I love my Bayliss.

Dan

Love the Univent have 8 of them in GH for 4 years. Have had no problems

I have a couple Univent - seem to be the best value.

I've also had good experiences with Farmtek - great customer service.

I'll be looking for some this spring. Not sure if I should just get the replacement cyclinders and wing it or spend the 50+ for each one. I'll be needing 5 units.

Which ones lift the most weight and close up tightly? Is it true that subjecting them to winter temps can damage the wax?

Bayliss has a "Super" that says it lifts 65 pounds and there's another like it called a "Giga" vent that says it lifts 35 pounds. I think the 65 pounds is actually referring to the entire weight of the vent, but the 35 pounds is referring to the force needed to lift it on the hinges. Basically, I think they lift the same amount, but I may wrong about that. Most of the other "standard" vent openers lift about 15 pounds which I think is the force they'll lift, so they'll lift a 30 pound vent, but again, I may be reading it incorrectly. My vents need 19 pounds of force to lift them (they weigh about double that), so I'm trying to decide between one "Super" or two "standards" per vent since the vents are 6 feet long. I think that two standards will give better support since they are so long, but Bayliss says they won't guarantee them if two are used on one vent.

As far as winter - most websites say that you should remove them for winter, but the Bayliss website says that removing them in winter is unnecessary.

How would you make the replacement cylinders work by themselves?

yeah, the HF openers are junk...some of mine only lasted a couple of months. I built my own. ;-)

Here is a link that might be useful: auto openers

The Peaceful Valley catalog has an automatic vent opener that lifts 32 lb, opens 18" and sells for $34.99. I do not see a brand model listed. There is also a listing for a GIGAVENT which lifts up to 65 lbs and sells for $119.00 each. I'm ordering 2 of the less expensive models for my HF 10' X 12'. I'll need 4 but thought I'd check out the quality first.

Ron - note that that 32lbs most likely means it is capable of opening vents that weigh 32lbs, and assumes that half the weight will be supported by the hinges. This means that the true lifting power of the opener is most likely 16 lbs.

Thanks ryangrogers for that info. I'm not sure how much these vents weigh and short of dragging out the big ladder and removing and weighing one I'm going to guess that they won't be 16 lbs. I'll only order 1 now. The HF design has a pivot lip that rotates in a circular channel. Lots of room for friction.

I'm a fan of HF, but as Web4deb stated, the HF automatic vent openers are less than satisfactory. Because they are cheap I've installed three or four; they all crapped out. However it should be noted that my greenhouse is located in Tucson, AZ and the summers are hot.

snoggle, I can make the brackets myself. All I need are the cylinders. It pays to have steel and a welder lying around!

Ron62 - You don't have to take the vent's off to check their weight. I took our digital bathroom scale and taped a plastic cup to it upside-down and set it to zero. Then I opened up the side vents and held it up with the cup-scale combo. This told me how much force it takes to hold it up. It probably weighs about double that.

snoggle75-That's a good idea. Thanks.