Ventilation is perhaps the most important component in a successful greenhouse and without it any greenhouse can become too warm even in relatively cool weather. Gabriel Ash greenhouses and glasshouses are designed with this is mind and as standard come with full length automatic ridge ventilation in the greenhouse range and automatic roof opening lights in the glasshouse range.
The autovents on your structure are manufactured for Gabriel Ash by Bayliss. The metal piston contains a mineral wax which under increasing temperatures pushes the piston rod up opening the vent. The vent is set to start opening between 10°C and 12°C. They function in the warmer months of the year when the temperatures are high both inside and outside the greenhouse. Because they rely on the ambient temperature there will be occasions in late Spring and Autumn when it is not warm enough for them to open. These autovents are pre-set in the factory and should not require any adjustment.