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Blower door installation (France) Depending on how a blower door test is performed, a wide variety of airtightness and building airflow metrics can be derived from the gathered data. Some of the most common metrics and their variations are discussed below. The examples below use the SI pressure measurement unit Pascal (pa). Imperial measurement ...
Usually, a register is placed near a window or door, which is where the greatest heat/cooling loss occurs. [ 4 ] [ 5 ] In contrast, returns (grilled ducts which suck air back into the HVAC system for heating or cooling) are usually placed in the wall or ceiling nearest the center of 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.
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.
It is worth noting that ACH measured with the blower door test, at a differential pressure of 50 pascals, mimics the situation of a sustained 20 mph (32 km/h) wind outside. The natural air leakage, under calmer conditions, is likely to be much less. As a result, the so-called natural ACH may be a factor of 10-25 times smaller. [14]
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Small air handlers, for local use, are called terminal units, and may only include an air filter, coil, and blower; these simple terminal units are called blower coils or fan coil units. A larger air handler that conditions 100% outside air, and no recirculated air, is known as a makeup air unit (MAU) or fresh air handling unit (FAHU).
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