MakeMake‐‐Up Air for ResidentialUp Air for ResidentialMakeMake‐‐Up Air for Residential Up Air for Residential Kitchen ExhaustKitchen Exhaust

Designing and Installing forDesigning and Installing forDesigning and Installing for Designing and Installing for Code ComplianceCode Compliance

What We’ll CoverWhat We’ll CoverWhat We ll CoverWhat We ll Cover

• Background• Code requirementsCode requirements• Gravity dampers• Installation options• Design and live demoDesign and live demo

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What is MakeWhat is Make up Air (MUA)?up Air (MUA)?What is MakeWhat is Make‐‐up Air (MUA)?up Air (MUA)?

Makeup air: Outdoor air and transfer air used to replace exhaust airused to replace exhaust air

Outdoor air: Air that enters a building gthrough a ventilation system, through intentional openings or by infiltrationintentional openings … or by infiltration.

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How does MUA Flow into the Dwelling?How does MUA Flow into the Dwelling?How does MUA Flow into the Dwelling?How does MUA Flow into the Dwelling?

Intentional  Existing cracks or openings (i.e., an outdoor air duct ith d )

gaps in the building envelope

with a damper)

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How does MUA Flow into the Dwelling?How does MUA Flow into the Dwelling?How does MUA Flow into the Dwelling?How does MUA Flow into the Dwelling?

Intentional  Existing cracks or openings (i.e., an outdoor air duct ith d )

gaps in the building envelope

with a damper)

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Provide MUA ToProvide MUA ToProvide MUA To…Provide MUA To…

Meet code requirementsq

M i i d i d i li b idiMaintain good indoor air quality by avoiding excessive depressurization during operation of exhaust appliancesof exhaust appliances

Enable exhaust hood to function as designed

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Max Recommended DepressurizationMax Recommended DepressurizationMax Recommended DepressurizationMax Recommended Depressurization

5 15 50

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MUA CodeMUA Code RequirementsRequirementsMUA Code MUA Code RequirementsRequirements

  

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MUA CodeMUA Code RequirementsRequirementsMUA Code MUA Code RequirementsRequirements

• When: Exhaust rate > 400 cfm• HowMuch: “approximately equal to exhaust”How Much:  approximately equal to exhaust• Include: “a means of closure automatically 

ll d d i l lcontrolled to start and operate simultaneously with the exhaust system”

IRC: 2009 and 2012 Section M1503 4IRC: 2009 and 2012 Section M1503.4IMC: 2009 and 2012 Section 505.2

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Gravity Dampers: Why Not?Gravity Dampers: Why Not?Gravity Dampers: Why Not?Gravity Dampers: Why Not?

N t d b d• Not approved by code • Are not “automatically controlled” per IRC M1503 4M1503.4

M l diff i l• May not open at low pressure differentials

• May not address back‐drafting issue

• Specify motorized makeup air damper at a minimum

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Gravity DampersGravity DampersGravity DampersGravity Dampers

Contractor‐made gravity damper, actual install in 2000.  Notice the canvas hinge (below) attached with rivets (left).

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Gravity DampersGravity DampersGravity DampersGravity Dampers

• IRC  2015 Public Comment Hearings

• Atlantic City, NJ: Oct 3‐8, 2013

• Registered Code Officials can Vote!Registered Code Officials can Vote!• Disapprove  RM34 (gravity dampers) • Approve RM31 or RM35 (motorized dampers)

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MUA Is Recommended ForMUA Is Recommended ForMUA Is Recommended For…MUA Is Recommended For…

Large range hoods (those

Newer energy efficient “tight”

Dwellings with indoor naturalhoods (those 

over 300 cfm)efficient,  tight  

or “green” dwellings that are well air

indoor natural draft combustion 

appliancesare well air‐

sealed

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INSTALLATION CONFIGURATIONS

Installation Option 1Installation Option 1Installation Option 1Installation Option 1

1. Interlock t l f ithcentral fan with MUADMUAD  

Hood On

MUAD Open

Central Fan On

Permitted by IRC Section M1602.1

Make‐Up Air for Domestic Range Hood Exhaust

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15

Installation Option 2Installation Option 2Installation Option 2Installation Option 2

2. No interlock between MUAD and central fanand central fan  

Hood On

MUAD Open

Permitted by IRC Section M1602.1

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Installation Option 3Installation Option 3Installation Option 3Installation Option 3

3 Routed to3. Routed to interior registerg

Hood On

MUAD Open

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Installation Option OverviewInstallation Option OverviewInstallation Option OverviewInstallation Option Overview

System Code Compliant? Tempers MUA Circulates MUA

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Outdoor Air Intake LocationOutdoor Air Intake LocationOutdoor Air Intake LocationOutdoor Air Intake Location

¼” – ½” screen: IRC 303.6

Minimum 1 foot and clear of snow and debris: IRC 303.5

MUA ducts should not draw air from crawlspaces, garages, attics, adjacent dwelling units, or any enclosed part of the building: IRC 303.5.2

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MAKE‐UP AIR THEORY

ConsiderationsConsiderations C b tiConsiderationsConsiderations Combustion Appliance Types

MUA  Air Tightness Kitchen Exhaust Rate

Solution of DwellingExhaust Rate (Actual)

Damper Installation 

Configuration

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Governing EquationsGoverning EquationsGoverning EquationsGoverning Equations

Darcy‐Weisbach 212

VCfLp

H l d

1097

CD

p

2 Haaland 211.1

Re9.6

7.3log8.1

Df

ASHRAE Fundamentals

np

r

rrr p

pQQ

1,

2,1,2,

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DESIGN

Using Broan/BEST’s MUA Specifier ToolUsing Broan/BEST’s MUA Specifier ToolUsing Broan/BEST s MUA Specifier ToolUsing Broan/BEST s MUA Specifier Tool

St t l l d Cli t

Outputs supplied by the Range Hood MUAOutputs supplied by the Range Hood MUA SpecifierSpecifier include…include…

State level code requirements

Climate considerations

Design exhaust rate

Dwelling leakage at design 

d i tidepressurization

Flow throughFlow through automatic MUA 

dampers

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Broan/BEST MUA Specifier Tool Broan/BEST MUA Specifier Tool DemonstrationDemonstration

Access via Access via Internet: Internet: www.broan.comSelect: “Specifier Tools” from top toolbarSelect: “Specifier Tools” from top toolbar

Select: “MakeSelect: “Make‐‐Up Air Damper Tool” from left toolbarUp Air Damper Tool” from left toolbar

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Q & AQ & AQ & AQ & A

Need BPI or AIA credits? Contact: sbowles@newportventures netContact: sbowles@newportventures.net

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Bonus Bonus Slides: Slides: NNot Included in Original Webinarot Included in Original Webinar

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Climate ConsiderationsClimate ConsiderationsClimate  ConsiderationsClimate  Considerations

Cold If integrating with a furnaceCold climate zones

If integrating with a furnace, pre‐heating the outdoor MUA may be necessary.

Humid Wh h d lli i i liHumid climates

When the dwelling is in cooling mode, operation of the AC and/or a supplementary dehumidification system shoulddehumidification system should be considered.

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Limits to MUA in Furnace Return DuctLimits to MUA in Furnace Return DuctLimits to MUA in Furnace Return DuctLimits to MUA in Furnace Return Duct

Climate Zone

MaxRecommended OA Flow

as % of Total FurnaceZone as % of Total Furnace Air Handler Flow

1 No limit*2 60%3 40%4 35%4 35%5 25%6 20%

*But be reasonable!  

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