LAARS EBP 175 User Manual
Installation, Operation and Maintenance Instructions Document 1187E
Installation,
Operation and
Maintenance Instructions for
ENDURANCE
Model EBP
110 & 175 MBTU/h
Modulating Combination Boiler
(natural or propane gas)
WARNING
FOR YOUR SAFETY: This product must be installed and serviced by a professional service
technician, qualied in hot water boiler 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. 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 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 qualied 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 inammables 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
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 qualié ou
par le fournisseur de gaz.
AVERTISSEMENT
H2313500E
Page 2
LAARS Heating Systems
TABLE OF CONTENTS
SECTION 1.
General Information
1.1 Introduction ....................................................3
1.2 Codes and Standards ....................................3
1.3 Unpacking the Appliance ...............................3
1.4 Locating the Appliance ..................................4
1.5 Clearances ....................................................4
SECTION 2.
Venting Options
2.1 Concentric Direct Vent ...................................5
2.1.1 Concentric Vent Description .......................... 5
2.1.2 Laars Concentric Vent Kits ............................ 5
2.1.3 Horizontal Concentric Vent Location .............5
2.2 Stainless Steel Single Pipe Horizontal
and Vertical Vents — Category IV ................. 9
2.3 Air Source For Combustion (when not
ducted to the Endurance) ............................11
2.3.1 Air From Inside the Building ........................11
2.3.2 All Air From Outdoors .................................. 11
2.3.3 Connecting Special Gas Vent to the
Appliance ..................................................... 12
2.4 Non-Concentric Combustion Air .................. 12
SECTION 3.
Gas Piping
3.1 Gas Piping ................................................... 12
3.2 Domestic Water Piping ............................... 13
3.3 Anti-Freeze — Domestic Water ...................14
SECTION 4.
Hydronic Heat Piping
4.1 Hydronic Piping ...........................................14
4.2 Using in a Combined Hot Water Heating
and Chilled Water Cooling System .............. 17
4.3 Water Quality and Treatment .......................17
4.4 Anti-Freeze .................................................. 17
4.4.1 Endurance Boiler Low
Temperature Feature ...................................17
4.4.2 Anti-Freeze Boiler Additives ........................17
SECTION 5.
Electrical Connections
5.1 Electrical Connections ................................. 20
SECTION 6.
Using the Boiler Control
6.1 Front Panel Display .....................................22
6.2 Control Logic ...............................................22
6.3 View Menu ...................................................22
6.4 Setpoint Menu .............................................23
6.4.1 “SP” Supply Temperature ............................23
6.4.2 “PO” Pump Operation ..................................23
6.4.3 “Pd” Pump Delay .........................................23
6.4.4 “Oar” Outdoor Reset ....................................24
6.4.5 “Oal” Minimum Outdoor Reset Point ...........24
6.4.6 “rc” Outdoor Reset Ratio .............................24
6.4.7 “oTo” Warm Outdoor Shutdown ................... 24
6.4.8 “unl” Temperature Units ...............................24
6.4.9 “Dif” Burner On Differential .......................... 24
6.5 Calculated Control Values ...........................25
6.5.1 ACV Release .............................................. 25
6.5.2 Tank Charge Setting ....................................25
6.5.3 Burner On Point ...........................................25
6.5.4 Modulation Point ..........................................25
6.6 Other Control Functions ..............................25
6.6.1 Using Buttons on Control .............................25
6.6.2 Alarm Acknowledge .....................................25
6.6.3 Power On/Off ...............................................25
6.6.4 Low Fire Hold ..............................................25
6.6.5 High Fire Hold ..............................................25
6.6.6 Pump Operation ..........................................25
6.6.7 Anti-Condense Valve Operation ..................25
6.6.8 Field-Supplied Outdoor Reset Controls .......26
SECTION 7.
Boiler Start Up
7.1 Removal of Boiler From Common Vent .......26
7.2 Filling the System ........................................28
7.3 Firing Burner ................................................28
SECTION 8.
Maintenance and Component Description
8.1 Unit Pump ....................................................29
8.2 Gas Valve ....................................................29
8.3 Safety Limit Switch ......................................29
8.4 Boiler Control ...............................................29
8.5 Ignition Control ............................................29
8.6 Ignitor / Flame Sensor Assembly .................29
8.7 Transformer ................................................. 30
8.8 PMW Board .................................................30
8.9 Blower ..........................................................30
8.10 Transfer Tank .............................................. 30
8.11 Cleaning the Boiler Coil ............................... 30
SECTION 9.
Servicing
9.1 Sequence of Operation ................................31
9.2.1 Fault Code Identication ..............................31
9.2.2 Fault Correction ........................................... 31
9.2.3 Resolving Lockouts (LO) .............................33
SECTION 10.
Air Orice and Gas Valve Adjustment
.....................................................................34
SECTION 11.
Symptom Evaluations
11.1 Delayed Ignition ...........................................35
11.2 Short Cycling ...............................................35
11.3 Noisy Operation ...........................................35
11.4 Insufcient Hot Water ..................................36
11.5 High Gas Consumption ...............................36
SECTION 12.
Parts Identication
.....................................................................38
Endurance
Page 3
SECTION 1.
General Information
1.1 Introduction
The EBP Endurance is a low pressure, direct
vent, hot water boiler that provides priority domestic
hot water on demand as well as hydronic space
heating. The unit has a twenty gallon tank which holds
boiler water (as opposed to domestic water storage).
The boiler water is kept hot at all times to
provide immediate response to call for heat or
domestic water. Domestic water is heated by the boiler
water through a stainless steel plate heat exchanger.
This appliance has a circulating pump and a
bypass loop, and provides circulation for the heating
system and adequate ow for its own needs.
It may be necessary to install a system circulator to
achieve the required ow rate through the system.
This appliance also features a forced draft,
premixed combustion system. All air for combustion
is supplied with the gas to the burner (ame holder).
Both the intake air and the gas are metered through
separate orices before entering the combustion air
blower. The blower forces the air/fuel mixture through
the ame holder and into the combustion chamber.
The mixture is ignited from the hot surface ignitor and
burns. Hot gases are forced out between the passes of
the heat exchanger into the ue collector. Flue gases
are discharged into the outside atmosphere through the
vent terminal.
The appliance can operate with a concentric vent
system that will provide outside air for combustion.
Other venting arrangements can be provided for the
appliance to include an alternative 50 equivalent feet
maximum horizontal or condensate trapped vertical
vent.
1.2 Codes and Standards
The Endurance may be a direct vent or Category
IV Boiler. All installations must be made in accordance
with:
a. The National Fuel Gas Code, ANSI Z223.1/
NFPA 54 latest edition, or
b. CSA B149.1 Natural Gas and Propane
Installation Code.
c. The requirements of the local utility or other
authorities having jurisdiction take precedence
over the general instructions contained herein.
All electrical wiring is to be done in accordance with:.
a. The National Electrical Code (NFPA 70), latest
edition or
b. The Canadian Electrical Code (CSA C22.1),
latest edition.
c. All applicable local installation codes must also
be adhered to.
All vent installations must be made in accordance with:
a. The applicable venting requirements of the
National Fuel Gas Code (ANSI Z223.1/NFPA
54), latest edition; or
b. in Canada, The Natural Gas and Propane
Installation Code (CSA B149.1), latest edition.
All applicable provisions of local building codes
should also be adhered to.
Figure 1. Combo Heating/Domestic Water
1.3 Unpacking the Appliance
Remove all packing and tie down materials.
Make immediate claims (to the carrier) if the appliance
and its packaging are damaged.
Page 4
1 2 3 4 5 6 7 8 9 10 11 12 13 14
E B P I F 2 X
LAARS Heating Systems
Prod. Line
E = Endurance
Usage
B = Combination,
Heating &
Domestic
Water
Type
P = Standard
Figure 3. Model Structure.
BTU Input
0 1 1 0
0 1 7 5
1.4 Locating the Appliance
The appliance is designed for installation on
combustible ooring, in alcoves, basements, closets,
or utility rooms. It must NOT be installed on
carpeting. IF INSTALLED IN A FINISHED AREA,
PROVISION SHOULD BE MADE FOR DRAINAGE
OF ANY ACCIDENTAL SPILLAGE OR LEAKAGE.
The location for the unit should be chosen with
regard to venting dimensions, convenient access to
piping, and accessibility for service and cleaning.
The boiler shall be installed so that the gas
ignition system components are protected from water
(dripping, spraying, rain, etc.) during appliance
operation or service (circulator replacement, control
replacement, etc.).
Fuel
N = Natural Gas
P = Propane
A = 0' - 5,000'
H = Over 5,000'
Back 1 inch 25mm
Left Side 1 inch 25mm
Right Side 1 inch 25mm
Front 1 inch 25mm
Top (Alcove Install) 1 inch 25mm
Top (Closet Install)* 22 inches 559mm
Vent: Concentric, Direct 0 inch 0mm
Vent: Category 3 inches 76mm
Front 18 inches 457mm
Left Side 6 inches 152mm
Right Side 6 inches 152mm
*Minimum closet height 6'9" 206 cm
Location
I = Indoor
Altitude
Minimum Clearances From Combustible Materials
Suggested Serviceability Clearances
Firing Mode
F = Modulating
Table 1. Clearances.
Revision
2 = Second
Revision
Country of Sale
A = USA & Canada
R = Russia
Options Code
X = None
1.5 Clearances
The dimension and criteria in Table 1 should be
followed when choosing the location for the unit.
SECTION 2.
Venting Options
The Endurance boilers are certied as direct vent,
sealed combustion boilers, when vented using one of
the following two methods:
1) Concentric direct vent, which has a ue gas pipe
inside a combustion air pipe.
2) Non-concentric direct vent, using separate pipes
for the ue gases and the combustion air.
The Endurance boilers can also take air from the
space (when properly sized), and be vented as a
Category IV appliance.
The following sections describe the requirements
for each of these methods.
IMPORTANT NOTE REGARDING ENDURANCE
VENTING: Regardless of the venting arrangement
being used, the ue gas vent material used with
the Endurance MUST be stainless steel special
gas vent listed to U.L. Standard 1738 and U.L.C.
Standard 636. Endurance ue gases must never
be vented into a masonry chimney or vented
with B-vent or other galvanized vent material.
Endurance units are not permitted to be common
vented with any other appliance(s), including
other Endurance appliances.
Endurance
Page 5
2.1 Concentric Direct Vent
2.1.1 Concentric Vent Description
Endurance concentric direct vent is a sealed-
combustion system. It can be used for vent systems
with a maximum of 15 linear feet (4.6m) and three
elbows. All of the air is drawn in from the outside
through a 5" stainless steel outer pipe. Flue gases
are vented through a 3" stainless steel pipe that is
positioned inside the 5" intake pipe. Hot ue gases
are surrounded by the intake ow of cooler outdoor
air (see Figure 4). Laars offers two concentric vent
kits, described in section 2.1.2. Laars concentric vents
may be installed through, and be in contact with,
combustible materials.
2.1.2 Laars Concentric Vent Kits
The Endurance is certied with a maximum of
15 linear feet (4.6m) of concentric piping and three
sets of elbows. There are two concentric vent kits
offered by Laars. Both kits, and all Laars Endurance
vent material meet the requirements of U.L. Standard
1738 and U.L.C. Standard 636. The horizontal vent kit
is part number 2400-009. The vertical vent kit is part
number 2400-011. See Figures 5 and 6, which show
the components included with the kits and venting
congurations. Installation instructions are included
with the kits. Rules for concentric venting, vent
material and vent terminal placement are discussed in
Figure 4. Combustion Air and Flue Gas Paths.
the rest of Section 2 of this manual.
For additional length, and/or ttings, to extend
the kits to maximum 15 linear feet (4.6m) and three
elbows, individual components are available. These
components are shown in Figure 7.
2.1.3 Horizontal Concentric Vent Location
The centerline of the vent opening must be at
least 16-1/2" (42cm) above grade, outside. Should it
be impossible to locate the opening centerline 16-1/2"
(42cm) above grade, use optional concentric vent
terminal extension (part number 2400-428), shown in
Figure 7.
In the U.S., vent terminals must be at least 3 feet
(0.9m) above any forced air inlet located within 10
feet (3.0m). In Canada, vent terminals must be at least
6 feet (1.8m) from any forced air inlet.
In the U.S., a direct vent terminal must be at
least 12" (30cm) from any window or door that may
be opened, or any other nonmechanical opening.
For an Endurance that is not direct vented (vented as
Category IV), the vent terminal must be at least 4 feet
(1.2m) below or to the side of, and 12" (30cm) above
any such opening.
In Canada, a direct vent or non-direct vent
terminal must be at least 36" (91cm) from any window
or door that may be opened, or any other non-
mechanical opening.
The vent opening should be well away from
shrubbery or other obstructions that would prevent free
air ow to and from the vent terminal.
If the vent terminal location chosen is less than
18" (46cm) below an overhang, the 3" vent pipe
must extend to the outside edge of the overhang,
to prevent the accumulation of ue gas (see Figure
9). Accumulating ue gas can contaminate the
combustion air, causing nuisance lockouts of the
ignition system. In addition, accumulation of ue
gases can settle on, and damage the structure’s
surfaces.
Vent terminals must not terminate in a location
where condensate or vapor may be a nuisance, hazard,
or could be a detriment to other equipment. See Figure
8 for more detail concerning vent terminal placement
in the U.S. and Canada.
Do not locate the vent terminal where blockage
by snow is a possibility, or where ue products
could strike against building materials and cause
degradation.
When multiple Endurance units are used,
the concentric vent terminals may be side-by-side,
provided that they are at least 18" (46cm) apart,
centerline to centerline (see Figure 10).
A horizontal vent system must pitch downward,
toward the terminal and away from the Endurance,
as shown in Figure 11. It must pitch at least 1/4"
per foot (21mm per meter). Be sure to take this
into consideration when choosing the vent terminal
location.
The vertical vent terminal must be placed such
that the bottom of the vent cap is at least 2-feet (0.6m)
above any structure (such as the peak of a roof or
adjacent wall) within 10 feet (3.0m), and must be at
Page 6
LAARS Heating Systems
Conguration 1:
Maximum horizontal = 28"
Maximum vertical = 26"
(Measurements are from the centerlineof the venting to
the boiler top or face of outside wall.)
Dimensions shown in inches.
Figure 5. Horizontal Vent Kit 2400-009.
Conguration 2:
Maximum horizontal = 38"
Maximum vertical = 16"
(Measurements are from the centerline of the venting to
the boiler top or face of outside wall.)
Dimensions shown in inches.
Figure 6. Vertical Vent Kit 2400-011.
Endurance
Page 7
Figure 7. Concentric Vent Parts.
Dimensions shown in inches.
Page 8
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 soft 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 soft 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 nonmechanical 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 CAN/CGA-B149 Installation Codes.
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 specied 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 specied in CAN/CGA-B149, clearance is in accordance with local installation codes and the requirements of the gas
supplier.
Figure 8. Vent Terminal Clearance.
Endurance
Figure 9. Clearance from Overhang.
Page 9
Figure 12. Vertical Vent Terminal Placement.
Figure 10. Multiple Concentric Vent Clearances.
Figure 11. Vent System Pitch.
least 3 feet (0.9m) above where the vent pipe exits the
roof (see Figure 12).
When vertical vent systems have horizontal
components, they must have a condensate drip tee
in the offset. All horizontal portions of the vent
system must slope a minimum 1/4" per foot toward
the condensate drip tee. Laars vertical vent kit and
individual venting components have condensate tees
that work in a vertical vent system, and therefore it
is not necessary to have an offset in a vertical vent
system that uses these parts.
2.2 Stainless Steel Single Pipe Horizontal
and Vertical Vents – Category IV
Stainless steel special gas vent listed to U.L.
Standard 1738 and U.L.C. Standard 636 must be used
to vent all models. Three-inch or 4-inch material can
be used. Vent pipe and ttings are manufactured to
these standards by HeatFab, Inc. under the trade name
of Saf-T Vent®, by Z-Flex™ under the trade name of
Z-Vent®, and by ProTech Systems, Inc. under the
trade name FasNSeal®. Follow the special gas vent
manufacturer’s instructions regarding design, location
and assembly of the vent system.
The appliance may be vented with any number
of elbows or ttings, providing that the maximum
equivalent feet of venting is not exceeded. Equivalent
feet of vent material is shown in Table 2, along with
information about vent temperature and pressure.
Elbows (90°) in the vent system shall be considered to
be 5 equivalent feet (1.5m).
A horizontal vent system must pitch downward,
toward the terminal and away from the Endurance,
as shown in Figure 11. It must pitch at least 1/4"
per foot (21mm per meter). Be sure to take this
into consideration when choosing the vent terminal
location.
For applications requiring vertical venting
through a roof, the same limitations for length and
ttings apply (see Table 2). Vertical vents greater than
7 feet (2.1m) in length must use a condensate trap.
When vertical vent systems have horizontal
components, they must have a condensate drip tee
Page 10
LAARS Heating Systems
Figure 13. 3" Vent Parts.
Dimensions shown in inches.
Endurance
Page 11
Minimum clearance from
combustibles (vent) U.S.* 3" 8cm
Minimum clearance from
combustibles (vent) Canada 6" 15cm
Max. ue gas temp. 325°F 163°C
Max vent pressure 1.5" w.c. 0.4kPa
Max. equivalent ft. of 3" venting (any 50 15
combination of horizontal or vertical) equiv. feet equiv. meters
Max. equivalent ft. of 4" venting (any 100 30
combination of horizontal or vertical) equiv. feet equiv. meters
*Note: To use 3" (8cm) clearance, the vent must be open on at least
one side. If fully enclosed, clearance is 6" (15cm)
Table 2. Category IV Vent Parameters.
in the offset. All horizontal portions of the vent
system must slope a minimum 1/4" per foot toward
the condensate drip tee. Laars vertical vent kit and
individual venting components have condensate tees
that work in a vertical vent system, and therefore it
is not necessary to have an offset in a vertical vent
systems that use these parts.
The vertical vent terminal must be placed such
that the bottom of the vent cap is at least 2-feet (0.6m)
above any structure (such as the peak of a roof or
adjacent wall) within 10 feet (3.0m), and must be at
least 3 feet (0.9m) above where the vent pipe exits the
roof (see Figure 12).
Laars offers 3" vent parts for non-concentric
venting, including an in-line condensate tee and vent
caps for vertical venting. See Figure 13 for 3" vent
parts, and Figure 15 for an example of the inline
condensate in a vertical vent system.
IMPORTANT NOTE REGARDING ENDURANCE
VENTING: Regardless of the venting arrangement
being used, the ue gas vent material used with
the Endurance MUST be stainless steel special
gas vent listed to U.L. Standard 1738 and U.L.C.
Standard 636. Endurance ue gases must never
be vented into a masonry chimney or vented with
B-vent or other galvanized vent material. Endurance
units are not permitted to be common vented with
any other appliance(s), including other Endurance
appliances.
2.3 Air Source For Combustion
(when not ducted to the Endurance)
When using Category IV venting methods the
appliance draws all combustion air through its top and
from the adjacent space. When locating the appliance
in unconned spaces in buildings, inltration may be
adequate to provide air for combustion and ventilation.
However, in buildings of unusually tight construction,
or when locating the appliance in a conned space,
additional air should be provided and the guidelines
below must be followed:
2.3.1 Air From Inside the Building
The following method shall be used to size the
air openings for boilers that are getting all of their
combustion air from inside the building.
The conned space shall be provided with two
permanent openings communicating directly with
other spaces of sufcient volume so that the combined
volume of all such spaces meets the criteria for an
unconned space. The total input of all gas utilization
equipment installed in the combined spaces shall be
used to determine the required minimum volume.
Each opening shall have a minimum free area of not
less than 1 in.2/1000 Btu/hr (220 mm2/kW) of the total
input rating of all gas utilization equipment in the
conned space, but not less than 100 in.2 (645 cm2).
One opening shall commence within 12 in. (30 cm) of
the top, and one opening shall commence within 12 in.
(30cm) of the bottom, of the enclosure. The minimum
dimension of air openings shall be not less than 3 in.
(8 cm).
2.3.2 All Air From Outdoors
When all air is provided from outdoors, but
not ducted directly to the Endurance, the following
methods shall be used to size the air opening(s).
a. Tw o permanent openings, one commencing
within 12 in. (30 cm) of the top and one
commencing within 12 in. (30 cm) of the bottom,
of the enclosure shall be provided. The openings
shall communicate directly, or by ducts, with
the outdoors or spaces (crawl or attic) that freely
communicate with the outdoors.
a1. Where directly communicating with the
outdoors or where communicating to the
outdoors through vertical ducts, each
opening shall have a minimum free area
of 1 in.2/4000 Btu/hr (550 mm2/kW) of
total input rating of all equipment in the
enclosure.
a2. Where communicating with the outdoors
through horizontal ducts, each opening
shall have a minimum free area of not less
than 1 in.2/2000 Btu/hr (1100 mm2/kW) of
total input rating of all equipment in the
enclosure.
b. One permanent opening, commencing within 12
in. (30 cm) of the top of the enclosure, shall be
permitted where the equipment has clearances
of at least 1 in. (2.5 cm) from the sides and back
and 6 in. (16 cm) from the front of the appliance.
The opening shall directly communicate with the
outdoors or shall communicate through a vertical
or horizontal duct to the outdoors or spaces that
freely communicate with the outdoors and shall
have a minimum free area of:
Page 12
termination
LAARS Heating Systems
b1. 1 in.2/3000 Btu/hr (700 mm2/kW) of
total input rating of all equipment in the
enclosure, and
b2. Not less than the sum of the areas of all
vent connectors in the conned space.
2.3.3 Connecting Special Gas Vent to
the Appliance
When drawing combustion air from the adjacent
space, part number 2400-415 (room adapter with
screen) can be used. One portion of this assembly
connects to the 5" air collar (with a screen for the
combustion air) and the other part connects to the 3"
ue opening (see Figure 14). The rest of the 3" vent
system can be connected to the adapter within the
2400-415.
2.4 Non-Concentric Combustion Air
An alternate, non-concentric combustion air
source may be installed (as shown in Figure 15),
2400-435 tee
(to separate
venting from
combustion
air)
Combustion
Chamber
Fan
2400-416
concentric rain cap
(use only on systems
with condensate trap)
2400-435 tee
(to separate
venting from
combustion air)
3" diameter vent
(50 equivalent feet, maximum)
4" combustion air pipe
(15 equivalent feet, maximum)
Non-Concentric Direct Vent with
Horizontal Vent.
2400-370
vertical vent cap
(can be used on system with
or without condensate trap)
2400-409 condensate trap
(used if vent height is
greater than7feet)
4" combustion air pipe
2400-426
3" vent
with screen
combustion
4" air terminal
(field-supplied)
combustion
air
vent
gases
air
Figure 14. Combustion Air from Room.
provided that the minimum 4" diameter combustion air
duct does not exceed 15' (4.6m). Termination should
include an air screen and be located in a qualied air
space (see Section 2.3) or outside.
Separated combustion air / ue gas may be
considered either “mechanical draft” or “direct vent”.
To be considered “direct vent”, all of the combustion
air and ue gas piping must be sealed stainless steel
special gas vent, listed to U.L. 1738 and U.L.C. 636.
When the system meets this requirement, vent terminal
clearances may be less than that of a non-direct
vent system. See Figure 8 for direct vent terminal
clearances.
4" air terminal
(field-supplied)
Combustion
Chamber
Fan
Figure 15. Non-Concentric Combustion Air.
Non-Concentric Direct Vent with
Vertical Vent.
The combustion air pipe may be galvanized
material, but if used, the system is a “mechanical vent”
system, and the vent terminal clearances must be per
the rules for “mechanical vent” systems (see Figure 8).
SECTION 3.
3.1 Gas Piping
The appliance requires an inlet gas pressure of
at least 4" w.c. (1.0kPa) and no greater than 13" WC
(3.2kPa). Check with your local gas utility or supplier
for availability of this pressure range.
Refer to Table 3 to size the supply piping to
minimize pressure drop between meter or regulator
and unit.
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