Chimney Physics

Ashley Eldridge Chimney Safety Institute of America

This session is designed to help technicians understand how pressures (air flowing in and out of the home) can cause fuel burning equipment to malfunction. There will be case studies and solutions.

2017 HPBExpo Education Sponsored by:

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Chimney Physics

An Overview

Brought to you by the Chimney Safety Institute of America

© CSIA 2017

Today We Will Discuss How the Laws of Physics Affects Air

Movement in the Home.

We Will Cover:

- The House As a System

-Combustion Air Requirements

-Indoor Air Quality

U i h T l f h T d-Using the Tools of the Trade

-Troubleshooting Vented Appliances

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Course Content and Format

The longer Chimney Physics class has; • More material to provide a thorough

understanding of the issues.g• Practical exercises to give you real world

experience using the equipment necessary to complete the job.

• Handouts and materials that can be used in the field.

Who Should Be Taking the Course?

• This course is perfect for chimney sweeps, hearth products installers, HVAC technicians, designers, architects, and building officials.

• Anyone that is interested in having a better understanding of indoor air quality, house air flow and pressure issues, combustion air supply, vent design diagnosis of venting issues and implementation of solutions.

What Will I Take Home From This Class?

• Useful information that you can apply right away.

• A hunger to learn more and a desire to sign up for the extended class.

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Chimney Safety Institute of America

Reference Materials and Contributors

“Venting Design Specialist Training Manual”, Hearth Education Foundation.

“The Fireplace in the house as a system”, John Gulland.

Magic Sweep Corporation, Jim Brewer

Jack Pixley Sweeps, Inc., Jack Pixley

National Fire Protection Association, NFPA 211 Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances, 2016 Edition

Watch for This Image

• This icon means there is a handout to discuss.

Seminar Topics

• Venting designs• Flue sizing• System location

• Neutral pressure plane

• Venting problems

• Diagnostic testing• Pressure• Draft & flow• Combustion air• Air openings• Air flow

g g

• Sooting

• Ventilation

• Blower doors

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Venting Designs

Venting systems for Atmospherically vented appliances include;

•B-ventB vent

•Direct vent

•Factory built chimneys

•Masonry chimneys

Table ofContents

Obvious Problems

B-vent

Approved for many gas-fired hearth appliances such as:

•Gas inserts

•Gas stoves

•Gas fireplaces

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B-vent

• B-vent is constructed of two walls separated by a small air space.– Inner wall is aluminum.Inner wall is aluminum.

– Outer wall is galvanized.

• B-vent is inexpensive and easy to install.

• Tested to UL 441 – gas vents.

B-vent

• B-vent is not approved for use with vented gas logs.

• Flue gases could easily exceed the 470 degree temperature test of UL 441.

B-vent – Outdoors ?

• B-vent is not recommended for outdoor installation b l h flibelow the roofline.

• Low insulating value allows rapid cooling of flue gases.

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Direct Vent

• Direct vent appliances draw their combustion air from the outdoors, and exhaust combustion products directly to the p youtdoors.

Co-linear Direct Vent

• Co-linear DV systems use one pipe for exhaust and another f b i ifor combustion air.

• Practical for:– Inserts & Hearth stoves

– HVAC systems

Co-axial Direct Vent

• Co-axial DV systems use a “pipe within a pipe” design.

• Inner pipe is for the exhaust, and the outer pipe is for combustion air.

© CSIA 2013

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Direct Vent Advantages

• Obtains all combustion air from outdoors, making them an excellent choice for modern, tight homes. , g

• Highly spillage resistant – up to 25 pascals negative.

DV Installation Flexibility

• Short horizontal termination (through the wall).

• Vertical installations (through the ceiling).

Factory Built Chimneys

Factory built chimney can be used to vent many appliance types such as:

– Fireplaces.

– Wood/coal stoves.

– Gas logs.

•Tested to UL 103.

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Factory Built Chimney

• Three “general” types of factory built chimney are:– Air cooled.Air cooled.

– Air insulated.

– Mass insulated.

• Some designs utilize a combination of methods.

Air Cooled

• Sometimes called “thermosyphon”.

• Three separate walls create two air channels.

• Designed to circulate air through the channels.

• Continuous convection cools the flue gases.

• Originally intended for fireplaces.• Not recommended for “air-tight”

stoves.

Air Insulated

• Three walls spaced apart to create two separate channels of dead air.

• Dead air space is a relatively good insulator and helps keep the flue gases warm.

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Mass Insulated

• Stainless steel inner liner.• Outer liner generally stainless

but may be galvanized.• Has 1 to 2 inches of insulating g

material between the walls.• Insulation keeps the flue gases

warm.

Factory Built Fireplace Chimney – A Special Case

Included in UL 127 as part of the fireplace

Fireplace Chimney

• A factory-built fireplace chimney can only be used with the

ifi d l fspecific models of fireplaces with which they have been tested.

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Masonry Chimneys

Masonry chimneys, like factory built chimneys, can be used to vent many appliance types such as:

– Fireplaces

– Wood/coal stoves

– Gas logs

– Oil & gas appliances

Masonry Chimneys

Masonry chimneys can be built of;

– Brick.

– Block.

– Stone.

They are not tested or listed, but should be built according to local code.

Masonry Chimneys

• Modern masonry chimneys should be lined with a liner suitable for h lithe appliance.

• Liners can be:– Fireclay tile.

– Cast-in-place.

– Stainless.

– Aluminum. Vitreous tile liner

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Chimney Liners - 1777

• Chimney liners listed to UL 1777 can be used for all residential type appliances.

• This would include:This would include:– Solid fuel.

– Oil.

– Gas.

Chimney Liners - Oil

• Chimney liners tested to the temperature limits of UL 641 can only be used with appliances approved for use with L-vent or pp ppB-vent.

• This would include:– Some oil appliances

– Most gas appliances

Chimney Liners – Gas

• Chimneys liners tested to the temperature limits of UL 441 can only be used with gas appliances approved for B-vent. pp pp

• This would include:– Gas stoves

– Gas inserts

– Gas Furnaces or boilers

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What Does It Mean,The “House As a System”?

• The house as a system refers to how air moves in, out and

d haround a house.

• Air moves in and out of a house through the building envelope.

Building Envelope

The “building envelope” or “thermal envelope” of a house is made up of the surfaces thatis made up of the surfaces that enclose conditioned (heated or cooled) space.

Tighter Homes Have Caused Indoor Air Quality Problems

• Because homes are built tighter, there is less natural “air leakage” through the building g g genvelope. Less air movement allows pollutants to be trapped inside the house. Less air exchange also means less make up air available for combustion appliances.

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Why Is Indoor Air Quality an Issue?

• Studies show that Americans spend 80-90% of their time indoors.

• The number of people suffering from asthma and other respiratory diseases are on the rise.

• Homes are being constructed with tighter building envelopes.

• There is a legitimate concern about off-gassing from construction products.

Major Contaminants Affecting Indoor Air Quality

• Radon

• Formaldehyde

L d D t

• Carbon Dioxide (CO2)

• Carbon Monoxide • Lead Dust

• Soot - Particulates

• Tobacco Smoke

• Ozone

• Asbestos

(CO)• Nitrogen Dioxide

(NO2)• Sulfur Dioxide (SO2)• Biological

Contaminants

Regulations on Pollutants for Homes

• There are none!!!

• As of today, there are no enforceable codes or standards that outline what are acceptable levels of indoor air pollutants.

• Some organizations have developed guidelines for various pollutants.

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Chart of What Different Organizations Allow

Flue Sizing Requirements

• Good venting systems rely on properly sized flues.

• Many venting system problems are the result y g y pof improper sizing.

• Sizing recommendations can be found in manufacturers information or building codes.

Table ofContents

Masonry Fireplaces

• General “rule of thumb” says area of the fireplace flue should be at least 1/10th of the fireplace opening. p p g

• New requirements (NFPA & ICC)– Round flues should be 1/12th

– Square or rectangle should be 1/10th

– Rectangles greater than 2 to 1 aspect should be 1/8th

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Code Language

Round Square1/12th 1/10th

Rectangle1/10th

Long Rectangle1/8th

Factory Built Fireplaces

• Flue sizing for factory built fireplaces should be in accordance with the manufacturers installation instructions.

• Most factory built fireplaces use an 8” round flue, but some may be larger.

Fireplaces With Gas Logs

• Follow the gas log manufacturers’ directions for flue sizing.

• Many manufacturers will use NFPA 54Many manufacturers will use NFPA 54 (National Fuel Gas Code) recommendations based on BTU input and chimney height.

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Sample NFPA 54 TableHeight

of Flue(Ft)

Minimum Permanent Round Opening

8 in 13 in 20 in 29 in 39 in 51 in 64 inAppliance Input Rating (BTU X 1000)

( )

6 7.8 14 23.2 34 46.4 62.4 80

8 8.4 15.2 25.2 37 50.4 68 86

10 9 16.8 27.6 40.4 55.8 74.4 96.4

15 9.8 18.2 30.2 44.6 62.4 84 108

20 10.6 20.2 32.6 50.4 68.4 94 122.2

30 11.2 21.6 36.6 55.2 76.8 105.8 138.6

Solid Fuel Appliances

• Minimum area of the flue should be at least as large as appliance flue collar outlet.

• Maximum area of the flue should notMaximum area of the flue should not exceed three times the area of the appliance flue collar outlet for interior chimneys.

• For exterior chimneys it should not be more than twice the area.

Gas Hearth Appliances

• Flue sizing should be in accordance with the manufacturer’s recommendations.

• Generally they will range from 3” to 8”Generally they will range from 3 to 8 .

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Chimney or Vent Location

• The location of the venting system will have a dramatic effect on appliance performance.

• Favorable locations can be assured byFavorable locations can be assured by thorough planning during the design of the home and appliance choice.

Table ofContents

Interior Venting Systems

• Interior systems are surrounded by warm air.

• Interior systems will always perform better than outdoor systems.

Interior Venting Systems

• Promote fast, easy start-up.

• Maintain better draft.

• Reduce condensation & creosote• Reduce condensation & creosote.

• Rarely have “smoky tail-out.”

• Radiate heat from the chimney indoors, not to the outside.

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• Exterior systems are surrounded by cold air.

Exterior Venting Systems

• Exterior systems will always perform less favorably than interior systems.

• Promote “cold-hearth syndrome.”

• Make it hard to establish fire.

• Promote condensation of flue gases and

Exterior Venting Systems

• Promote condensation of flue gases and increased creosote.

• Have lower draft because there is less temperature differential.

Cold Hearth Syndrome

• “Cold hearth syndrome” occurs when cold outside air flows down a chimney that is not currently in use.y

• Common causes are:– Exterior chimney serving appliance located

below the NPP.

– Building envelope higher than chimney.

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Higher Than Heated Area

• Whether located indoors or out, the chimney should

i hi h hterminate higher than any portion of the heated area (building envelope).Heated

Area

Chimney Termination

All residential chimneys must terminate at least 36” above the point they pass through the roof and 24” above any structure within 10 feet of the chimney.

The 3-2-10 Rule

Chimney Termination• Here’s one for the record books!

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Vent Termination

• B-vents with listed caps shall terminate in accordance with

fmanufacturers installation instructions or NFPA 54.

Pressure

• Reference – (WRT)

• Neutral

• Negativeg

• Positive

• Measurement

Table ofContents

Reference Pressure

• Pressure is a force that causes bodies to react; pressure can be natural or mechanical.

• When measuring pressure we must have aWhen measuring pressure, we must have a reference point. (WRT= with respect to)

• In the hearth industry we usually measure pressure in reference to the outdoors but may also measure with respect to other areas of the building.

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Neutral Pressure

• Neutral pressure occurs when there is no air flow between h “ f ” d h

No Airthe “reference” and the measured area.

No Air Movement

Positive Pressure

• The building is under positive pressure when the air flow moves from the

dmeasured pressure area (indoors) to the reference pressure area (outdoors).

Air Flow

Negative Pressure

• The building is under negative pressure when air moves from the reference

( d ) hpressure (outdoors) to the measured pressure area (indoors). Air Flow

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Pressure Measurement

• Pressure is commonly measured in one of the following units:– PSI (pounds per square inch)PSI (pounds per square inch)

– In wc (inches of water column)

– Pascals

PSI

• PSI (Pounds per Square Inch) is a standard measure of pressure in th U S b t h littlthe U.S. but has little value in the hearth industry.

IN.WC.

• In wc (Inches of Water Column) is used in the hearth industry to

d f dmeasure draft and gas pressure.

• 1 PSI = 27.71 inches WC

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Pascals

• Pascals are very small units of pressure and are ideal for measuring i fl i b ildiairflow in buildings.

• 1 PSI = 6895 pa.

• 1” In wc = 248.9 pa.

Draft & Flow

• Draft and flow work together in successful venting designs.

Table ofContents

Venting System Purpose

• All atmospherically vented appliances are dependent on a properly operating chimney (or vent) for two important functions;) p ;

– Exhaust the products of combustion safely to the outside atmosphere.

– Draw oxygen into the appliance to sustain combustion.

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Vent System Size

• Of the three factors influencing flow, the size (area) of the venting system passageways has the greatest affect.p g y g

• Formula for figuring cross-sectional area of square or rectangle is area = L X W.

• Formula for figuring cross-sectional area of a round flue is area = pi X R2.

Measuring Draft

• Chimney draft is measured in inches of water column.

• Good draft will be represented by a negative p y gnumber because the pressure in the chimney is less than the surrounding atmosphere.

• Lower negative numbers represent greater draft. • -.1 is greater draft than -.01.

Fireplace Vs. Closed Heaters

• Fireplace performance problems are more commonly caused by inadequate flow.

• Problems with closed heaters are most oftenProblems with closed heaters are most often related to poor draft.

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Combustion Air

• All fuel-burning appliances need an ample supply of combustion air to operate well.

Table ofContents

Obvious Problems

Combustion air supplies should be permanently open.

Combustion air supply

p

Do not allow the homeowner to close them off because they are “getting cold air in the house”.

Complete Combustion

Needs:

• Oxygen

• Fuel

Avoids:

• Insufficient air

• Inadequate venting

• Heat • Flame impingement

• Contaminated air

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Air Content

OxygenNitrogenOther• 78 % Nitrogen

• 21 % Oxygen• 1 % Other

Perfect Combustion (Gas)

HEAT

N2

AIR

O2

CH4

CO2

H2O

N2

Excess Air Combustion

15 cu.ft. f Ai

HEATof Air

1 cu.ft. of Gas

12 cu.ft. of Nitrogen

1 cu.ft. carbon dioxide

2 cu.ft. water vapor

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Dilution Air

• So we see that 15 cubic feet of air is required for each cubic foot of natural gas burned.

• However draft hood equipped appliancesHowever, draft hood equipped appliances require about twice this much air due to the effects of dilution air - the air drawn through the draft hood.

Combustion Gas Volume

Approximately 30 cu.ft. of total flue gas

15 cu. ft. primary combustion air

15 cu.ft. dilution air into draft hood

for each cubic foot of natural gas burned

Other Hydrocarbon Fuels

• The combustion air examples shown were for natural gas, however all hydrocarbon fuels require approximately 1 cubic foot of q pp ycombustion air for each 100 BTU’s of heat produced.

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Summary

• The building must have adequate combustion air.

• The venting system must be able to removeThe venting system must be able to remove the flue products safely to the outdoors.

Air Flow Through Openings

• Air flow through ducts, vents or holes is determined by the size f th i d thof the opening and the

pressure difference across the opening.

+ + - -

Table ofContents

Air Flow Through Openings (Approximate)

Opening Size

Pressure Differential (Pa)

2 4 6 8 10 12Air Flow in CFM

5 i 7 6 10 7 13 1 15 1 16 9 18 55 sq.in. 7.6 10.7 13.1 15.1 16.9 18.5

7 sq.in. 10.6 15.0 18.4 21.2 23.7 26.0

10 sq.in. 15.1 21.4 26.2 30.3 33.8 37.1

15 sq.in. 22.7 32.1 39.3 45.4 50.8 55.6

20 sq.in. 30.3 42.8 52.4 60.5 67.7 74.1

25 sq.in. 37.8 53.5 65.5 75.7 84.6 92.7

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Airflow Through Openings (Formula)

1. The preceding table was developed using a formula for airflow through orifices and does not account for restrictions due to weatherhoods, screens, elbows and ducting.

2. The formula is CFM = 1.07 X A (area of opening in square inches) X square root of pressure drop (measured in pa).

Exhaust Air Flow

Average exhaust air flow for common appliances;

•Oil or gas furnace – 50 CFM

•Open fireplace 250 CFM& up•Open fireplace – 250 CFM& up

•Fireplace with doors – 100 CFM

•Woodstove – 25 CFM

Air Supply for Fireplace

2015 IRC Requirements:

• Minimum 6 sq.in. opening

• Maximum 55 sq in opening• Maximum 55 sq.in. opening

• Permitted in the fireplace, or within 24 inches of FP opening.

• Must supply all combustion air from outdoors ?

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Passive Air Supply

• Can supply some of the combustion air needed for the fireplace.

• Can reduce the level of negative pressure in the area.

Atmospheric Effects

• Passive combustion air openings respond to natural pressure differences.

• If the pressure indoors is lower thanIf the pressure indoors is lower than outdoors, air will flow in.

• If the pressure outdoors is lower, air will flow out.

Wind Effects

Wind

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Air Flow in Buildings

• Air flows from areas of high pressure to areas of low pressure.

• Air flow out is equal to air flow in knownAir flow out is equal to air flow in, known scientifically as conservation of mass.

• Air movement requires a driving force.

Table ofContents

Driving Forces

Building pressure is effected by:• Natural causes

– Stack effect– Wind

• Mechanical causes– Fans (exhaust) – dryers, ranges, bathroom, whole house,

central vacuum– Heating system air handler

• Venting systems– Mechanical – Natural or atmospheric

Stack Effect

• Air flows toward the top of the building because “warm air rises” in other words; it is lighter than the surrounding air.g g

• Stack effect increases as the indoor/outdoor temperature difference increases.

• Stack effect increases as the building height increases.

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Stack Effect (Winter)

P i hi h t

+ + + +

- - - - -

Pressure is higher at the top and air flows out, lower at the bottom and air flows in.

Stack Contributors

• Any opening (leak) at the top of the building that lets air escape will

ib h kcontribute to the stack effect.– Recessed lights.

– Attic hatches.

– Skylights.

Wind Effect

High

Wind

High Pressure Low

Pressure

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Wind Effect on Building Openings

• Openings on the windward (high pressure) side of the building will allow air to enter the building.g

• Openings on the leeward (low pressure) side of the building will allow air to escape the building.

In & Out

Wind

Fan Effect

• Any mechanical exhaust system that removes air from the building can cause b ildi d i ibuilding depressurization.

• The effect on atmospheric appliances can be dramatic.

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More Fans

• Whole house fan

• Range hood

• Central vacuum

• Clothes dryer

• Bathroom fans

• Remember, air in must equal air out !

Powered Attic Exhaust

• When the attic is not properly ventilated, powered exhausters can

ib b ildicontribute to building depressurization by drawing air from the conditioned space.

Attic Ventilation

• Without adequate soffit or gable vents, powered exhausters may pull air from h b ildi h hthe building through any

opening or leak between the attic and indoors.

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Air Flow by Fans

Fan Type Exhaust (CFM)

Bath Fan 25 – 75

Range Hood 75 – 125

Downdraft Range 200 – 400 +

Whole House Fan 300 - 500

Central Vac 50 – 100

Clothes Dryer 75 – 150 250

Duct System Problems

• HVAC ductwork can have a tremendous effect on building air flow patterns.

• These effects are caused by:These effects are caused by:– Imbalanced duct design.

– Duct leakage.

– Duct outlet isolation.

Furnace Airflow

• The furnace blower causes air to flow through the ductwork.– Return ducting under

negative pressure.

– Supply ducting under positive pressure.

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Typical Ductwork Layout

Balanced System

• In a well designed HVAC system the return flow out of the living space equals the

l fl b k isupply flow back in.

• This is by definition a balanced system.

Duct Leakage

• 15 – 20 percent duct leakage is not uncommon.

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Imbalanced System

• Occurs when return and supply flow is not equal.

• The most common scenario is for the return volume to exceed supply.

• Appliances in living area are then likely to spill because of the negative pressure created.

Return Less Than Supply

• When return out is less than supply in, the living area is pressurized.

• Appliances in living area work well.

• Appliances in basement spill.

Outlet Isolation

• In systems with a central or common return, depressurization of the living area can occur as a result of;;– Closed doors.

– Blocked supply vents.

– Duct zoning.

• A room with a closed door can pressurize 10 to 20 pa (supply side = positive).

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Vent Systems

• Both mechanical and naturally vented appliances can cause area depressurization.

• In a contest mechanical systems usuallyIn a contest, mechanical systems usually win!

• Adequate combustion air is the answer.

Solid-fuel Exhaust Fan

• Conventional fireplaces with hot fires can exhaust over 250 CFM.

• Think of the fireplace as a solid-fuel fired exhaust fan.

Locating the NPP

• Locate the NPP with a gauge that reads accurately in Pascals.

• Operate appliances in their “normal” mode for the specific test condition.

Table ofContents

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High Planes

+ + + +

• The NPP could be at the top of the “envelope” of the building.

• This is not uncommon in d t ti + + + +

- - - - -

modern construction.

• Entire living area negative with respect to the outdoors.

- - - - -

Testing

• Procedure for testing house pressures.

© CSIA 2013

Venting Problems

• Spillage

• Backdrafting

• Flow reversal• Flow reversal

• Wind induced downdraft

• Inadequate flow

Table ofContents

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Spillage

• Spillage occurs when some of the combustion gases enter the building.

• With spillage, some upward flow continues.

Backdrafting

• Backdrafting occurs when the chimney flow is completely reversed and all of the combustion gases enter the building.

Causes

• Spillage and backdrafting can be caused by a variety of conditions but generally fall into one of the following three categories;– Wind induced Downdrafting.

– Flow reversal.

– Inadequate flow.

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Some Are Obvious

Nuisance!

• Minor or occasional spillage may not be life threatening but should not be tolerated.– Damages home.

– Prevents full enjoyment.

Dangerous!

• Spillage and backdrafting can be dangerous!

• Noxious smoke and CO (Carbon Monoxide) can enter the building.

• Can be life threatening if not corrected.

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Wind Induced Downdraft

WIND

Wind Induced Downdraft

• The previous slide showed a “classic” wind-induced problem.

• Proper termination height is a good startProper termination height is a good start, but isn’t always enough…..

11

Wind

11 ft.1111 ft.

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Solutions for Wind Induced Downdrafts

• Chimney caps.– Standard caps.

– Venturi caps.Venturi caps.

• Extend the chimney above the zone of turbulence.

• Remove the barrier, if possible.– Trees.

• Burn only on favorable days.

Caps Can Help !

• Standard caps may deflect wind enough to allowenough to allow the chimney to function correctly.

Caps Can Help !

• Some caps are designed to take advantage of the wind

d t ll iand actually improve chimney performance.

The high cost of extending a chimney justifies using chimney caps as a trial solution.

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Flow Reversal

• Flow reversals are caused by unusually low pressure at the appliance or fireplace.

• Low pressure pulls air (and flue gases)Low pressure pulls air (and flue gases) down through the venting system.

• May be caused by wind, stack or mechanical effect.

Causes of Flow Reversal

• Stack effect

• Other chimneys

• Mechanical effects• Mechanical effects– Exhaust fans

– Air handlers

• Wind loading

Stack Effect

• The normal air infiltration pattern of a house can create a t k ff t dstack effect and

reverse chimney draft.

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Flow Reversal From Chimney

• When two flues share the same chimney, smoke can be

i l t d d t lFire in

recirculated due to low pressure around the downstairs fireplace or appliance.

Upstairs FP

Smoke out Downstairs

Smoke

Solution!

• Bringing air in low in the building is probably the most effective solution.

Fire in• Feed the air into the

negative pressure zone.

• Lowers NPP.

Fire in Upstairs FP

Smoke out Downstairs

Smoke

Correcting Flow Reversals

• Most flow reversals can be corrected by repairing / stopping leaks or providing outside combustion (or make-up) air to theoutside combustion (or make up) air to the appliance causing the reversal.

• In extreme cases, it may be necessary to use a mechanical draft inducer.

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Forced Draft

• Forced draft is created by a mechanical fan pushing flue gases through the venting

i i d hsystem – it is mounted at the inlet (or midstream) of the venting system and creates positive pressure in the vent.

Fan

Forced Draft

• Forced draft is not recommended because most venting systems g yare not designed to have positive pressure inside the system.

• Potential hazard if flue gases escape.

Fan

Induced Draft

• Induced draft is created by a mechanical fan drawingflue gases through the

Fan

g gventing system – it is mounted at the outlet of the venting system and maintains negative pressure in the vent.

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Draft Inducer

Draft Inducer Rules

• Ever since the 2000 edition of NFPA 211, rules exist for mechanical exhaust systems used with manually fired appliances;– Must have visible and audible warning g

system (with battery back-up) to detect failure or loss of power.

– Must install Smoke and CO detectors (with battery back-up).

– Must maintain level of draft recommended by appliance manufacturer.

Inadequate Flow

• Inadequate flow occurs when the venting system does not have sufficient capacity to remove all flue products.p

• Generally caused by poor draft or insufficient flow capacity.

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Flow Distracters

• Outside chimney

• Undersized chimney

• Oversized chimney

• Short chimneys

• Heat reclaimers

• Blockages• Oversized chimney

• Long laterals

• Too many elbows

• Oversized appliance

g

• Obstructions

• Excessive buildup

• Poor burning habits

• Airtight homes

Reduction of Flow Capacity

• Creosote & soot buildup reduce the flow capacity of the venting.

• The effect is more significant in smaller gflues than in larger flues.

8” FlueNo Buildup

The effective area is 50.24 square inches

The effective area is 28.26 square inches, a reduction of 44%

1 inch of buildup reduces flue diameter by 2”

8” Flue1” Buildup

Diagnostic Testing

• Procedures and equipment

Table ofContents

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Step by Step

• Gather information.

• Tentative diagnosis.

• Recommend a solution• Recommend a solution.

• Test your solution.

Appliance Spillage Worksheet

Gathering Information

• Gather info through personal observation and customer interview.

• Questions for the interview:

1. Is the problem constant or intermittent?

2. Is the problem gradually getting worse?

3. Under what circumstances does it occur (wind, temperature, start-up, tail-out, etc.)?

4. What solutions have been tried, and what were the results?

Duplicate the Problem

• Duplicate the problem as closely as possible.

• Observe.

• Test• Test.

• Experiment.

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Recommend a Solution

• Based on observations and collected data.

• Give consideration to cost in your recommendationrecommendation.

• Ideally you can propose multiple options and let them choose.

Test Your Solution

• Whenever possible, test your solution before actual installation.

• Performance problems can be mystical andPerformance problems can be mystical and difficult to identify.

Inspect the System

• Check out the system.

• Identify any problems.p

• How do they relate to the problem described?

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Inspect the System

• Many problems will stare you in the face and others will elude

b ffyour best efforts at detection.

• This clogged cap screen was responsible for smoking up a house.

Inspect the System

• This damaged vent was causing appliance spillage.

Inspect

• Inspections must be thorough.

• Poorly performing systems often suffer from a combination of small problems rather than one single problem.

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Measure Area Pressure

• Both with appliances off and with appliances operating.

Measure Area Pressure

• Stick manometer probe out of window or

d dunder doorway.

• Seal around openings.

Depressurization Limits

• Some appliances are more resistant to spillage than others.

• Depressurization limits set a safe level thatDepressurization limits set a safe level that various appliance types should be able to tolerate.

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Depressurization Limits

Appliance Type Depressurization Level (pascals)

Open systems 5Open systems 5

Closed systems 5 - 10

Woodstoves 5 - 7

Direct Vent 10 - 20

House Depressurization

• House depressurization varies with the tightness of the house.

• A Canadian study showed a range of 64 to 717A Canadian study showed a range of 64 to 717 CFM of airflow required to depressurize an average home to –5 pa.

• Average in that test was 233 CFM required to reach –5 pa.

Check Air Flow

• This pictures shows airflow into the home as a

l f iresult of negative pressure.

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Check Flow

• For fireplaces, a simple flow test can be conducted with toilet itissue or newspaper

strips.

• USE CAUTION when using this method with burning appliances!

Check Flow

• For appliances w/ draft hoods, a smoke match works well.

Smoke Puffers

• A smoke puffer is very useful for visualizing airflow.

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Measure Carbon Monoxide

• Measuring CO is useful to uncover undetectedundetected spillage and equipment malfunction.

CO Protocol

• Review the worksheet.

Measuring CO

• Short term.

– “Spot” readings.

– Identifies current problems.p

• Long term.

– Data-logging.

– Data-logging gives you a long term picture of real life conditions.

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Operate & Observe

• Operate the troubled appliance and observe how it f ifunctions.

• Make note of any problems.

• Can be time-consuming.

Operate “Naturally”

• During diagnostic testing, appliances must be operated in their normal

dmode.

• Appliances in closets must be operated with door closed.

Experiment

• Operate other appliances.

• Open and closeOpen and close windows and doors.

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Diagnostic Procedure

Is There A Ghost In The House ?

• Fireplaces and other hearth appliances are often blamed for “mysterious” sooting that has y gnothing to do with the hearth.

• These “mystery” soot problems can be difficult to diagnose.

Table ofContents

A Source and A Force

Source

• Carbon soot

Hearth appliances

Force

• A force is required to d it th t i l– Hearth appliances

– Heating appliances

– Candles

– Cooking

– Smoking

– Auto exhaust

• Dirt and dust

deposit the material.

– Impaction

– Gravity

– Attraction

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Gravity Staining

Impaction Staining

The Candle Culprit

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Diagnosing the Problem

• Sooting information.

Ventilation

• Ventilation of homes is important, especially as homes are made more air-tight.

• Ventilation removes:

Table ofContents

– Moisture.– Air-borne pollutants.– Odors.

• Ventilation provides fresh air.

I considered fresh air as an enemy and closed with extreme care every crack and crevice in the room I inhabited.

Experience has convinced me of my p yerror. I am certain that no air is so unwholesome as the air in a closed room that has been often breathed and not changed.

Benjamin Franklin

18th Century

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I considered fresh air as an enemy and closed with extreme care every crack and crevice in the room I inhabited.

Experience has convinced me of my p yerror. I am certain that no air is so unwholesome as the air in a closed room that has been often breathed and not changed.

To have pure air, your house must be so constructed as that the outer atmosphere shall find its way with ease to every corner of it. House architects hardly ever consider this.

As it is, they built what pays best. And there are always people foolish enough to take the houses they build. And if in the course of time, the families die off, as is so often the case, nobody ever thinks of blaming anything but , y g y gProvidence for the result.

Ill-informed medical men aid in sustaining the delusion, by laying the blame on "current contagions".

Once insured that the air in a house is stagnant, sickness is certain to follow.

-Florence Nightingale, 1859

To have pure air, your house must be so constructed as that the outer atmosphere shall find its way with ease to every corner of it. House architects hardly ever consider this.

As it is, they built what pays best. And there are always people foolish enough to take the houses they build. And if in the course of time, the families die off, as is so often the case, nobody ever thinks of blaming anything but , y g y gProvidence for the result.

Ill-informed medical men aid in sustaining the delusion, by laying the blame on "current contagions".

Once insured that the air in a house is stagnant, sickness is certain to follow.

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Need for Ventilation

• The need for ventilation is indicated by:– Lingering odors

– Condensation on windowsCondensation on windows

– Interior moisture damage

– Mold & mildew

Ventilation Strategies

• Exhaust only

• Supply only

• Balanced• Balanced

• Balanced with heat recovery (HRV)

Exhaust Only

• Advantages

– Least expensive

• Disadvantages

– May backdraft appliancesappliances

– Unable to control source of incoming air

– Unable to filter incoming air

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Supply Only

• Advantages.

– Able to select source of

• Disadvantages.

– May drive moisture intosource of

incoming air.

– Able to filter incoming air.

– Aids in appliance venting.

moisture into walls cavities where it could condense.

Balanced System

• Advantages.

– Maintains balanced

• Disadvantages.

– Most expensive.balanced (neutral) pressure.

– Can be coupled with heat recovery.

System Qualities

• Well designed ventilation systems should be “transparent” to the building occupants;– QuietQ– Draft-free– Low maintenance– Require little, if any, user control– Low operating cost

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Recommended Ventilation

• ASHRAE recommends 0.35 ACH.

• Most building codes base ventilation i t t l d drequirements on occupant load and use.

• Need to consider the source of pollution – is it the building or the people ?

Ventilation Rates

• The rates shown are per person.– Living areas in house = 15 CFM.– Kitchens = 100 CFM (I) or 25 CFM (C).– Bathrooms = 50 CFM (I) or 25 CFM (C).– Office areas = 20 CFM.– Restaurants = 20 CFM.– Bars = 30 CFM.– Smoking lounges = 60 CFM.

Make-up Air

• Strategies.

© CSIA 2013

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Blower Door

• A blower door is used to determine house “leakage”.g

Table ofContents

Blower Door Testing

• The blower is operated to depressurize the house to –50 pascals, while measuring airflow.

• This value is called the CFM50 as in 1500 50CFM50.

• 1500 CFM50 would indicate that there is 1500 CFM of air flowing through the house when it was depressurized to –50 pa.

Blower Door Data

• 100 CFM50 would indicate a very tight house, while 5000 CFM50 would indicate a very leaky houseindicate a very leaky house.

• 1500 – 2000 CFM50 is normal.

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CFMNatural

• To convert CFM50 to CFMNatural simply divide by 20.

1500 CFM 75 CFM• 1500 CFM50 = 75 CFMNatural.

Air Changes Per Hour

• To convert CFM50 to ACH, multiply CFM50 by 60, and then divide by the volume of the housevolume of the house.

• This will give you ACH50, which you divide by 20 to get ACHNatural.

ACH

• CFM50 = 2000 in a 1500 square foot house.

• 1500 ft2 = 12,000 ft3

• 2000 X 60 (minutes) = 120,000

• 120,000 / 12,000 (cubic foot) = 10

• 10 / 20 = 0.5 ACH

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Questions ???