That makes it cheap insurance against tragedy. Digital manometers are more expensive, but often make sense for HVAC contractors or energy specialists. Digital manometers can be purchased from Infiltec , The Energy Conservatory or Modus Instruments, Inc . With this simple 15-minute test you can increase customer safety and satisfaction, as well as reduce callbacks and exposure to liability claims. David Brook is an extension agent with the Oregon State University Extension Energy Program.
Wind is one natural force that causes air pressure changes in a building.
Even when the wind isn't blowing the building can create its own negative pressure through a process called the stack effect. When there are holes in the building envelope near the top of the structure, warm air escapes through these openings while colder air enters the building through lower openings. The best defense against the stack effect is to carefully seal your homes against air leaks. Mechanical equipment can also cause negative pressure. Unbalanced air flows between the return and supply sides of a duct system may be caused by leaky or disconnected ducts, by blockage in the ducts or by closed interior house doors that block air flow between supply registers and returns.