LAARS EBP 175 User Manual

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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, qualified in hot water boiler 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. 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.

H2313500E

AVERTISSEMENT

Assurez-vous de bien suivres les instructions données dans cette notice pour réduire au minimum le risque d’incendie ou d’explosion ou pour éviter tout dommage matériel, toute blessure ou la mort.

Ne pas entreposer ni utiliser d’essence ni d’autres vapeurs ou liquides 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 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.

	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

2.2Stainless Steel Single Pipe Horizontal

and Vertical Vents — Category IV..................

2.3Air 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

2.3.3Connecting 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

4.2Using in a Combined Hot Water Heating

	and Chilled Water Cooling System...............	17
4.3	Water Quality and Treatment.......................	17
4.4	Anti-Freeze...................................................	17

4.4.1Endurance 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 Identification..............................	31
9.2.2	Fault Correction............................................	31
9.2.3	Resolving Lockouts (LO)..............................	33
SECTION 10.
Air Orifice 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	Insufficient Hot Water...................................	36
11.5	High Gas Consumption................................	36
SECTION 12.
Parts Identification
	.....................................................................	38

Endurance	Page 3

SECTION 1.

General Information

1.1Introduction

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 flow for its own needs.

It may be necessary to install a system circulator to achieve the required flow 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 (flame holder).

Both the intake air and the gas are metered through separate orifices before entering the combustion air blower. The blower forces the air/fuel mixture through

the flame 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 flue 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.

1.2Codes 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.

1.3Unpacking the Appliance

Remove all packing and tie down materials.

Make immediate claims (to the carrier) if the appliance and its packaging are damaged.

Figure 1. Combo Heating/Domestic Water

Page 4	LAARS Heating Systems

Prod.

Line

BTU

Input

Fuel

Location

Revision

Options

Code

E = Endurance

0 1 1 0

N =Natural Gas

I = Indoor

2 = Second

X =None

0 1 7 5

P = Propane

Revision

Usage

B =Combination,

Altitude

Firing Mode

Country of Sale

Heating &

A = 0' - 5,000'

F = Modulating

A = USA & Canada

Domestic

H =Over 5,000'

R =Russia

Water

Type

P =Standard

Figure 3. Model Structure.

1.4Locating the Appliance

The appliance is designed for installation on

combustible flooring, 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 ANYACCIDENTAL 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.).

1.5Clearances

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 certified as direct vent, sealed combustion boilers, when vented using one of the following two methods:

1)Concentric direct vent, which has a flue gas pipe inside a combustion air pipe.

2)Non-concentric direct vent, using separate pipes for the flue gases and the combustion air.

Minimum Clearances From Combustible Materials

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
Suggested Serviceability Clearances
Front	18 inches 457mm
Left Side	6 inches 152mm
Right Side	6 inches 152mm

*Minimum closet height 6'9" 206 cm

Table 1. Clearances.

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 flue 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 flue 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 sealedcombustion 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 flue gases are surrounded by the intake flow 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 certified 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 configurations. 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 fittings, 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 nonmechanical opening.

The vent opening should be well away from shrubbery or other obstructions that would prevent free air flow 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 flue gas (see Figure 9). Accumulating flue gas can contaminate the combustion air, causing nuisance lockouts of the ignition system. In addition, accumulation of flue 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 flue 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

Configuration 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.

Configuration 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 5. Horizontal Vent Kit 2400-009.

Figure 6. Vertical Vent Kit 2400-011.

Endurance

Page 7

Dimensions shown in inches.

Figure 7. Concentric Vent Parts.

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 be opened

Direct Vent Only: 12 inches (30 cm)

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 soffit 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 soffit		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 floor.

4.For clearances not specified 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 specified 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

Page 9

Figure 9. Clearance from Overhang.

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

Figure 12. Vertical Vent Terminal Placement.

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 fittings 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 fittings, 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 fittings 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

Dimensions shown in inches.

Figure 13. 3" Vent Parts.

Endurance	Page 11


Minimum clearance from
combustibles (vent) U.S.*	3"	8cm
Minimum clearance from
combustibles (vent) Canada	6"	15cm
Max. flue 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.

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 flue 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 flue 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 unconfined spaces in buildings, infiltration may be adequate to provide air for combustion and ventilation. However, in buildings of unusually tight construction, or when locating the appliance in a confined 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 confined space shall be provided with two permanent openings communicating directly with other spaces of sufficient volume so that the combined volume of all such spaces meets the criteria for an unconfined 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 confined 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.Two 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	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 confined 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" flue opening (see Figure 14). The rest of the 3" vent system can be connected to the adapter within the

2400-415.

2.4Non-Concentric Combustion Air

An alternate, non-concentric combustion air

source may be installed (as shown in Figure 15),

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 qualified air space (see Section 2.3) or outside.

Separated combustion air / flue gas may be considered either “mechanical draft” or “direct vent”. To be considered “direct vent”, all of the combustion air and flue 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.

		2400-426
	3" vent termination
	3" diameter vent	with screen
	(50 equivalent feet, maximum)	with screen
2400-435 tee	(50 equivalent feet, maximum)
(to separate
venting from		vent
combustion		gases
air)
	4" combustion air pipe
	(15 equivalent feet, maximum)	combustion
		air

4" air terminal (field-supplied)

Combustion

Chamber

Non-Concentric Direct Vent with

Horizontal Vent.

Fan

2400-416 concentric rain cap (use only on systems

with condensate trap)		2400-370
with condensate trap)		vertical vent cap
		vertical vent cap
		(can be used on system with
		or without condensate trap)
	2400-409 condensate trap
2400-435 tee		(used if vent height is
2400-435 tee		greater than 7 feet)
(to separate		greater than 7 feet)
(to separate
venting from		4" combustion air pipe	combustion
combustion air)		4" combustion air pipe	combustion
combustion air)			air
			air
		4" air terminal
		(field-supplied)
	Combustion	Non-Concentric Direct Vent with
	Chamber	Non-Concentric Direct Vent with
	Chamber	Vertical Vent.
		Vertical Vent.
	Fan

Figure 15. Non-Concentric Combustion Air.

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.

3.1Gas 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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