Superior Autovent Opener

Sturdi-built Greenhouses is a US distributor for the Bayliss MK7 greenhouse autovent

Solar Powered Automatic Greenhouse Vent Openers from Superior AutoVents

The Bayliss MK7

Bayliss MK7 Greenhouse Automatic Vent Opener

Bayliss Automatic Greenhouse vent openers are widely thought to be the best automatic vent openers on the market, suitable for both wooden and aluminum greenhouses. Adequate ventilation is one of the most important aspects of greenhouse growing and this solar powered automatic vent opener ensures accurate, continuous venting 24/7.

Bayliss Greenhouse Automatic vent openers have been produced in England since 1964. The Bayliss Company has a reputation for quality and reliability.

Greenhouse vent opener fully open

The Bayliss MK7 automatic vent opener offers:

  • Corrosion resistant construction
  • Balanced lifting action
  • Illustrated fitting instructions
  • These openers have our special Superior Autovent tube with an adjustable beginning opening temperature of 65 – 75°F. Fully open at 20° higher. (Superior tubes open at a higher temperature than standard Bayliss tubes and at a slightly lower temperature than the Orchid wax tubes.)
  • Greenhouse automatic vent with wind strapCan lift hinged vents up to 30lbs. These are single spring units which work best on roof vents. We also have triple spring units which work for wall vents.
  • Wide opening up to 12 inches
  • Manufacturer’s 2 year Guarantee

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What Does A Bayliss Automatic Vent Opener Do?

Opens and closes a hinged vent automatically using energy from the warmth of the sun.

Guaranteed For 2 Years

Each automatic vent opener is guaranteed for two years against faulty manufacture. As long as the unit has not been tampered with (i.e. the piston pulled out of the tube), damaged by the window being tied shut, damaged by unusually strong high winds (add our optional wind strap to keep strong winds from damaging the opener) or fitted incorrectly, we will repair it free of charge if it is returned to us. Bayliss automatic vent openers are designed and tested to last many years.

How Does an Automatic vent opener Work?

A strong metal tube contains wax which expands with heat. This pushes a piston which opens the vent via a balanced linkage. As the temperature drops, the wax shrinks and a strong stainless steel 6½lb spring (Triple Spring units have (surprise!)3 springs) which closes the vent and resets the piston. Single spring units work well on roof vents where gravity helps close the vent. For wall vents, you should use Triple Spring MK7 units. We have these available as well. Call or email for information.

Why Is The Bayliss Automatic vent opener better?

It has been designed by engineers who have been making automatic vent controls for over 40 years. The Bayliss MK7 has a strong stainless steel spring to give a firm closing force. The unit gives a balanced lifting action in the middle of the vent and this avoids any sideways thrust on the vent which can twist it or even push it out of position.

Do you have an old Bayliss opener that just doesn’t seem to open like it used to?

It could be that the power tube has lost wax or pressure. If the vent opener isn’t bent or damaged in some other way then you might be able to simply replace the power tube which should be more cost effective. We sell replacement power tubes. Give us a call to see if that is a good choice for you.

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To Place an Order:

Simply call us at 1-800-334-4115 or 503-245-5650 with your credit card Monday – Friday 8am to 5pm pacific time

By Mail, send order form with check to:

Sturdi-built Greenhouses/Superior AutoVents

11304 SW Boones Ferry Rd.

Portland, OR 97219

By email: Fill out Order form PDF and email to

By FAX 503-293-9266 Fill out the order form PDF and fax to us

Click here for vent opener price info

Visit Us

If you’re in the Portland, Oregon area, please stop by our showroom!
We’re open Monday through Friday from 8am to 4:30pm. Weekends by appointment.
11304 S.W. Boones Ferry Road
Portland, OR 97219
Get directions >

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