Some contractors use special diagnostic tools to help pinpoint the source of common home problems. Some of these tools include:
A blower door is a variable speed fan, mounted in a doorframe, used to pressurize and depressurize a house to measure air leakage.
A duct blower is a variable speed fan that is attached to a duct system to measure duct air leakage.
An instrument that measures the pressure differences between two locations.
A Flow Hood is a device used to measure the amount of air flowing through a register.
An infrared camera (video or still) makes an image that shows surface heat variations that can be used to help detect heat losses and air leakage in buildings.