NOH Vntg & Cmbstn

VENTING AND VENTING AND

COMBUSTION AIRCOMBUSTION AIRRoberts Mechanical Equipment Co.Roberts Mechanical Equipment Co.

WWW.ROBERTSMECH.COM WWW.ROBERTSMECH.COM

ANSI CATEGORIESANSI CATEGORIES

II

III

IV

ANSI Categories ANSI Categories

will tell you a great will tell you a great

deal about the deal about the

boiler and the boiler and the

application.application.

I


Understand the TableUnderstand the Table

Left side indicates a Left side indicates a

negative pressure.negative pressure.

Right Side indicates Right Side indicates

a positive pressure.a positive pressure.II

III

IV

I


Understand the TableUnderstand the Table

Top indicates nonTop indicates non--

condensing condensing

appliance (85% or appliance (85% or

less).less).

Bottom indicates Bottom indicates

condensing condensing

appliances (86% or appliances (86% or

more).more).

II

III

IV

I


Examples (negative)Examples (negative)

Atmospheric Atmospheric

Some fan assistedSome fan assisted

Masonry Chimney Masonry Chimney

BB--Vent materialVent materialII

III

IV

I


Examples (Positive)Examples (Positive)

Forced Draft Forced Draft

Side wall ventedSide wall vented

In line fan In line fan

UL Pressure stack or UL Pressure stack or

welded steelwelded steel

II

III

IV

I


Condensing / NonCondensing / Non--CondensingCondensing

Effect of Inlet Water Temperature to Boiler EfficiencyEffect of Inlet Water Temperature to Boiler Efficiency

natural gas = 1050 Btu/ftnatural gas = 1050 Btu/ft

inlet water temperatureinlet water temperature

boile

r efficien

cy, %

boile

r efficien

cy, %

1801804040 1301308080

100100

8686

9494

condensing boilercondensing boiler nonnon--condensing boilercondensing boiler

dew pointdew point

8080

II

III

IV

IWWW.ROBERTSMECH.COM WWW.ROBERTSMECH.COM

Lining A Masonry Lining A Masonry

Chimney (Cat. I)Chimney (Cat. I)

Atmospheric Atmospheric –– Clay Clay

Tile Liner Tile Liner

Fan Assisted Fan Assisted –– Clay Clay

Tile Liner (Interior) Tile Liner (Interior)

Metal Liner (Exterior)Metal Liner (Exterior)

Exception: Clay tile liner can

be used with exterior chimney

if an Atmospheric appliance is

connected to the same chimney

II

III

IV

I

Reference: ANSI Z223.1-2002 10.4.1

and 13.1.9, NFPA211 4-2.2



Chimney (Category III)Chimney (Category III)

Forced Draft Forced Draft –– Welded Welded

Steel, Pressure Stack, Steel, Pressure Stack,

or Inner Liner of or Inner Liner of

Pressure Rated StackPressure Rated Stack

II

III

IV

I


and 13.1.9, NFPA211 4-2.2



Chimney (Category II)Chimney (Category II)

Fan AssistedFan Assisted––

(85%+ Combustion (85%+ Combustion

Efficiency) AL29Efficiency) AL29--4C4CII

III

IV

I


and 13.1.9, NFPA211 4-2.2



Chimney (Category IV)Chimney (Category IV)

Fully Condensing Fully Condensing ––

AL29AL29--4C4C

II

III

IV

I


and 13.1.9, NFPA211 4-2.2


Safe Venting by CodeSafe Venting by Code

• Horizontal distances

• Large stack area

• Self venting connector rise

• Fan Min capacities

• Different type of appliances

• Existing masonry chimneys

• Location of draft inducer

National Fuel Gas Code

NFPA54 * IAS (A.G.A.) * ANSI Z 223.1


Common ViolationsCommon Violations

10.6.1.4 The total horizontal

distance of a vent plus the

horizontal vent connector

serving draft hood-equipped

appliances shall not be greater

than 75 % of the vertical height

of the vent.

Table 13.1 and 13.2 The total

horizontal length of the vent

plus the vent connector for a

single Category I appliance is:

100% of the height (vent 6 –

30 ft high); 30 ft (vent 31 – 50

ft high); 50% of the height

(vent 51 – 100 ft high)

(NFPA 54) Z223.1-2002

(Venting of Equipment)

Height

of

Vent

Not Greater than 75%

of the Vertical Height



13.2.2 The maximum vent

connector horizontal length

shall be 18 in./in of

connector diameter.

13.2.4 The length of the

common vent manifold

shall not exceed 18 in./in.

of common vent diameter.

13.2.5 The horizontal

length of the common vent

offset shall not exceed 18

in./in. of common vent

diameter.

(NFPA 54) Z223.1-2002 13.2

(Sizing of Venting Systems)

Diameter

18 inches per inch

3" 4" 5" 6" 7" 8" 9" 10" 12" 14" 16" 18" 20" 22" 24"

4.5' 6' 7.5' 9' 10.5'12' 13.5'15' 18' 21' 24' 27' 30' 33' 36'



(NFPA 54) Z223 Sizing Tables

1’ Min. (3”-10” diameter)

2’ Min. (12”- 18” diameter)

4’ Min. (20” and above)



13.2.17 Where two or more

appliances are connected

to a vertical vent or

chimney, the flow area of

the largest section of

vertical or chimney shall

not exceed seven times the

smallest listed appliance

categorized vent areas,

flue collar area, or draft

hood outlet area unless

designed in accordance

with approved engineering

methods.

(NFPA 54) Z223.1-2002 13.2.17

(Sizing of Venting Systems)

Outlet Diameter

Not Greater than 7 Times

the Smallest Outlet Area

3" 4" 5" 6" 7" 8" 9" 10" 12" 14" 16"

7" 10" 12" 14" 18" 22" 22" 26" 30" 36" 42"



10.10.4.2 Vent

connectors serving

Category I appliances

shall not be connected

into any portion of

mechanical draft

systems operating

under positive static

pressure, such as those

serving Category III or

Category IV appliances.

(NFPA 54) Z223.1-2002

10.10.4.2 (Venting of Equipment)



10.5.4.3 Masonry

chimneys shall be built

and installed in

accordance with NFPA

211.

4-2.2 Masonry

chimneys shall be

lined….Cat II, III and IV

gas appliances - special

gas vents listed for

installation within

masonry chimneys.

(NFPA 54) Z223.1-2002 10.5.4.3

(NFPA 211) 4-2.2



10.3.3 Forced draft systems

and all portions of induced draft

systems under positive pressure

during operation shall be

designed and installed so as to

prevent leakage of flue or vent

gases into a building.

10.3.4 Vent connectors serving

equipment vented by natural

draft shall not be connected into

any portion of mechanical draft

systems operating under

positive pressure.

(NFPA 54) Z223.1- 2002 10.3

(Mechanical Draft Systems)


Resolving Codes using Resolving Codes using

Mechanical Draft SystemMechanical Draft System

503.6.9.3 Mechanical draft.

Chimney venting systems using

mechanical draft shall be sized

in accordance with approved

engineering methods.

10.5.3.1 Size of Chimneys.

Chimney venting systems using

mechanical draft shall be sized

in accordance with approved

engineering methods.

International Fuel Gas

Code - Section 503

(Venting of Equipment)

International Fuel Gas International Fuel Gas

CodeCode -- Section 503 Section 503

(Venting of Equipment)(Venting of Equipment)

Z223.1- 2002

Standard for Venting

of Equipment

Z223.1Z223.1-- 2002 2002

Standard for Venting Standard for Venting

of Equipmentof Equipment


Mechanical Draft SystemMechanical Draft System

(Check List)(Check List)

�System should be UL listed (as

a designed system).

�System must Monitor proper

draft at all times.

�System must interlock, alarm

and lock out appliances.

�System must be supplied with

engineering (Acceptable

Engineering Method) specific to

installed appliances.

�System should modulate to

match today’s efficient

appliances.

�System performance should be

guaranteed.


Vent Category ReviewVent Category Review

CategoryCategory CharacteristicCharacteristic TypeType DraftDraft VentVent

II

IIII

IIIIII

IVIV

Non-

Condensing

Negative

pressure

Natural draft

appliance and

fan assisted

< 86 % efficient

Draft hood:

Negative

Fan-assist: - 0.02

to - 0.08

B-Vent

Condensing

Negative pressure

Fan assisted

appliance

> 86 % efficient

Fan-assist:

- 0.02 to -

0.08

AL29-4C

Non-Condensing

Positive pressure

Forced draft /

Direct Vent

< 86 % efficient

Positive

Forced Draft

(Pressure

stack) Direct

Vent (AL29)

Condensing

Positive pressure

Fan assisted/

Pulse

Positive AL29-4C


Combustion AirCombustion Air



CodeCode

8.3.3.2 One Permanent Opening Method: One permanent

opening, commencing within 12 in. of the top of the

enclosure, shall be provided. 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

the following:

1 in.²/3000 Btu of the total input rating of all equipment

located in the enclosure, and not less than the sum

of the areas of all vent connectors in the space.

8.3.3.2 One Permanent Opening Method: One permanent 8.3.3.2 One Permanent Opening Method: One permanent

opening, commencing within 12 in. of the top of the opening, commencing within 12 in. of the top of the

enclosure, shall be provided. The opening shall enclosure, shall be provided. The opening shall

directly communicate with the outdoors or shall directly communicate with the outdoors or shall

communicate through a vertical or horizontal duct to communicate through a vertical or horizontal duct to

the outdoors or spaces that freely communicate with the outdoors or spaces that freely communicate with

the outdoors and shall have a minimum free area of the outdoors and shall have a minimum free area of

the following:the following:

1 in.1 in.²²/3000 Btu of the total input rating of all equipment /3000 Btu of the total input rating of all equipment

located in the enclosure, and not less than the sum located in the enclosure, and not less than the sum

of the areas of all vent connectors in the space.of the areas of all vent connectors in the space.

Z223.1Z223.1--2002 8.3.3 Outdoor Combustion Air2002 8.3.3 Outdoor Combustion Air.


Sizing Combustion Air Sizing Combustion Air

Louvers (Gravity)Louvers (Gravity)

Louver(s) Sizing:

1 sq.in./4000 Btu per louver1 sq.in./4000 Btu per louver

4000 MBH = 1000 in24000 MBH = 1000 in2

of of freefree area per louver.area per louver.

Typical louver has 30-60%

free area.

Depending on louver design Depending on louver design

actual louver size will be:actual louver size will be:

Using 45% free area Using 45% free area

louverslouvers

= Two 5= Two 5’’ x 4x 4’’

louverslouvers

2000

MBH

2000

MBH

Tip: Check with the Louver Manufacturer for accurate Tip: Check with the Louver Manufacturer for accurate ‘‘free free

spacespace’’ than watch equal products in the submittals.than watch equal products in the submittals.


Combustion Code Combustion Code

Summery.Summery.

NFPA 54

gas

NFPA 31

oil

BOCA

all

SBCCI

gas & oil

SBCCI

solid

Minimum No. openings required 2 2 2 2 2

Outdoor opening, sq. in./Btuh 1/4000 1/4000 1/4000 1/4000 2/1000

Vertical ducts, sq. in./Btuh 1/4000 1/4000 1/4000 1/4000 -

Horizontal ducts, sq. in./Btuh 1/2000 1/2000 1/2000 1/2000 -

Ducts same as opening yes yes - yes -

Minimum duct dimension, inches 3 3 3 3 3

Louver & grill free area opening opening - - opening

Free area allowance, wood* 20-25% 20-25% 25% - -

Free area allowance, metal* 60-75% 60-75% 75% - -

Damper interlocked yes yes yes - -

*use manufacturer's free area rating when available.


Below Grade Mechanical Below Grade Mechanical

RoomsRooms

�Total fuel input rate of all

fuel-burning devices located

in the boiler room

considered.

�The Btu rate per hour of all

boilers at maximum burning

rate, plus other devices such

as water heaters, are used to

size air openings.

�Outside air openings sizing

must be done based on its

free area. (Protective mesh

must be no smaller than 0.25

inch to minimize dirt build-up

or obstruction.


Direct Connect Direct Connect


�Best with Fan

Assisted

Appliances.

�Roof or Single side.

�Careful combining

Combustion air

intakes.

�Watch Horizontal

lengths (fitting

equal 10’).

�FREEZE

PROTECTION

Tip:Tip: Freeze protection should be proven damper

system operating in the specific boiler sequence.

Allows combining inlet also prevent freezing

without power.



CodeCode

8.3.6 Mechanical Combustion Air Supply. Where all combustion

air is provided by a mechanical air supply system, the

combustion air shall be supplied from outdoors at the

minimum rate of 0.35 ft³/min per 1000 Btu/hr for all

appliances located within the space.

8.3.6.1 Where exhaust fans are installed, additional air shall be

provided to replace the exhausted air.

8.3.6.2 Each of the appliances served shall be interlocked to the

mechanical air supply system to prevent main burner

operation where the mechanical air supply system is not in

operation.

8.3.6 Mechanical Combustion Air Supply. Where all combustion 8.3.6 Mechanical Combustion Air Supply. Where all combustion

air is provided by a mechanical air supply system, the air is provided by a mechanical air supply system, the

combustion air shall be supplied from outdoors at the combustion air shall be supplied from outdoors at the

minimum rate of 0.35 ftminimum rate of 0.35 ft³³/min per 1000 Btu/hr for all /min per 1000 Btu/hr for all

appliances located within the space.appliances located within the space.

8.3.6.1 Where exhaust fans are installed, additional air shall b8.3.6.1 Where exhaust fans are installed, additional air shall be e

provided to replace the exhausted air.provided to replace the exhausted air.

8.3.6.2 Each of the appliances served shall be interlocked to th8.3.6.2 Each of the appliances served shall be interlocked to the e

mechanical air supply system to prevent main burner mechanical air supply system to prevent main burner

operation where the mechanical air supply system is not in operation where the mechanical air supply system is not in

operation.operation.

Z223.1Z223.1--20022002


Mechanical Mechanical


� Guaranteed to

provide proper

combustion air.

� Small opening /

more aesthetic.

� Solves Code

Issues

Tip:Tip: Multiple water heaters or boilers running

high efficiency firing rates warrant a modulating

combustion air system.


Sizing Mechanical Sizing Mechanical


Louver Sizing:

Engineered using ASHRAE

Chimney Design

Equation.

Flue Gas Volume corrected

for temperature = 1,400

cfm of combustion air

1400 cfm/500 fpm = 2.8 ft2 of

louver free area

Using a 45% free area louver

= One 3’ x 2’ louver

Tip:Tip: Be sure to consider any mechanical exhaust in the boiler.

Fan must keep up with all ventilation as well.

2000

MBH

2000

MBH


The Barometric DamperThe Barometric Damper

NORMAL OPERATION

Barometric Damper is weighted

to open and ‘break’ draft by

mixing a % of room air.

The chimney is drawing at a

specific rate, but now draws

from the water heater/boiler

and room.

Typical draft for negative

commercial appliances is -.02

to -.08.

Tip:Tip: Use a barometric damper on stacks over 25’ or 30’ as

long as the appliance is category I or II (negative).


The Barometric DamperThe Barometric Damper

NEGATIVE MECH ROOM:

� Room goes negative.

� Barometric is pulled into the

room.

� The barometric becomes a

source of make up air for

the room.

� Problem is, this make up air

is deadly.

Tip:Tip: Pay close attention to the combustion air in a room.

Look for sources of problems such as old leaky returns.


Thank You!Thank You!

More Information / Additional Training:

Roberts Mechanical Equipment

P: 216-587-0005

F: 216-587-0008

Or visit our industry leading web site at:

www.robertsmech.com

More Information / Additional Training:More Information / Additional Training:

Roberts Mechanical EquipmentRoberts Mechanical Equipment

P: 216P: 216--587587--00050005

F: 216F: 216--587587--00080008

Or visit our industry leading web site at:Or visit our industry leading web site at:

www.robertsmech.comwww.robertsmech.comWritten by/Property of: Grant RobertsWritten by/Property of: Grant Roberts


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