A greenhouse vent opener provides ventilation for plants, such as when a greenhouse becomes too warm during the day. Choosing the best opener requires consideration of the greenhouse's construction and the surrounding weather patterns. The greenhouse vent opener's physical operation and construction should also be examined to prevent overheating of sensitive plants.
Each greenhouse has different materials that make up its structure. Lightweight greenhouses, such as those constructed of plastic, can use a vent opener with a single spring support. The roof or side openings will be easily supported as warm-air escapes, allowing cooler air to infiltrate the interior space. Heavy-duty metal greenhouse frames, which hold glass, will require a triple spring support or hydraulic cylinder. Experts say that a pressurized piston within the hydraulic cylinder supports the heaviest greenhouse construction materials.
Weather patterns also dictate the best greenhouse vent opener. Excessively windy areas, such as within mountain passes, must use the triple spring or hydraulic cylinder vent openers. The lightweight vent openers can break or bend in strong winds, causing the greenhouse openings to close suddenly. Sudden closures can damage the greenhouse structure as well as the plants.
Examine the greenhouse vent opener's physical assembly before purchasing it. Triple spring supports will not be effective against winds or heavy greenhouse parts if the screws are not tightened correctly. The vent opener should be firmly constructed with no loose parts. You can shake and pull at the spring mechanism to ensure that it is a strong product.
You also should verify the breadth of the vent opener's operation. Some openers crack the opening by only 12 inches (30.5 cm), but others might open to 18 inches (45.7 cm). High-wind areas might require a smaller opening to avoid damage to the greenhouse as the wind shakes the opener and window combination.
Manufacturers commonly offer two greenhouse vent opener types, either manual or automatic. Manual vent openers require the greenhouse owner to physically turn a handle, much like rolling up a manual car window. The drawback to a manual vent opener is that an owner must be present when the greenhouse becomes warm. Greenhouse owners who work elsewhere during the day might subject the plants to overheating because they cannot be present at all times.
An alternative greenhouse vent opener is the automatic type. Automatic openers use heat-sensitive minerals within an enclosed cylinder for heat detection. Excessive heat causes the mineral to expand, directing the opener to enlarge the roof or side window opening for ventilation. Homeowners do not need to be home to monitor the greenhouse heat. The automatic opener will not affect the monthly electricity bill since it is powered specifically by solar energy.