlet 2F4122 2F4122 2F4122

Laars Heating Systems

3 Header, Return 2C4103 2C4103 2C4103

4 Chamber, Header, Heat Exchanger (2 req'd) 2C4001 2C4001 2C4001

5 Bafe, End, Heat Exchanger Tube (2 req'd) 2C4002 2C4002 2C4002

6 Flange, Connection, 1-1/2" NPT (2 req'd) S0076401 S0076401 S0076401

7 Gasket, Flange, 1-1/2" (2 req'd) S0076500 S0076500 S0076500

8 Valve, Press. Relief, 3/4" NPT X 3/4" Npt, 125

psi

9 Well, Immersion, Hi-Limit Temperature E0234201 E0234201 E0234201

Well, Immersion, 1/2" NPT w/Probe E2058300 E2058300 E2058300

10 Gasket, 5/8" Tube, 7/32" Thick (20 req'd) S0070800 S0070800 S0070800

GAS TRAIN COMPONENTS SeeFigure12

1 Weldment, Gas Manifold, Main L0063702 L0063703 L0063704

2 Manifold, Gas, On/Off L0063414 L0063416 L0063418

3 Orice, LP Gas, 1.35 mm (0.053" dia.) L0063000 L0063000 L0063000

Orice, Nat. Gas, 2.30 mm (0.091" dia.) L0062900 L0062900 L0062900

5 Gas Valve, Combination, LP, (D.S.I.), 3/4" NPT

3/4" NPT
Gas Valve, Combination, Nat., (D.S.I.), 3/4" NPT

x 3/4" NPT
6 Cover, Gas Inlet, Air Box 2C2018 2C2018 2C2018
7 Manual Gas Valve

A0001200 A0001200 A0001200

V0079500 V0079500 V0079500

V0079400 V0079400 V0079400

Mighty Stack

Item Description Size 199 Size 300 Size 399

CONTROL PANEL COMPONENTS SeeFigure13

1 Switch, Pressure, Diaphragm, SPST E0255500 E0255500 E0255500
2 Switch, Pressure, Diaphragm, SPDT E0240900 E0240900 E0240900
3 Switch, Limit, High Temperature, Volume Water E2324200 E2324200 E2324200
4 Transformer, 24, 120V, 50VAC E0180500 E0180500 E0180500
5 Ignition Control, Hot Service Ignition E0253400 E0253400 E0253400
6 SPDT Toggle Switch E0109200 E0109200 E0109200
7 Tray, Control Panel 20L7002 30L7002 40L7002
8 Relay, Time Delay, 24 Vac, Delay On Break,

Adjustable

9 Ignition Control, HSI, Fenwal E0253400 E0253400 E0253400

Switch, Rocker, 10A, 250 VAC 1/2 HP, 15A, 125
VAC 1/2 Hp

Switch, Temperature, Manual Reset, 250°,

SPST, Trip-Free
10 DPDT Toggle Switch, 15 Amps, 3/4 HP E2056300 E2056300 E2056300
11 Block, Terminal, Double Row, 16-Position E2327500 E2327500 E2327500
12 Jumper, Terminal Block E0102000 E0102000 E0102000
13 Label, Terminal, Control Contacts H2339100 H2339100 H2339100
14 Harness, Main E2337800 E2337800 E2337800
15 Harness, Wire, On/Off, Switch E2337900 E2337900 E2337900

PUMP ASSEMBLY COMPONENTS SeeFigure14

1 Circulator Pump Assembly A2112200 A2112200 A2112200

Alternate Soft Water Pump A2112212 A2112212 A2112212

2 Union, 1-1/4" C x C 36-518 36-518 –

Union, 1-1/2" Solder Joint, Copper/Brass Nut – – P2020100

3 Adapter, Copper, C x M, 1-1/4" x 1-1/2" NPT P2049500 P2049500 –

Adapter, 1-1/2" Male NPT x 1-1/2" soc, Copper – – P2019700

4 Water Flow Switch, Outdoor E0013000 E0013000 E0013000
5 Tee, 1-1/4" soc x 1" sox x 1-1/4" soc, Copper P2079700 P2079700 –

Tee, 1-1/2" soc x 1" soc x 1-1/2" spc – – P2079600

6 Adapter, Copper, 1-1/4" to 1" NPT P2079800 P2079800 P2079800
7 Flow Switch Paddle E2105400 E2105400 E2105400
8 Elbow, 1-1/2" NPT x 1-1/2" CU, Cast Brass – – P2079300

E2077700 E2077700 E2077700

E2322700 E2322700 E2322700

E2103200 – –

(6)

Page 29

Page 30

Laars Heating Systems

Figure 9. Combustion Chamber Components.

Mighty Stack

Page 31

Figure 10. Jacket Components.

Page 32

Laars Heating Systems

Figure 11. Heat Exchanger Components.

Mighty Stack

Page 33

Figure 12. Gas Train Components.

Page 34

Laars Heating Systems

Figure 13. Control Panel Components.

Mighty Stack

Page 35

Figure 14. Pump Assembly Components.

Dimensions and specifications subject to change without notice in accordance with our policy of continuous product improvement.

®

800.900.9276 • Fax [phone] (CustomerService,ServiceAdvisors)

20 Industrial Way, Rochester, NH 03867 • 603.335.6300 • Fax [phone]

1869 Sismet Road, Mississauga, Ontario, Canada L4W 1W8 • 905.238.0100 • Fax [phone]

www.Laars.comLitho in U.S.A. © Laars Heating Systems 1110 Document 2155

H2350400-