Take the guesswork out of greenhouse ventilation.  The Bayliss Standard Triple Spring solar powered roof vent opener has been designed for aluminium or timber framed hinged vents measuring up to approximately 2 ft square (60cm square) and can be used in any greenhouses.

It fits neatly, close to the glass/polycarbonate greenhouse roof, consequently taking up less head room than a normal stay on a roof vent. The unit is 11 1/2" long (excluding the hexagon adjuster seen in photo on the right of the autovent). This model will operate a vent exerting a load of 14lbs (6kgs) at the point where it is attached to the vent, and can be set to start opening the vent at temperatures between 55F (12C) and 75F (25C), giving a maximum vent opening of approximately 12".

Please note:  Shipping charges will apply when ordered separately.  Not compatible with Juliana Greenhouses.