A. O. Smith GB-1300 Installation Manual

Genesis Engineering and Design Manual

Introduction

Engineering and Design Manual

Dear A. O. Smith Customer,

This Engineering and Design Manual has been written to aid in designing and specifying

A. O. Smith Genesis hydronic heating boilers. This manual is intended to quickly and easily

answer the most frequently asked questions regarding the Genesis product line.

This manual is intended for use by professional designers and engineers and is not meant

to be all inclusive. Reference should be made to the instruction manual accompanying the

product. This Engineering and Design Manual contains supplemental information to the

Genesis Instruction and User’s Information Manual. A copy of the complete instruction manual

can be obtained from the A. O. Smith website (www.hotwater.com), from the A. O. Smith

Customer Care Center at 1-800-527-1953, or from your local A. O. Smith Representative.

A. O. Smith is proud of our quality products, and we appreciate your interest in our

products. We hope to be working with you soon.

Sincerely yours,

A. O. Smith Water Heaters

Table of Contents

CHAPTER 1 - BASICS OF INSTALLATION .............................................................................5-6

Code Compliance............................................................................................................5

Location...........................................................................................................................5

Installation Clearances....................................................................................................5

CHAPTER 2 - SPECIAL SITUATIONS......................................................................................7-8

Installation on Combustible Flooring...............................................................................7

Outdoor Units ..................................................................................................................7

CHAPTER 3 - COMBUSTION AIR..........................................................................................9-12

Sizing Combustion Air Louvers.......................................................................................9

Combustion Air and the Genesis Boiler..........................................................................9

or Combustion (Through the Wall)..........................................................................10

Air f

Air for Combustion (Vertical Ducts)...............................................................................10

Air for Combustion (Horizontal Ducts) ..........................................................................11

Alternate Air f

or Comb

ustion.........................................................................................11

CHAPTER 4 - SPECIAL PROBLEMS - COMBUSTION AIR ...............................................13-14

Boiler Room Exhaust Fans ...........................................................................................13

Contaminated Combustion Air ......................................................................................13

Flammable Items...........................................................................................................14

CHAPTER 5 - VENTING SECTION.......................................................................................15-36

General Venting Information..........................................................................................15

enting Categor

Genesis

Genesis Boiler Category I Venting ................................................................................16

Natural Draft Vertical Venting Using Boiler Room Air for Combustion (Category I)......17

Masonr

Category I Common Venting Multiple Units ..................................................................18

Common Venting Genesis Boilers When Using A Stack-Rack.....................................19

Categor

Category I Vertical Direct Venting (Two Pipe System Using Outdoor Air) ....................21

Meeting Special State and Local Codes Requiring Direct Vent Sealed Combustion ...23

Category III One Pipe Sidewall Venting Using Boiler Room Air ...................................24

Category III Horizontal Two Pipe Direct Vent Using Outdoor Air ..................................25

Category III Extended Horizontal Sidewall And Direct Venting (Power Assist) ............27

Locating Exhaust and Comb Special

Category III - Genesis Venting ......................................................................................29

Termination Considerations...........................................................................................30

Type “B” Double Wall Vent Sizing Tables .................................................................31-35

y Chimne

y I Natural Draft Vertical Vent Termination........................................................20

ent Terminal Location Considerations ............................................................29

ys - Atmospher

ies and Venting Materials......................................................15

ic Dr

ustion Air

.......................................................................

aft

erminations ....................................................29

Genesis Engineering and Design Manual

Table of Contents

CHAPTER 6 - GAS SUPPLY......................................................................................................37

General Genesis Gas Supply Considerations .........................................................37-40

Single Boiler Gas Pipe Sizing .......................................................................................38

Gas System Sizing........................................................................................................38

Multiple Appliance Gas System Sizing - Natural Gas...................................................38

Multiple Appliance Gas System Sizing - Propane Gas.................................................39

High Altitude Installations..............................................................................................39

General Altitude Information .........................................................................................39

High Altitude Sizing Considerations..............................................................................40

Genesis Pre-Jet Orifices ...............................................................................................40

CHAPTER 7 - GENESIS ELECTRICAL REQUIREMENTS.......................................................41

CHAPTER 8 - HYDRONIC HEATING SYSTEMS & COMPONENTS...................................43-45

Genesis Boilers .............................................................................................................43

Boiler & System Water Flo

Boiler Temperature Settings ..........................................................................................44

Hydronic Heating System Components

w Requirements..................................................................43

........................................................................44

CHAPTER 9 - HYDRONIC HEATING SYSTEM PIPING ......................................................47-57

Primary/Secondary Piping ............................................................................................47

Primary/Secondary Piping Multiple Boilers...................................................................48

Boiler Oper

Minimum System/Boiler Temperature ...........................................................................49

Locating the System Temperature Sensor ....................................................................49

imar

For Design Temperatures of 180°F or Less..................................................................50

For Design Temperatures Over 180°F ..........................................................................51

or Design

Understanding Cast Iron and Steel Boiler Systems with Three-Way Mixing Valves.....53

Efficiency of Low Mass vs. High Mass Boilers..............................................................53

Retrofitting A Cast Iron Boiler

Boiler System ................................................................................................................54

Special Cases - Piping Low or Varied Flow Systems ...................................................56

INDEX OF FIGURES ..................................................................................................................58

ABLES

INDEX OF

ating Temperature Controls.........................................................................48

y/Secondar

.....................................................................................................................59

y - Multiple Boiler Piping Configurations.....................................50-52

F ........................................................................52

emper

atures Belo

w 120

With Three-Way Mixing Valve To A Copper

Basics of Installation

Air Inlet

Alternate Air Inlet

xhaust Vent

Alternate Exhaust Vent

Gas Connection

odels 200 thru 500

Gas Connection Models 650 & 750

Control Board Access Door

On/Off

witch

Flow Switch Factory Mounted

Factory Sized and Mounted Pump (Standard GW Water Heaters, Optional GB Boiler Models)

Control Box Access Door

Genesis Boiler Points of Reference

Exhaust Vent

Alternate Exhaust Vent

Pressure Relief Valve

Water Outlet

Dia-Scan II User Interface & Digital Readout

Control Board Access Door

Genesis Models GB-300 thru 750

Control Board Access Door

Air Inlet

Water Inlet

View Port

On/Off Switch

Electrical Connection Boxes

al Boiler Mounted Pump

Integ (Standard GW Water Heaters, Optional GB Boiler Models)

Control Box Access Door

Pressure Relief Valve

Water Outlet

Dia-Scan II User Interface

Digital Readout

Exhaust Vent

Left or Right Hand Gas Connections

Genesis Models GB-1000 thru 2500

Figure 1-1

Water Inlet

View Port

Integral Boiler Mounted Pump (Standard GW Water Heaters, Optional GB Boiler Models)

Genesis Engineering and Design Manual

CHAPTER 1. BASICS OF INSTALLATION

Code Compliance

The Genesis boiler design complies with the

latest edition of the American National Standards

Institute for gas-fired, low-pressure steam and hot

water boilers, ANSI Z21.13 and CSA 4.9.

In addition to the information in the instruction

manual, the boiler(s) shall be installed in strict

accordance with those installation regulations in

force in the local area where the installation is to

be made

consulted bef

absence of local codes

comply with the latest editions of:

. Author

ities having jurisdiction should be

ore installations begin. In the

, the installation m

ust

the piping system as possible. This location

should also be such that the gas ignition system

components are protected from external dripping

and spraying of water during appliance operation

and service.

Additional boiler location considerations:

• The boiler must not be installed on carpeting

(See Chapter 2).

• The boiler should not be located in an area

where it will be subject to freezing.

• The boiler should be located near a floor drain.

• The boiler should be located in an area where

leakage from the boiler or connections will not

result in damage to the adjacent area or to

lower floors of the structure.

In the United States:

The National Fuel Gas Code, ANSI

Z223.1/NFP

Electr

The installation Code CAN/CSA B149.1-00

Electric Code, CSA C22.1.

A 54 and the National

ic Code, NFPA 70.

In Canada:

and the Canadian

Location

Before installing any boiler, careful

consideration must be given to proper location.

The location selected should be as close to the

stack or chimney as practical, offer adequate

make-up air supply, and be as centralized within

Note: When such locations cannot be avoided,

a suitable drain pan should be installed under

the boiler. Drain pans should be fabricated with

sides at least 2

width at least 2 inches greater than the

dimensions of the boiler. The drain pan must be

piped to an adequate drain and must not restrict

combustion air flow.

⁄2 inches deep, with length and

Installation Clearances

Sufficient area should be provided at the front

and sides of the unit for proper servicing. For ease

of service, minimum clearances of 24 inches in

the front and 18 inches on the water connection

side are recommended.

Basics of Installation

Please note that the minimum clearances

shown are the certified minimum clearances.

Whenever possible, additional space is

recommended. Genesis boilers are approved for

installation on noncombustible flooring in an

alcove with minimum clearance to combustibles.

For installation on combustible flooring, see

Chapter 2 Special Situations.

Figure 1-2 Figure 1-3

(Table A) Minimum Clearances to Combustibles

Clearances

Left Side A

Rear B 3" 3"

Right Side C 3" 3"

Top D 3" 6"

Front

Vent 6" 6"

Hot Water Pipes 2" 2"

Location

Figure 2 & 3

Models GB/GW-400 - 750

3" 12"

(18" for Service) (18" for Service)

Alcove Alcove

(24" for Service) (24" for Service)

Models GB/GW-1000 -

2500

Genesis Engineering and Design Manual

CHAPTER 2. SPECIAL SITUATIONS

Installation on Combustible Flooring

For installation on combustible flooring, use

the Combustible Floor Shield Kit.The combustible

floor kit base adds 4˝ to the overall height of the

boiler. See Figure 2-1. (See Table B for kit part #).

Genesis on

Combustible Floor Shield

concrete pad. The concrete pad must be at least

12 inches larger than the boiler footprint on all four

sides of the boiler.

For rooftop installations use the combustible

floor base (see Figure 2-1 and Table B for kit part #).

• An outdoor model Genesis boiler should not

be located in an area where high winds can

cause a down draft by rolling off walls,

buildings, shrubbery, inside corners, or roof

overhangs. The boiler should be a minimum

of 6 feet away from such structures if high

winds are prevalent in the area.

Table B - Combustible Floor Shield Kit #

Outdoor Units

ed f

Smith Genesis boilers are appro

outdoor installation ONL

Outdoor units require additional

kits

consider

this engineer

the Instr

ations that will not be fully discussed in

ing and design man

uction Man

issues are addressed belo

Y with appro

or full details

ual f

ual.

Primary Outdoor Issues:

The outdoor boiler cannot be installed directly on

the ground.

The boiler m

ust be installed on a

ed outdoor

Please see

Only pr

imar

Model # A.O. Smith Part #

GB-300 9500007275

GB-400 210202-002

GB-500 9003670001

GB-650 210202-004

GB-750 9500007276

GB-1000 21

GB-1300 211093-001

GB-1500 21

GB-1850 211093-003

GB-2100 211093-004

GB-2500 211093-005

1093-000

1093-002

Special Situations

• Outdoor units should never be installed

under roof overhangs where water from the

roof can fall directly on the unit. Install at least

3 feet away from the drip line of the roof

overhang.

• Special considerations apply in areas where

freezing temperatures are encountered.

Genesis boilers in hydronic heating

applications must use a glycol mixture. In

addition, for Genesis boilers used in a potable

domestic hot water application, the boiler pump

delay setting must be set to “constant run.”

Note: If any potable domestic hot water heating

system must be shut down for service during cold

weather, shut off the water supply, then drain the

boiler, piping, and pump. Additional freeze

protection measures such as automatic drain

systems should also be considered.

Genesis Engineering and Design Manual

CHAPTER 3. COMBUSTION AIR

Figure 3-1 Combustion Air

Combustion Air

Complete combustion requires 10 cubic f

of air per 1000 BTU per hour gas input. The

National Fuel Gas Code also recommends an

“excess”

additional 2.5 cubic f

cubic f

gas input is the recommended minimum

combustion air supply required to ensure

complete combustion for natural and propane gas

equipment. (See Figure 3-1).

minimum make-up air opening sizes for various

building installations. (Ref: NFPA 54/ANSI

Z223.1, sec. 5.3 or CAN/CSA B149.1-00).

eet of make-up air per 1000 BTU per hour

The National Fuel Gas Code specifies

eet of

air. This 12.5

eet

should be considered.

mesh smaller than 1/4-inch square

area is not kno

National Fuel Gas Code ANSI Z223.1

recommends using figures of 20-25 percent free

area for wood louvers, or 60-75 percent for metal

illes or louv

wn, the current edition of the

ers

Screens shall not be of

. If the free

Combustion Air and the Genesis Boiler

When installing the Genesis in an area of tight

uction or within a

constr

than 50 cubic f

the total input r

that space), adequate comb

eet of volume per 1,000 BTU/H of

ating of all appliances installed in

“confined” air space (less

ustion air must be

Sizing Combustion Air Louvers

To calculate the free area of a vent opening,

the blocking effect of screens, louvers, and grilles

supplied to the boiler

from NFP

explains various methods of meeting the

minimum air requirements for these installations.

A 54, ANSI Z223.1, 1996, Sec., 5.3

. The following information

Combustion Air

Air for Combustion (Through the Wall)

The Genesis is installed as a Category I

appliance when it is vented vertically and is using

boiler room air for combustion. (Can use standard

type “B” vent material when installed in this

configuration.) A fresh supply of make-up air for

combustion can be supplied to the boiler through

make-up air ducts which directly communicate

with the outdoors. Two openings are required: one

Figure 3-2 Air for Combustion

(Through the Wall)

within 12 inches of the top of the enclosure and

one within 12 inches of the bottom of the

enclosure. Each opening shall have a free area

of not less than 1 square inch per 4000 BTUH of

the total input of all appliances within the enclosure.

Air for Combustion (Vertical Ducts)

The lower opening is primarily providing

combustion air. The upper opening is providing

vent dilution air and acts as a relief opening f

flue gases in the event that the vent becomes

obstructed or a do

wndraft condition occurs.

Figure 3-3 Air for Combustion (Vertical Ducts)

Often it is more practical to install vertical

make-up air ducts, as shown in Figure 3-3, to the

outdoors. Again, two openings are required: one

within 12 inches of the top of the enclosure and

one within 12 inches of the bottom of the

enclosure. Each opening shall have a free area

of not less than 1 square inch per 4000 BTUH of

the total input of all appliances within the

enclosure.

Figure 3-4 Air for Combustion (Horizontal Ducts)

Air for Combustion (Horizontal Ducts)

Genesis Engineering and Design Manual

When the boiler is installed in an inter

ertical ducts, horizontal

with no roof access f

make-up air ducts should be installed.

using horizontal ducts, two openings are required:

one within 12 inches of the top of the enclosure

or v

ior room

When

Alternate Air for Combustion

and one within 12 inches of the bottom of the

enclosure

of not less than 1 square inch per 2000 BTUH of

the total input of all appliances within the

enclosure.

. Each opening shall have a free area

Figure 3-5 Alternate Air f

Since the release of the 1996 edition, the

National Fuel Gas Code has allo

method of supplying air f

or combustion using a

wed a second

(Thr

ough the

single opening.

opening and is intended to help pre

damage to boiler room piping.

or Combustion

all)

This method uses a smaller

vent freeze

Combustion Air

Alternate Air for Combustion (continued)

Figure 3-6 Alternate Air for Combustion (Vertical Duct)

One permanent opening, commencing within

12 inches (30 cm) of the top of the enclosure,

shall be permitted where the equipment has

clearances of at least 1 inch (2.5 cm) from the

sides and back and 6 inches (16 cm) from the

front of the appliance. The opening shall directly

comm

unicate with the outdoors or shall

communicate through a vertical or horizontal duct

to the outdoors or spaces (crawl or attic) that

freely communicate with the outdoors, and shall

have a minimum free area of:

• 1 square inch per 3000 BTU/H (7cm

per kW)

of the total input rating of all equipment located

in the enclosure, and

• not less than the sum of the cross sectional

areas of all v

ent connectors in the confined

space.

Figure 3-7 Alternate Air for Combustion (Horizontal Duct)

CHAPTER 4. SPECIAL PROBLEMS –

COMBUSTION AIR

Boiler Room Exhaust Fans

Genesis Engineering and Design Manual

Insufficient make-up air is a major cause of

combustion problems. One common example is a

mechanical room where exhaust vent equipment

was not considered in sizing make-up air

requirements. This may result in air being pulled

down the exhaust vent of the Genesis causing flue

gas spillage, flame roll out, improper combustion

(sooting), and/or erratic boiler shut down.

Figure 4-1 Boiler Room Exhaust F

Contaminated Combustion Air

The quality of the combustion air is important

in all applications, including those involving direct

venting. Contaminants in combustion air can lead

to premature boiler failure. Vapors from

bleaches, soaps, waxes, salts, freon, (See

Figure 4-2) etc. are drawn into the combustion

chamber with the make-up air and, once fired,

mix with water vapor in the gases to form

extremely corrosive hydrochloric or hydrofluoric

acid and other corrosive by-products.

ans

Figure 4-2

Special Problems - Combustion Air

Flammable Items

Flammable items, pressurized containers or

any other potentially hazardous articles must not

be placed on or adjacent to the boiler. Open

containers of flammable material should not be

stored or used in the same room with the boiler.

Genesis Engineering and Design Manual

CHAPTER 5. VENTING SECTION

General Venting Information

The Genesis boiler is a fan-assisted

appliance, that offers many different venting and

combustion make-up air options and methods. It

has a sealed combustion chamber and can be

installed as a true Category III Direct Vent

Appliance. However, the Genesis unit can also be

installed in less stringent Category I

configurations. Whatever the configuration, you

must understand the following definitions in order

to proper

mak

application.

ly specify the venting and combustion

e-up air requirements for a particular

Definitions:

Fan Assisted Combustion

• A fan-assisted comb

ustion appliance is one

• Category III - A non-condensing gas

appliance that operates with a positive vent

pressure.

• Category IV - A condensing gas appliance

that operates with a positive vent pressure.

Genesis Venting Categories and Venting Materials

The Genesis boiler operates at an efficiency

of 83.7% (rounded to 84%), the highest efficiency

possible in a non-condensing boiler. At 83.7%, the

Genesis is operating near the threshold of

condensing. When vented vertically, the natural

draft and natural buoyancy of the hot flue gases

move the flue gases up the vent rapidly before the

gases can condense in the vent. This allows the

use of standard Type “B” venting material.

which has a f

A fan-assisted burner is defined as: “a burner

•

which uses either induced or forced draft.”

• A draft hood appliance can only be a

Category I appliance, while an appliance with

a fan-assisted burner may fall into any of the

four categories.

Gas Appliance Venting Categories Defined:

• Category I - A non-condensing gas appliance

that operates with a non-positive vent

pressure.

• Category II - A condensing gas appliance

that operates with a non-positive vent

pressure.

an-assisted burner.

However, when venting the unit horizontally,

and without the aid of a natural draft, the flue

gases move more slowly providing additional time

for the flue gases to cool, increasing the likelihood

of flue gases condensing in the vent. Therefore,

when venting mid-efficiency boilers, (such as the

Genesis) horizontally, AL29-4C stainless steel

venting material must be used to prevent damage

from corrosive condensate building up in the

vent. Such buildup in non-approved vent piping

will potentially result in deadly flue gases leaking

into the building or facility.

Venting Section

Genesis venting will fall into one of the four configurations as shown on Table C.

(Table C) Genesis Vent Categories and Materials

Source of Combustion

Air

Using Boiler Room Air

(Non - Direct Vent)

Using Outdoor Air Piped

Directly to the Boiler

(Dirct Vent)

Venting

Configuration

Vertical Venting

Natural Draft

Horizontal

Sidewall Venting

ertical Venting Category I

Horizontal

Sidewall Venting

Certified Venting

Genesis Boiler Category I Venting

Single Unit

The Genesis boiler uses fan assisted

ustion. When sizing the vent for a Genesis

comb

boiler in a natur

the “Fan” columns in the venting tables (see pages

al draft vertical vent system, use