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Duct leakage test in the US. A duct leakage tester is a diagnostic tool designed to measure the airtightness of forced air heating, ventilating and air-conditioning (HVAC) ductwork. A duct leakage tester consists of a calibrated fan for measuring an air flow rate and a pressure sensing device to measure the pressure created by the fan flow.
Duct leakage testing of forced air heating/cooling systems - both supply (vents) ducts and return ducts can be tested to determine if and how much they leak air. A duct test can be combined with a blower door test to measure the total leakage to outside, measuring effective leakage to the outside of the house only.
The leakage test method for system commissioning is described in EN 12599. [8] In the US, leakage classes 48, 24, 12, 6, 3 as defined by ASHRAE are commonly used; ASHRAE also gives recommended acceptance criteria based air leakage as a percentage of fan design airflow at maximum operating conditions. [9]
The relationship between pressure and leakage air flow rate is defined by the power law between the airflow rate and the pressure difference across the building envelope as follows: [16] q L =C L ∆p n. where: q L is the volumetric leakage airflow rate expressed in m 3 h −1; C L is the air leakage coefficient expressed in m 3 h −1 Pa −n
UFAD leakage that does not contribute to cooling, leading to wasted increased fan energy. UFAD leakage into the space, contributing to cooling. Leakage in UFAD supply plenums can be a major cause for inefficiency in a UFAD system. There are two types of leakage—leakage into the space and leakage into pathways that bypass the space.
It applies to a fan or other air moving device when air is used as the test gas with the following exceptions: (a) air circulating fans (ceiling fans, desk fans); (b) positive pressure ventilators; (c) compressors with inter-stage cooling; (d) positive displacement machines; (e) test procedures to be used for design, production, or field testing.
In heating, ventilation, and air conditioning (HVAC), testing, adjusting and balancing (TAB) are the three major steps used to achieve proper operation of heating, ventilation, and air conditioning systems. TAB usually refers to commercial building construction and the specialized contractors who employ personnel that perform this service.
In cold climates, with a 15 MPH wind, residences often have air exchange rates of 1.0 to 1.5 ACHs, far in excess of the ventilation air needs and are thus called loose construction. It is very easy to reduce infiltration rates to less than 1.0 ACH. Smoke candles and blower-door tests can help identify less-than-obvious leaks.
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