Bayliss Autovent Opener

Item No. GA-1007
Free Shipping See Details This non-electric roof vent opener is simple to install and is completely automated. A threaded adjuster bolt can set the Bayliss to start opening the vent at approximately 55 degrees fahrenheit. This vent opener uses a very simple principal - Special waxes have an
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Free ShippingSee Details

This non-electric roof vent opener is simple to install and is completely automated. A threaded adjuster bolt can set the Bayliss to start opening the vent at approximately 55 degrees fahrenheit. This vent opener uses a very simple principal - Special waxes have an expansion rate of about 18% when heated by the sun. As the air in the greenhouse heats up it also heats the powertube in the vent opener. As the wax expands it pushes out a stainless steel piston that slowly opens the vent up to 13 inches. The hotter the temperature the wider the opening. When the temperature cools the weight of the vent and a 6 1/2 pound stainless steel spring closes the vent and holds it closed.

Additional Information


Bayliss Autovent Opener (PDF)

Free Shipping 

This item ships free - almost anywhere in the Continental United States!

On rare occasions addresses with limited access such as islands or major metropolitan areas (ie: New York City) may incur additional delivery fees; if so, you will be contacted to confirm the extra shipping cost before your order is processed. Shipments to Alaska or Hawaii qualify for free shipping to any West Coast port. Please contact us for special shipping rates from the West Coast to Alaska or Hawaii.

LTL Freight Type FREE
Replenishment System Purchase
Available for Drop Shipment No
Reviews (28)
  • Baylis Autovent Opener
    Working wonderfully!
  • It works
    The Bayliss Autovent Opener works. It opens a window when it gets hot. I just wish it it opened the window wider. Is there a way to reconfigure it for more throw?
  • Baylis autovent opener
    They work excellent I have two of them, one on each end of the greenhouse. once you dial them don't have to think about it again.Love it
  • Bayless Autovent opener
    Bought unit as a replacement for existing Bayliss units. They fit and worked great.
  • Replacement vent opener
    The part did not fit my greenhouse exactly but I did not expect it to. With a slight modification I was able to install it, and it worked perfectly. Much better quality than the part it replaced. Definitely would shop this company again.
  • Seems to work
    Put this on my little Palram Hybrid greenhouse. This product was not specifically designed for this greenhouse so it took some extra hardware and ingenuity to get it attached. Palram does offer an auto vent opener that would attach must easier, but it didn't look like adjusting the opening temperature was possible with that one. On this one, you just tighten or loosen the adjuster knob and it will open when you want, that's a very nice feature. Only had it on a week but working so far.
  • Bayliss Autovent Opener
    I liked it so much better than the one that came with my greenhouse that I ordered another one. It works well and is much easier to set for the temperature you want.
  • Mr
    Works well, easy to adjust for opening temp. This is replacement for original. I have found I can buy just the operating piston for only $31.
  • wrong model Bayliss
    My greenhouse window hangs vertically from a horizontal hinge. Instructions say a different model Bayliss with more springs should be used in this application. Catalog should warn the buyer and offer the alternative model. Ventilator works fine anyway. If more closing force is needed then a better way than springs to provide it is a weight hanging from a horizontal lever projecting outside from the hinge pin. That way, the ventilator can still open fully. Spring F = kX. Avoid increasing k by using 3 springs instead of 1.
  • Excellent Product!!!
    My Bayliss Autovent was very easy to install. It works mysteriously GREAT! No complaints! It has been working now for a couple of weeks with no issues. Figuring out when I want it to open has been a little tricky - but logically expected! Thank U GhMS for your excellent prices.
  • returned
    only gave it a two because it appears well built have sent back because it did not work right out of the box hope the quality control is better on the next on also i think a bit expensive for what it is
  • mislead
    i have been using an opener on the roof vent of my greenhouse for years, love it. i just purchased one to use on a side window and it will not hold it closed. directions say to use a triple spring model for side windows. This rating is for greenhousemegastores misleading description.
  • Non-electical vent solution-Slick!
    Installed 6 Bayliss Autovents in my new glass greenhouse in 2010. They have performed flawlessly now for almost 4 years. They shut the vents at night and open them in the morning when the sun starts to warm and expand the plastic-filled cylinder in the Autovent. And without any need for power! A 5-star solution.
  • wonderful
    works just as advertized, like magic.
  • works perfect
    works like magic....amazed when I come home to see the vents opened to save my plants, then to close as the sun sets. Highly recommend this product. w
  • good unit
    Works fine. The mounting for the snap-n-grow was difficult. a couple longer t-nuts instead of drillpoint screws would work better.
  • Bayliss Autovent Opener
    Love the autovent openers, they make temperature control so much easier in my green house!
  • bayliss auto opener
    i bought this autovent opener for my greenhouse and it'll start to open the window, but once the window is cracked open and the wind hits the auto opener it won't open any further and then it heats up way to much in the greenhouse. unless i don't know what i'm doing i wouldn't recommend this product to anyone, especially for the price.
  • packaging manager
    works well and installed easily.
  • Bayliss autovent opener
    I love this product! It works EXACTLY as advertised and has been a life saver for my plants. I live in Florida and the weather this year has flucuated dramatically between extremely hot and cold. I can depend on this opener to adjust the vent to cool off my (small) greenhouse when I'm at work and close when it's cold. It didn't fit exactly on my greenhouse, but with a little adjusting, it works great. Probably too much for my little house, but just what I needed! Very well made.
  • Great piece of hardware
    Very versatile piece of hardware. We have used this on several greenhouses, and several styles of vents. It lends itself to just about any type of installation you can think of. Just stay within the weight limits.
  • Love it!!
    The opener that came with my hobby greenhouse never worked very well. The Bayliss is probably more opener than I needed but I love it. I'm confident that it will always work properly. Greenhouse Megastore was great to purchase from. I will definitely buy from them again!
  • This really works
    I was skeptical when I bought this but it works great.
  • happy with the vent
    Installation was quite easy. It doesn't open as much as the 12 advertised as possible, mine opens to about 8. Also wasn't sure if I needed more space below the opener - at what angle it would open. I had a rafter board that it was mounting above. But there doesn't seem to be an issue.Now I can leave town and at least one thing will take care of itself!
  • Automatic opener
    This opener was easy to install and has worked flawlessly since being installed.
  • Must have if you own a large Greenhouse
    I was in the habit of opening and closing my vents in AM & PM. I ordered the Bayless AVO & it worked like a charm. No power necessary and I can depend on it.So great! How great. Well, I ordered the second one for the other vent. Both are totally auto. now! Thanks Bayless
  • love it
    i still need to buy more they are so nice to open by them self and close when it gets cooler this is what every person who has a green house they need to buy them
  • GA-1007