”Venting-on-Demand”Minimizing Energy Loss through the Exhaust Ventilation Systems in order to meet Sustainable Design Standards

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Appliance Categories

ASHRAE Chimney Design Equation

Gravity Venting vs. Mechanical Venting

Common Code Violations

Combustion Air Supply

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Controlled Venting Natural VentingVersus

Controlled Air Supply Natural Air SupplyVersus

Combined Venting Individual VentingVersus

= Sustainable Designs

ApproachApproach

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Hotels

Hospitals

Applications

Schools

Sports Arenas

Museums

Apartments / Condominiums

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National Fuel Gas Code

• Category I

• Category II

• Category III

• Category IV

NFPA 54

IAS (A.G.A.)

ANSI Z 223.1

Appliance CategoriesAppliance Categories

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ANSI Venting Categorization

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Appliance CategorizationAppliance Categorization

IV

III

II

I

Atmospheric

Fan Assisted(high

efficiency)

Forced Draft

Condensing

Draft Hood

Fan AssistedDraft Diverter

Scotch Marine

Negative Positive

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Z223.1Z223.1--54 (Venting of equipment)54 (Venting of equipment)

12.1 Minimum Safe Performance

A venting system shall be designed and constructed so as to develop a positive flow adequate to remove flue or vent gases to the outside atmosphere.

12.4.1 Equipment Draft Requirement

A venting system shall satisfy the draft requirement of the equipment in accordance with the manufacturer’s instructions.

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Chimney Design EquationChimney Design Equation

1996 Edition

INPUTS:• Appliance Type• Fuel Type• MBH Input• CO2% in Flue Gases• Flue Gas Temperature• Ambient Temperature• Altitude• Flue Layout

RESULTS:• Flue Gas Volume• Flue Gas Velocity• Theoretical Draft• Total Pressure Losses• Appliance Outlet Pressure

OutletPressure

PressureLosses (+)

+

TheoreticalDraft (-)

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Draft Variations During OperationDraft Variations During Operation

Vent = 30’ vert./10’ horiz., 18” diam.

4 Fan-assisted Cat I boilers with 1,000 MBH input each

Constant ambient of 60°F

Draft requirement: 0.05”WC

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Boiler Efficiency versus DraftBoiler Efficiency versus Draft

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Mechanical Draft SystemMechanical Draft System

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Mechanical Draft System Mechanical Draft System –– Sidewall Sidewall

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Mechanical Draft Systems

(CASV)

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CASI - Chimney Automation System

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Modulating Overdraft Damper System

MDF

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Green Building DesignGreen Building Design

• Perfect combustion for CAT III boilers are 3% O²

• Only possible at single boiler installation with “Stub stack”

• Fluctuation in gravity venting leading to combustion O²-levels set between 4.5 – 6.5% to avoid soothing

• Efficiency losses between 3 –15%

Economical

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Green Building DesignGreen Building Design

Economical

Boiler Capacity Efficiency Rating

EfficiencyLoss %

Efficiency Loss Efficiency Loss per Year In $ (*)

3,000 MBH 85% 3.5% 1.5 Therm/Hrs $ 5,400

6,000 MBH 85% 6.0% 2.9 Therm/Hrs $ 10,500

10,000 MBH 85% 8.0% 9.5 Therm/Hrs $ 34,000

Unit Price: $ 1.20 per ThermRunning Time: 3,000 Hours per Year

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National Fuel Gas Code National Fuel Gas Code

NFPA 54

IFGC

ANSI Z 223.1

• Horizontal distances• Large stack area• Self venting connector

rise• Fan Min capacities• Different type of

appliances• Existing masonry

chimneys• Location of draft

inducer

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Aesthetical

““InvisibleInvisible”” ExhaustExhaust

• A natural draft chimney must terminate at least 2 feet above anything within 10 feet.

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What code violation????What code violation????

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Aesthetical

““InvisibleInvisible”” ExhaustExhaust

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Design

Minimal Design RestrictionsMinimal Design Restrictions

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Space Saving

Minimize Stack ShaftMinimize Stack Shaft

• A chimney must be designed for the maximum input of all the heating appliances it serves.

• A naturally vented heating appliances should be vented by its own chimney.

MCASMCASMechanical Combustion Air SupplyMechanical Combustion Air Supply

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Code Requirements – Air for Combustion and Ventilation

9.3.3.1 Two Permanent Openings Method. Two permanent openings, one commencing within 12 in. of the top and one commencing within 12 in. of the bottom of the enclosure, shall be provided. The openings shall communicate directly, or by ducts, with the outdoors or spaces that freely communicate with the outdoors as follows:

(1) Where directly communicating with the outdoors or through vertical ducts, each opening shall have a minimum free area of 1 in.²/4000 Btu of total input rating of all equipment in the enclosure.

(2) Where communicating with the outdoors through horizontal ducts, each opening shall have a minimum free area of not less than 1in.²/2000 Btu of total input rating of all equipment in the enclosure

Codes and StandardsCodes and StandardsCodes and Standards

• Z223.1-2006 9.3.3 Outdoor Combustion Air.

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Louver(s) Sizing:• 1 sq.in./4000 Btu per louver

4000 MBH = 1000 in2

of free area per louver.

• Typical louver has 30-60% free area.

• Depending on louver design actual louver size will be:

Using 45% free area louvers= Two 5’ x 4’ louvers

Codes and StandardsCodes and Standards

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WhereWhere’’s the Louver???s the Louver???

Sub Title9.3.6 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.

9.3.5 Engineered combustion air installations shall provide an adequate supply of combustion, ventilation and dilution air.

Codes and StandardsCodes and StandardsCodes and Standards

• Z223.1-2006

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2000 MBH2000 MBH

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

Sizing of Mechanical Combustion Air

Codes and StandardsCodes and Standards

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”Venting-on-Demand”Minimizing Energy Loss through the Exhaust Ventilation Systems in order to meet Sustainable Design Standards

Exhaust Air Supply

Concepts - technology

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