Harbor Freight Automatic Vent Opener

We installed a Harbor Freight Automatic Vent Opener in November. In Texas, November is warm enough that the vent needed to open in the afternoon. Now we are having an unusually cool December. We have turned the knob adjustment as far counter clockwise as it will go without falling out. If there is any sunshine at all, the vent is still opening when it may only be 40* outside. I would prefer heat to build up so that the heater didn't have to run so much at night.. Have any of you figured out an easy way to disable the opener without taking it apart? My DH is suggesting he might drill out the pin and replace it with a cotter pin. Has anyone tried this? In central Texas, we really can't take the opener apart for the winter and put it back together in the spring. We may be cloudy and 40 one day and two days later be 75 with bright sun. Any experience with this problem? Thanks.

I have an auto-opener as well, but not from HF, so I don't know how their's is put together. Perhaps you can turn the know the opposite way completely, and then manually force the shutters/louvers to close somewhat. If that can be done, when you turn the knob to other way, the louvers might now close correctly. Play around with the opener and see if this idea has any value. You might also be able to shorten the rod that connects your closing mechanism with the louvers.

Also, do you know whether your opener has a hydraulic piston or some other mechanism (spring loaded)? For me, here in NE Mississippi, I have my GH's completely wrapped in Solar Blanket material, so my auto-opener, even if it opens, allows no cold air in. So there is no reason you can't simply cover the outside of the louvers with plastic and remove it when spring arrives. If your temperatures are getting into the 90's, this won't work IF that's the only ventilation you have. I use lots of fans, so heat is never a problem during the winter months, other than having enough of it. LOL

If you can take good pictures, or there is some schematic that is available for your particular auto-opener, post them and let's see what that shows.

Ken

Ours was a similar, but not identical problem...the wax cylinder on the HF automatic opener melted in the summer heat...Apparently it was operated through a wax expansion system..had to remove it and manually open it for the rest of the season. It was a real mess to remove, too!

DH bought hot/cold sensors from on-line (I think FarmTek) and we now have the sensors attached to the fans in the summer and the heaters in this kind of weather. He can change temp settings on the sensors so when it drops below 50 deg, the heater will automatically come on...and conversely in the summer, when the temps in the GH get over 85, the fan comes on...The sensors are easy to alternate between hot and cold (simple switch) and set for heat/cold limits...I think each one costs us about $30 when we bought one for each of the houses. That was 4 years ago, but DH bought a spare this year just in case...With this open, all I have to do is occasionally open a door -- much easier!

About 3 years ago, he purchased wireless temp monitors from Walmart. The sensors sit in the GH and the readers are on the kitchen window sill so I can monitor temps in the houses all day and if I need to go out, I can...heaters, monitors and wireless monitors all costs under $100...We would need 14 Automatic Vent Openers at $20 each...Hope this helps...

I found the same problem with my Bayliss openers. I also thought they were slow to close at sundown. Currently I just adjust the heat by opening the door a little. A thermostat controlled fan mounted in the highest part of the end wall is more reliable. The fan does not need to be large for early/end of season removal of excess heat. I am going to mount a dryer vent (4") in one end, with a 4" computer fan, I also purchased a thermo switch at Ace hardware for less than $20. Set at 80-85*F, I can absorb some of the excess heat in the GH before venting the rest.
I later plan to install a inward 10" shuttered fan with a poly tube for circulation and cooling, left running it circulates air and the shutters are on a thermo switch and open for inducting cool air. This can also be set high enough to retain some of the excess daytime heat.

I also use the indoor/outdoor thermometer to watch temps from in side the house.

This message was edited Dec 15, 2013 11:14 AM

Oh, I forgot the pic of the vent fan with tube
BTW you can construct a temp alarm by using a thermostat that can be adjusted down to 40*F or so, a battery pack/power supply, a doorbell and some thermostat wire. Easy to set up, not expensive, and gives you a chance to add alternative heat source.

I too have temperature sensors in each GH with the base unit in the house.

I ,like the doorbell idea. Never thought of doing that. I have installed "Emergency LED lights" in each GH. I have one GH on one breaker and the other on another one. IF there is a power failure, thus losing my fans and/or heaters, the lights automatically comes on and I can see that strong light from either my back doors or through a large, translucent, beveled-glass window in our bathroom.

Thank you all for sharing your information. We already have the wireless thermometer with the sensor in the GH and the readout in the kitchen. Very handy.

My husband has read all these suggestions and will use some of them. My GH is very small; (2 1/2' X 8' lean to). We were restricted in size because we have a boat parked in the side yard and had to leave room to get the lawnmower, wheelbarrow, etc. through. Some day I would like to trade the boat for a larger GH. LOL Except for the very coldest of nights, we are able to maintain adequate heat with a 32 gallon garbage can full of water heated with a 200 watt aquarium heater. That also causes evaporation for humidity. My main usage is to overwinter plants, but I am also starting a few seeds for a jump on spring.

As usual, we are probably over thinking this issue. It is not a matter of life or death if these plants don't make it, but I would really sad if they froze!! Here are pictures of my little project, showing that it is stuffed full. The blue barrel on the outside that you can see is for collection of water he drains from his aquariums, then I water my plants with it. Good fertilizer. Thanks again for the information. This is my first GH, so we are learning as we go.

Good start!

Yes, very nice starter, painting you water bottles flat black will help warm them. My old cast iron radiators are black for that reason.

Thanks to both of you. Spraying the bottles is on my list. Just hasn't made it to the top yet.

Thanks for information on the remote temp reader. I have the same problem here in California. We can be can close to freezing one night and then it's 75 the next day. During most of the year I just have my daughter open it up in the morning and then I close it before dark, but the weather this last month has been so crazy. I'd love to be able to monitpr the temp from the house which is a good 50 yards from the greenhouse.

I think you should be able to use one of the indoor/outdoor units, especially if you have a widow facing your GH. I have 3, 1 in GH, 1in garage, and 1 on the front porch. Most are rated for about 100 yds. Mine were not expensive, 2 came from Walmart and 1 from Radio Shack. Price ranges from $15 to $40. Mine is mounted in the GH at about 6' with a couple of small fans that run 24/7 to circulate air and equalize temps through out. By circulating the air, I also capture most of my solar gain in old cast iron radiators under the benches and have to vent very little of it.

Domehomedee--Before you buy a remote unit. be sure to read the range for that unit. Mine is a cheap one from Radio Shack and it said 160 feet. My distance is not an issue since I have a lean to greenhouse.

Any one---Am I going to get into trouble with fungus, insects, etc. if I don't continuously circulate air in my small GH?

You would benefit from using some form of fans, it will help prevent fungus, and keep temps and humidity uniform. I just use a couple of recycled 4" computer fans mounted near the peak. They were designed for continuous operation and use minimal power, usually 0.25 amps. You can also use your heat source as a passive means to circulate some air. If your benches have an open surface and your heat source is under the benches the rising warm air does the same thing, creating a draft up and around the plants.

As in nature, tropical plants (probably all plants) need air movement. I truly believe my success in growing all the hundreds of tropical plants is due to the fact that I have lots of air movement in my GH's. Chose a fan size that is proportional to your GH size. I am sure I overdo it, but in my "Orchid" GH, which is 10x12x8', I have two, 24" box fans and two, 18" oscillating fans, and during the winter months they run from 10:00 AM until about 4:00 PM. During the summer months they are on 8:00-6:00.

Good idea to measure the distance before I get to excited about any remote device. I will be adding a roof vent when I replace the plastic, something I could use in the summer that would be cheaper than running fans all day. Here's a pic of my set-up. This 12' x30 foot hoop house cost about $500.
This pic is from January 2013, the whole area off to the left is a fenced butterfly garden now.

Perhaps the roof vent would be all you need on the central coastal area of CA, but here in the deep south, that would never do. There would simply be too little air movement, particularly Nov-Feb because the GH's are typically closed-in. Then in the hot summer days, the temperatures would easily get into the upper 90's in the GH's, no matter how many vents were present. And those extreme temperatures are frequently obtained with shade clothes over both GH's. Without adequate fans, cacti would do OK, but little else.

P. S. I have a sister-in-law and her husband who live up in the hills of Arroyo Grande. Small world, huh?

They are probably our neighbors . . . it's not that big an area, LOL. Ask them if they know where Corralitos Canyon is.
Last summer the only thing I grew in the greenhouse was tomatoes and melons. And that was with all the doors and two fans going all day. During this time of year I put in potted tropicals, frost sensitive succulents and start perennial seeds. It still gets too hot to keep the doors closed all day even this time of year. I'd love a vent that would open and close itself, it would be all I would need six months out of the year. I don't heat, the greenhouse keeps it above freezing on those rare nights we get a freeze. I love my greenhouse.

Will do.

Very nice set up Domehomedee, The Bayliss wax cartridge openers may work for you. The closing is passive and not always solid. I will probably use mine again come warm weather.

D H built a 4x8 on the deck for my G H years ago . He put it with my kitchen window in the center . I set a fan in the window for extra heat in the winter from the house . A thermometer sat at the one foot level opposite from the window so I could keep an eye on the temp. There was a sliding vent door on the top , end . This may help you get through the winter if you can't solve the vent problem soon . I noticed your G H could be moved down so that a window is on the open side .I kept a small , electric heater on the floor with a thermostat

This message was edited Dec 31, 2013 10:41 AM

digger9083--Not sure if your post is addressed to me, but my GH is on a concrete footing and bolted down to a treated lumber foundation. Can't be moved over in front of the window. For the time being, we have disconnected the automatic opener. We are having colder than normal temps right now. I use a small electric heater on a wall mounted thermostat (which is slightly more accurate than the thermostat built into the heater). Am maintaining a minimum temp of 46.1*. Gets up to about 80 if the sun shines in the afternoon. Good temps for right now.

Didn't see the foundation , sorry . Right now I'm in Liberty Hill visiting my son and he has a dog , mean to my little dogs . We have an electric heater in our van to keep the chill off .Put his up , let ours out , and on and on . It has been so cold the last few days even the heater has been barely enough .My G H was in the mountains in N. Georgia . We didn't get the wind there , like here . Brrrrrrrr!

I've come up with a vent system for a small GH that works with covering the top and sides with poly of a solar cover. As soon as I build and install it, I will share it with you.

If you are still looking for a better way to control greenhouse equipment, I think an IoT solution to greenhouse control might interest you. There are a few companies who do this and its basically a system that can connect to all greenhouse equipment and allows you to control them on your computer or smartphone. You can check out Maple Smart Control if you're interested.

I also use the indoor/outdoor thermometer to watch temps from in side the house.


This message was edited Aug 16, 2021 4:27 AM

I started with harbor freight green house window openers. They are filled with a wax that expands with heat and pushed a push rod out that mechanically opens the window.
I also had problems with them. one started leaking in the second year. I still have a new replacement that I never used. instead, I removed them both and replaced them with a module that is used to open duct work in an air movement system. It opens both windows at the same movement. It is controlled by a common thermostat that would run a furnace but of course it isn't running a furnace but controlling this opener. It's very sensitive to temperature changes and can open or close in as little as 1 degree temperature change. I have my thermostat set at 10 degree temperature change. It is equiped with a spring return to make a sure closure when its not calling to have the windows open. If you loose power, it closes securly. It didn't cost much more than the two HF window openers and works wonderfully. Its been in place since 2008 and still functions as if it were new 15 years latter. This put an end to my worries and gave me a lot of piece of mind both on cold and windy days equally on hot days. My worries have been freed for me to continually check on the system. Now no more concerns. couple it with some remote thermometers and checking on the Green house is done inside my home. Well worth the investment.