Solar greenhouse vent opener-Superior Autovents

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

Solar Powered Automatic Greenhouse Vent Opener from Superior AutoVents
Click here to order the Bayliss MK7 online – free shipping

Bayliss MK7 Automatic Greenhouse Vent Opener

Automatic greenhouse vent openers by Bayliss Autovents are widely thought to be the best on the market, suitable for both wooden and aluminum greenhouses. Adequate ventilation is an important aspect of greenhouse growing and this solar powered automatic greenhouse vent opener ensures accurate, continuous venting all day and night. 

Bayliss Autovents have been producing automatic greenhouse vent openers in England since 1964 and have 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 Orchid wax tubes.)
  • Greenhouse vent opener with wind strapCan lift hinged vents up to 30lbs. Our single spring units  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

Click here for vent opener price info

What Does An Automatic Greenhouse Vent Opener Do?

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

Guaranteed For 2 Years

Each greenhouse 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 power tube), damaged by the vent 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 replace it free of charge if it is returned to us. A failed power tube can also be replaced. Bayliss automatic vent openers are designed and tested to last many years.

How Does the vent opener Work?

Single spring greenhouse vent opener

Single spring opener

Triple spring greenhouse vent opener

Triple spring vent opener

A strong metal tube contains wax which expands with heat. This pushes a piston whichpens 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,  avoiding any sideways thrust on the vent which can damage it.

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

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 is more cost effective. We sell replacement power tubes. Give us a call to see if that is a good choice for you.

Click here to place an order online – free shipping

Or if you would rather talk to a person, simply call us at 1-800-334-4115 or 503-244-4100 with your credit card Monday – Friday 8am to 5pm PST

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

Our PDF can be difficult.  The best way to use it is to save the blank PDF on your computer, then open the saved PDF using Adobe Reader. You should be able to fill out and save the form now. 

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

Visit Us

If you’re in the Portland, Oregon area, please stop by our showroom! We’re open Monday through Friday from 8:00am to 5:00pm PST and weekends by appointment.

11304 S.W. Boones Ferry Road Portland, OR 97219

503-244-4100 or 800-334-4115

Get directions >

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