The vents and heater should not really be battling each other. If the vents are set to open at say 80 deg and you are planning to heat your greenhouse to say 70 deg. in the winter, the vents should not open. If they are not adjustable and open at a relatively low temperature, then it is usually a simple matter of pulling a cotter pin on the vent to release the mechanism. Note that if you are not planning on heating in the winter, most vent openers advise in the instructions not to leave them in place. The wax/parafin/oil filling in them is not designed to be frozen.

We are planning to heat the GH all winter. How do you set them to open at a certain temperature? There are no numbers or temperatures or anything on them. I would like them to open at 80F. How is that done? They do have a thing you turn on the bottom of the cylinder that raises or lowers them.

Do I close them and then wait for it to be 80 F and turn the adjustment thing? Do I turn it until they're open all the way? If so, at what temperature would they close?

No directions at all came with them except how to install them.

greenhouser - The "thing you turn" is how you adjust the vent openers. As you note, you will have to adjust them when the temps. are at the levels you want them to open/close. If you want them to be fully closed at 79 deg and start to open at 80 deg. then make your adjustments to just start opening when the greenhouse just reaches 80 deg. As you point out, there is usually no scale on the openers themselves, so you have to adjust them based on the current temp. in the greenhouse. It is really a lot easier than it may sound. You only have to be there for the adjustments when the greenhouse is approaching 80 deg.

Thanks again. (As you can imagine I never could learn how to program the VCR or Mircowave.) With the hot days and nights here now, they stay open 24/7. So at 80F I turn the adjustment to the point where the vent is open just a wee crack? I assume they'll continue to open as long as it's 80F or above and start to close when it drops below 80F. Am I correct? If so then it shouldn't be fighting it out with the heaters which will be set around 60F somewhere. I think the light dawns.

I would love to have them work like that all winter so I don't have to dash out in my nightie in the cold morning to open vents by hand.

What I would like to have are vent openers that operate off a thermostat, like the small motors that operate the shutters on the intake vents, so if anyone knows of any and where to get them, please post that info.

Perhaps it's just me, but I'm finding that the more automated I can get the mechanics in my GH, the more time I have to play with my plants and fish, and the freer I feel to take off for a few days and not worry about coming home to a disaster, just because weather predictions were off.

greenhouser- sounds like you have it right.

b.w.- They do make electric vent openers, but they are expensive. I found a link in england. Just double the price in pounds and you get the dollar price.

Here is a link that might be useful: electric vent openers

I understand exactly what you're saying. My greatest fears are either cooking my plants (can't get to the vents in time) or freezing them to death if we lose the electricity in the middle of a winter night. I would truly be afraid to leave home in the winter to stay overnight anywhere. Since they spend the summers outdoors I feel ok with leaving them for a long weekend.

Last winter I had to check my HFGH twice a day. In the morning I went out to open the vents and door a crack. It would already be close to 100F some mornings. Then at sundown I watered them and closed it up for the night, turning the heater back on.

Cuestaroble: Thanks for the link, but with 4 roof vents, I'll have to keep looking.

Greenhouser: Put enough of your heart, soul and money into a GH, and the cost of a gasolene powered standby generator will be more than justified.

We bought a portable one at Sam's Club a few years back that has paid for itself several times over, just in running the furnace fan in winter, and the freezer and fridge in summer.

It also saved a lot of my fish, by powering my big air pumps for 2 days, while Comm. Ed made excuses.