Zonal Pressure DiagnosticsWhere is the pressure boundary?

Bill Van der Meer

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Zonal Pressure DiagnosticsAs a result of this presentation participants

will:• Understand the relationship between thermal and air

barrier of a home• Be introduced to the basics of zonal pressure diagnostics

and interpretation of results• Become aware of the value of applying to zonal pressure

diagnostics in the field

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Zonal Pressure Diagnostics

• Overview of Pressure Diagnostics• Air Barriers and Thermal Boundaries• How to Do Zonal Pressure Testing• Applied Zonal Testing

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Overview of Pressure Diagnostics

Overview of Pressure Diagnostics

• Pressure diagnostics help determine:– How leaky a house is– Pressure boundary of a house– Communication by air leakage

between zones inside the building shell

– Presence of duct leakage (pressure pan testing)

– Dominant duct leakage – Room pressure imbalances

(pressure balancing a forced airdistribution system)

– Worst-case depressurization othe Combustion Appliance Zone

– Worst-case draft of combustion appliances

f

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Types of Pressure Diagnostics

Tests commonly performed in a house depressurized by a blower door:

– Blower door test– Zonal pressure Diagnostics– Pressure pan testing

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Types of Pressure Diagnostics

Introduction to Zonal Pressure Diagnostics

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“Doing Zonals” to leak test air barriers

Attic with reference to house

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Air Barrier

Insulation

The Air Barrier and Thermal Boundary must be together and continuous.

Air Barriers and Thermal Boundaries

Tests commonly performed under normal operating conditions (using existing air handler and exhaust fans):

– Combustion appliance zone pressure

– Dominant duct leakage– Worst-case draft

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The building will be difficult to heat and cool if the boundaries are misaligned or if there are holes, voids or gaps.

Air Barriers and Thermal Boundaries

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Locating the Thermal Boundary

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Just Where Is the “Air Barrier”?

How to Do Zonal Pressure Testing13

ZPD How To

Measuring Zonal Pressures

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With the Blower Door at -50 Pascals, we can measure the pressure difference between different zones inside the building enclosure.

A “zone” is any area that can be closed off.

What Do We Measure?

• Not total pressure, but pressure differences between one space and another

• Always one space with reference to (WRT) another– House WRT outside– Attic WRT house– Porch roof cavity WRT

outside

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Dual Channel Display

Controls

Dual Channel Input Ports

Dual Channel Reference Ports

Manometer Setup for Zonal Testing

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Channel A Channel B

-50

House WRT Outside

0-50

Connect a hose from the reference port to the outside (channel A).

Input port on Channel A is left open to the inside. Hose to outsideChannel B is unused.

Manometer Setup for Zonal Testing

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Channel A Channel B

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House WRT Zone

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Attic WRT House

Hose to zone

Connect a hose from the input port to the zone (channel B).Reference port on channel B is left open to the inside.Channel A is unused.

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Verifying Zonals

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Attic WRT House

Attic WRT House

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Attic WRT Outside

Attic WRTOutside

-12

20

21

48

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20

10

The attic WRT to outside measurement confirms the attic WRT house measurement because their absolute values add up to 50 Pascals.

Applied Zone Pressure Testing

Leak Testing Air Barriers, Simulation

Are the zones mostly inside or outside?

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Outside Zones and Inside Zones

Unheated zones outside the house should be closer to 50 Pascals.

Outside Zones(Unheated)

AtticsGaragePorches (sometimes)CrawlspaceBasement (sometimes)

Heated zones inside the house should be closer to 0 Pascals.

Inside Zones(Heated)

Interior wallsFloors between storiesPorches (sometimes)CrawlspaceBasement (sometimes)

Testing Inside Zones(Manometer Indoors)

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-50 pa.

Bedroom with air leak to attic

Question is:Is the bedroom zone mostly outside or mostly inside?

• House WRT outside = -50 Pascals• Bedroom WRT house = 20 Pascals• Seal leaks from bedroom to attic.• Readjust blower door to -50 Pascals.• Retest bedroom WRT house.• Goal is to bring bedroom closer to inside, which means the zone WRT house is closer to 0 Pascals.

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Zone Connections (Manometer Outdoors)

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Porch roof cavity is open to exterior wall cavities

The goal is for the zone WRToutdoors to be close to “0”Pascals.

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Triple Decke

-50

A Typical Turn-of-the-Century r

pa.

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Two-story balloon-framed with one-story addition and unheated porch over unheated basement

Leaky connection to wall cavity

Unsealed/Uninsulated

50

0

Air Sealed

-

An Effective Air Barrier, Defined

50 pa.

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Two-story balloon-framed with one-story addition and unheated porch over unheated basement

Air Sealed/Uninsulated

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An Effective Thermal Boundary

-50 pa.

Two-story balloon-framed with one-story addition and unheated porch over unheated basement

Insulated/Air Sealed

One-and-a-Half Story Cape

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30

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Collar beam attic

Rafter bays

Kneewall attic

-50 pa.Heated living space

Heated bedroom

Heated basement

Uninsulated/Unsealed

One-and-a-Half Story Cape

0

-50 pa.

50Insulated/Air Sealed

Enclosed Porch Strategies

Heatedporch

0

-50 pa.

Heated basement

Main house

Bring it in?

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Enclosed Porch Strategies

Unheatedporch

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-50 pa.

Heated basement

Main house

Or leave it out?

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Kitchen soffit and base cabinet open to a

vented attic

Test Key Areas

• Dropped soffits• Attics, side attics, porch

roofs• Garages, basements,

crawlspaces• Chases (plumbing, electric,

duct, chimney)• Plumbing access, panned

returns, etc.

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Where there’s a problem,

there’s usually a solution.

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Conclusions Do “Zonals” to Make Useful Decisions

• Decide what’s inside and what’s outside.• Determine Air Barrier & Thermal Boundaries.• Decide where the Air Barrier & Thermal

Boundary should be.• Determine the duct location (inside or

outside) & where ducts should be.• Determine if the Air Barrier and Thermal

Boundary line up.

Conclusions Keep It Simple!

• Record basic pressure measurements.

• Verify unusual readings by measuring the zone WRT outside.

• These tests should take very little time.

• Verify readings through visual inspection.

• Are the zones where they are supposed to be?

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WAPTAChttp://lowincomewx.org/online_training/

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