And in the same house, one also wants to see how leaky the ducts are to the outside of the house and to the basement. It is advantageous to run the series of tubes from each of those locations back to a central location, such as near the blower door. The idea behind using a pressure manifold may sound confusing at first, but with some field practice, almost anyone can design and fabricate one. It shortens field time and helps to keep track of what one is doing. When combined with an appropriate data-entry form, many results can be obtained in minutes once the hardware is in place.
Variety is the spice of multizone testing.
We typically begin by preparing a dwelling for blower door testing. We run an extension cord to the air handler so we can switch it on and off from a manifold and manometer. We then run a series of tests in an orderly sequence, measuring six to eight pressure differences under each configuration. In the interests of efficiency, we usually vary only one or two parameters between tests. For example, a first blower door test is run with the basement door open, a second with it shut, a third test with ducts sealed and the outside basement door open, and so on.