Price: $87.95
Availability: In Stock - Usually ships in 1 to 2 days.

The Bayliss MK7 Hydraulicheck solar vent opener is the best choice for greenhouse vents in high wind areas. A built-in hydraulic damper prevents the vent from being wrenched open by high winds. The damper only allows gradual opening but it can shut quickly. The Mk7 Triple Spring model offers an adequate degree of protection in most cases but, greenhouse vents can suffer wind damage in severe conditions. The solution is the hydraulicheck fitting which has held up in winds of up to 90mph. Two heavy-duty return springs provide positive closing action. Opening temperature is adjustable (Ranges shown below). Maximum opening of 12" is reached at approximately 20° to 30°F above opening temperature. Bayliss MK7 vent openers are made from the best corrosion resistant materials: stainless steel, anodized aluminum, and brass.

Bayliss MK7 Hydraulicheck Features

  • Adjustable initial opening temperature range: 55° F to 70° F
  • Maximum opening of 12"
  • Recommended for vents up to 30 lbs. total weight
  • Equipped with hydraulic damper for windy locations
  • Made in the United Kingdom

How does a Greenhouse Autovent work?
A strong metal tube contains a mineral wax which expands with heat. This pushes a piston which opens the auto vent via a balanced linkage. As the temperature drops, the wax shrinks and a strong spring closes the vent and resets the piston.

Product Manuals, Tips, Specs, & Guides

Bayliss MK7 Vent Opener Dimensions
Bayliss MK7 Vent Opener Installation Manual

Bayliss Opener Operation
Overall Customer Rating of 2 Reviews:
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Western Michigan

Solar vent opener

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I made a cold frame and installed the unit so that the top would open when it got too hot inside. Seems to work fine. My only complaint is that it would be really helpful if the opener had a quick release mechanism to separate the top and bottom parts. Right now, I have no means to easily open the entire top because it's completely attached to the main frame with the solar opener. How do I plant or harvest since I can't open the top more than the 12" that it does when hot?

ACF Greenhouses: Bayliss openers are not made for your application. We recommend the Univent opener for cold frames. It has a quick disconnect feature and larger 18" opening.

New Jersey

after a long search...

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I work at an assisted living facility and our residents manage a greenhouse on the property. One of the autovents malfunctioned last year and we have been manually opening the vent ever since. The product that we purchased was exactly like the one that broke. It arrived two days after I ordered it and took ten minutes to install. Going forward, all of our greenhouse needs will be coming from ACF Greenhouses. Thank you!