What’s a Fan Door?

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A vent door detects air leaks in buildings. It includes a frame, fan, and pressure gauge to measure changes in air pressure. Results can help improve energy efficiency by adding insulation and sealing leaks. The device can also be used in commercial settings to test for leaks and verify positive air pressure conditions.

A vent door is a device used to detect air leaks in a home or building. Depending on how the building was constructed, it can include gaps and holes in the exterior that allow air to escape to the outside. To maximize energy efficiency, many homeowners attempt to seal as many of these leaks as possible to improve the airtightness of the structure.

Every blower door device has three basic components. A large plastic or wooden frame is inserted into the frame of an exterior door inside the building. This frame includes a specially made cutout to hold a fan or blower. A pressure gauge attached to the fan allows operators to measure changes in air pressure inside the building and outside. During a blower door test, technicians use the blower to add or remove air inside the home until a pressure change between inside and outside is detected.

Based on the volume of air required to create a pressure differential, operators determine how airtight the structure is. If a large volume of air needs to be added, this indicates that the house has a lot of air leaks, which is related to low energy efficiency. If only a small volume of air is required, the house is said to be well built, which is associated with high energy efficiency.

By evaluating the results of the fan door test, homeowners can then take steps to improve energy efficiency. This can include adding insulation to walls, ceilings and crawl space areas. It also includes caulking or sealing around pipe penetrations or at any joints in siding or roofing. Seals around doors and windows can also help keep air leaks to a minimum. These steps not only help reduce your heating and cooling bills, but they also improve comfort and reduce your consumption of fossil fuels like oil and natural gas.

After adding insulation and air sealing to the home, homeowners can retest the vent door to check for a change in air leak measurements. This device can also be used in a commercial setting to test windows, roofs and other structures for leaks. A blower door test can also be used to verify positive air pressure conditions within a building, which are required by many fire codes. In commercial facilities, the fan door can be applied to the building’s heating, cooling and ventilation ducts. These components are often subject to specific maximum air leakage rates based on local building codes.




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