AIR LEAKAGE
Because HDPE QADUCT air ducts are new to the HVAC industry today engineers are applying current standards as a gap measurement.
We recommend the ASHRAE U.S.
Code Acceptance as a method to interpret Air Flow
pressure
SPC 118.2-1993R - Revision project committee
authorized 98/01/17, with same TPS ANSI/ASHRAE
119-1988 (RA 1994) - (Reaffirmation of ANSI/ASHRAE
Standard 119-1988) Air Leakage Performance for
Detached Single-Family Residential Buildings
PURPOSE:
1.1 This standard establishes performance
requirements for air leakage of residential
buildings to reduce the air infiltration load.
See DOE IECC changes or
DOE Site
1.2
This standard provides a method to classify the air
tightness of residential buildings.
2
SCOPE
2.1
This standard sets upper limits of leakage area and
provides a method of classifying air tightness for
detached, single-family residential buildings.
2.2
This standard does not apply to buildings which are
conditioned for human comfort less than 876 hours of
the year.
2.3
Although this standard is intended to reduce energy
use associated with air leakage through the envelope
of residential buildings, use of this standard may
preclude the use of air infiltration alone to
achieve adequate indoor air quality. The reduction
of air leakage is separate from the need to provide
adequate ventilation, adequate combustion air and
adequate indoor air quality. Consideration of these
issues is the responsibility of the user.
Measuring Characteristics IAQ
QADUCT™ is an engineered high-density polyethylene
plastic ductwork system which together with clamp
and gasket is air-tight, more energy efficient
air-transfer system than traditional metal ducts.
But energy efficiency is not the only benefit, the
goal is to improve air quality by also reducing air
infiltration and RADON.
Two goals to keep in mind, tightening the house and
maintaining indoor air pressure at 2 Pascals (0.008”
water column) relative to soil gas pressure. Radon
level at 1.7 pCi/L, can be reduction by 93%. This is
similar to results achieved by EPA scientists who
reported reducing indoor radon levels by more than
90% in test homes by keeping indoor air pressure up
to 4 Pascals (0.015” water column) greater than the
surrounding soil gas pressure.
(also see “Radon Reduction Techniques for Detached
Houses”, Page 154, EPA/625/5-87/019).
This calculation serves to indicate the Duct Pressure class required. In this case, it will be seen that Class 3 SMACNA leakage rate is 0.15 L/s per m2 against 0.121 L/s per m2 required.
Manometers
measure a pressure difference by balancing the
weight of a fluid column between the two pressures
of interest. Large pressure differences are measured
with heavy fluids, such as mercury (e.g. 760 mm Hg =
1 atmosphere). Small pressure differences, such as
those experienced in experimental wind tunnels or
venturi flow meters, are measured by lighter fluids
such as water (27.7 inch H2O = 1 psi; 1 cm H2O =
98.1 Pa).
Duct System performance shall not exceed SMACNA’s Leakage Class 3 requirements at the system design static pressure as indicated on the exceed -20 in or +12 in W.G. Read More
References
QADUCT components are constructed per SMACNA’s
Duct Construction Standards for to operate on air
leakage design tightness at 0.1 inch minimum water
column pressure. For better comfort, the performance
system can reach 10 inches water column pressure @
5000 cfm with better sealing. We recommend
MAXSEAL with AKDUCT clamps. For further technical
information please contact us
support@cdcei.net
High Velocity systems are measured at 600 CFM
at 1.5” in W.G. Standard Pressure.
Conclusion:
Soil gas pressure under a typical building is higher than outdoor air pressure, so keeping indoor air pressure higher than soil gas pressure will also keep indoor air pressure higher than outdoor air pressure.
Content prepared by Luciano Management, Published in agreement with sources; Energy Star, DOE, SMACNA, ASREA, ICC, UMC, ACCA Manual D & Manual J