Janssens Automatic Opener

Description

The Janssens Automatic Opener is a simple upgrade for gardeners who want more consistent ventilation without having to manually open and close greenhouse vents throughout the day. It’s a great fit for anyone who wants to improve airflow, help regulate heat buildup, or make venting a little more hands-off when life gets busy. Whether you are upgrading a roof vent or adding automatic control to a louver window, this opener helps your greenhouse respond more naturally to changing temperatures.

Inside the black cylinder is a special paraffin oil that expands as the temperature rises. Once the greenhouse reaches around 72°F, that piston pushes the vent open up to about 14 inches. As temperatures cool down, a heavy spring pulls the vent closed again. No electricity or batteries are needed. For greenhouses in higher wind areas, or for Victorian Hybrid models with polycarbonate vents, the Heavy Duty Opener is recommended because its stronger springs help resist wind gusts and reduce stress on the vent system.