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The multi-point blower door test procedure results in a series of known values of Q n, Fan and ∆P n, Building. Typical ∆P n, Building values are ±5, 10, 20, 30, 40 and 50 pascal. Ordinary least squares regression analysis is then used to calculate the leakage characteristics of the building envelope: C Building and n Building .
A third test method to determine if ductwork is leaking to the outside is to use a pressure pan, which is a register cover with a pressure tap for a hose connection. With the house pressurized (or depressurized) to 50 Pa (-50 Pa) using a blower door, a pressure gauge is attached to the pressure pan by means of a hose.
Smoke candles and blower-door tests can help identify less-than-obvious leaks. The Weatherization article describes methods for energy savings further. If infiltration is reduced below 0.35 ACH, it is recommended that mechanical ventilation (typically an exhaust fan or heat recovery ventilation ) be implemented.
Building airtightness levels can be measured by using a fan, temporarily installed in the building envelope (a blower door) to pressurize the building. Air flow through the fan creates an internal, uniform, static pressure within the building.
A typical commercial air curtain enclosure. In North America, the more commonly-used term for an air door is "air curtain". The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) defines an air door as follows: "In its simplest application, an air curtain is a continuous broad stream of air circulated across a doorway of a conditioned space.
Centrifugal fans often contain a ducted housing to direct outgoing air in a specific direction or across a heat sink; such a fan is also called a blower, blower fan, or squirrel-cage fan (because it looks like a hamster wheel). Tiny ones used in computers are sometimes called biscuit blowers. These fans move air from the rotating inlet of the ...
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Air handlers typically employ a large squirrel cage blower driven by an AC induction electric motor to move the air. The blower may operate at a single speed, offer a variety of set speeds, or be driven by a variable-frequency drive to allow a wide range of air flow rates. Flow rate may also be controlled by inlet vanes or outlet dampers on the ...