Proposed Changes to PTCS Duct Sealing Specifications & Standards

RTF

January 23rd 2033

Bob Davis & Bruce Manclark

Current Specifications

• Systems must be sealed with mastic– Mastic comes out of a bucket - not off of a roll– UL 181 tape may be used to provide service access

• Worst case depressurization test must be below minus 3 Pascals• Must have UL listed Carbon Monoxide alarm if combustion

appliances are present• Testing must be performed by a Climate Crafter certified technician• Room by room heat loss required for duct sizing in accordance with

industry standards• No recommended changes

Current Tightness Standards

• New Construction– Total leakage or leakage@ 50PA to exterior

cannot exceed:• 6% of floor area (2,000 sq. ft. house max leakage

of 120 CFM) OR• 75 CFM

• No recommended changes

Current Tightness Standards

• Existing Homes – Achieve a 50% reduction in exterior leakage

@50PA by duct sealing– Leakage to exterior less than 10% of

conditioned floor area (2,000 sq. ft. house max leakage of 200 CFM)

– All pressure pans less than 1 Pascals

– Proposed changes: Eliminate the use of Pressure Pans as a standard

Why Eliminate Pressure Pans

• Not a solid standard

– Many variables other than holes to the exterior affect their readings

• Filter• Inside coils• Sq. inches of registers• Other inside leakage• Tightness of seal

(carpet vs. bare floor)

Why Eliminate Pressure Pans

• Crews receive inconsistent feedback

– Small reductions in holes may mean large pressure pan reductions

– Large reductions in holes may mean small pressure pan reductions

• Impossible to make energy savings projections from pressure pan numbers

Side by Side Comparisons of Pressure Pans and Duct Blasters

• 141 unsealed duct systems in western Oregon– All crawl space homes– Only shows average pressure pan numbers

Duct Leakage to Exterior @50PA141 Site Built homes

0

200

400

600

800

1000

1200

1400

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Average Pan Number

Ex

teri

or

Le

ak

ag

e C

FM

50

Mobile Home Data

• 41 mobile homes in Eugene, Oregon– Good variety of double wides and single

wides– Good variety of ages– Pre and post results on same homes

Mobile Home Exterior Duct Leakage @50PA for Fail and Pass Rule - all Pans < 1Pa

0

100

200

300

400

500

600

700

800

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

Chart ID Number

CFM

@ %

PA

fail pass

Duct Leakage to Exterior @50PA With all Pans <1 PaMobile Homes

0

50

100

150

200

250

300

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Chart ID Number

CF

M@

50P

a

% of Floor Area of Duct Leakage to Exterior @50PA all Pans Below 1Pa - Passed Pressure Pan Rule

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

30.0%

35.0%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Chart ID Number

Perc

ent o

f flo

or a

rea

% of Floor Area of Duct Leakage to Exterior @50PA at least one above 1Pa - Failed Pressure Pan Rule

-5.0%

5.0%

15.0%

25.0%

35.0%

45.0%

55.0%

65.0%

75.0%

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49

Chart ID Number

Leak

age

as P

erce

nt o

f Flo

or A

rea