Retrotec Multi-Fan Blower Door - Manual (Page 11)

Page 11 of 37
©Retrotec Inc. 2015
Tubing configuration for pressure neutralization.
Both gauges should be in the hallway.
All pressures are referenced to a common Blue tube which is connected to outdoors via the stairwell where
at least one door should be open to outdoors. The Red tubes are measuring pressure in the hallway and the
apartment respectively.
Before the hallway blower door is turned on, the total apartment leakage is being measured by the blower
door in the apartment doorway. Then the hallway blower door is turned on.
The Left gauge and blower door establish a pressure at 50 Pa between outdoors and the hallway in this
example.
The apartment blower door will have to slow down to maintan a pressure at 50 Pa between outdoors and
the apartment. The pressure between the apartment and hallway wall is zero and has been neutralized. The
leakage across this boundary has also been neutralized forcing the blower door mounted in the apartment
doorway to read a reduced flow rate. This reduction represents the hallway to apartment portion of the
previous total apartment leakage.
This procedure is sometimes oddly called “guarded” blower door tests which is not a technical term even
though it’s sees common usage in the USA. Pressure neutralization or pressure nulling is truly the terminology
of what this method depicts.