NEED HELP with a project idea

[applestar]

I am seeing very high humidity in my high tunnel hoop house which has been as tightly closed up against drafts as possible.

I want to create air movement but there is no electricity access.

So I had a vague stirring of an idea to build and hang one or more kinetic mobile sculpture from the high roof rafter —

My idea is to combine the concepts and designs for

• plastic bottle windmills

• holiday candle spinner

• kinetic hanging mobile

…and make use of the thermal lift that hopefully occurs when the direct sun warms up the interior to stir the air around.

I feel like this should work, but does anyone have technical pointers? All three concepts are based on physics and science so there are probably some dos and don’ts?

For example, should the spinners be pointed up, down or sideways? Or more than one direction?

Would multiple spinners on one mobile cancel each other’s movements?

Should they occupy high space near the roof plastic, or should they be lower? Or should they be made long sculptures to hang from high to low space, nearly just above the plants or at least the low tunnels covering the plants?

I could probably hang 3 sculptures.

If you have made some large mobiles, I’d sure appreciate pointers since I’ve only made small ones to hang inside the house.

[Vanisle_BC]

Applestar, my thought is that humidity/condensation won't be alleviated without some venting; some air exchange between inside & outside.

But I could be wrong

[applestar]

You’re right I’m sure. Right now, the foundation vent installed on the bottom door panel opens when 70+°F and relieves some of the moisture issues.

What I want to do is create air movement to stir the “soup” a little. Both the thermal layers as well as humidity.

There is a bit of micro weather going on in there already since the condensation drips from the ceiling/roof.

[TomatoNut95]

My old greenhouse model had two vents at the top of the front and back to let out heat/humidity. But this new one sucks because the vents are at the bottom. Any dummy can tell you that heat rises, not goes out the bottom. I'd like to have a few words with the designer of that greenhouse...

Is there a way for you to make an open and closeable vents at the top?

[applestar]

I have two of those automatic green house window openers, but I ran out of time and chance to build a properly insulated window to attach it to.

At this point, I’m looking at keeping this structure as tightly wrapped up as I can to NOT lose precious heat. Today in the low 50’s, the internal temp was 70’s when the structure was in full sun. Not expecting much higher than those kinds of temps for a good while.

The window openers and proper windows/vents will be my number one project when things start to heat back up, BUT —Note too that If I had vents that open at 70°F at roof level, the temp at ground level could be much much lower, and the plants will lose their chance to warm up after frigid night temps. So the openers would be disconnected/deactivated for the winter.

For now, all I want to do is get some air movement going and hope fungal disease issues will not become a problem. I did spray everybody with potassium bicarbonate, neem oil, and soap sticker solution a couple of weeks ago as preventative against fungal issues as well as to deal with some pesky aphids.

[applestar]

For yours, easiest way to add a roof level vent is to use heavyweight pvc-safe adhesive film of size you need on both sides of the area where you want the vent to add strength, then attach a frame that sandwiches/secures tightly from both sides and cut the vent hole.

Embellish with insect screen mesh and opening/closing cover and associated mechanism as desired.

I used to have one of those shelves with PVC “greenhouse” cover and made simple vents like that. Really if all you want is to vent out heat, you can just make holes like I did after duct taping from both sides (I taped on a screen mesh and added swiveling flaps to cover when needed)

For walk-in size ones like you have, I’ve seen some complicated carpentry work to build an end wall frame and attach automated greenhouse or RV-type vents on blogs and vlogs.

I have seen some pre-manufactured accessories like that on Amazon if you have the budget. Concentrate on looking for those kinds of hoop and cover “greenhouses” as well as RV and camping goods.

[applestar]

I hurt my elbow about a week ago and then hurt it again when it got a bit better by over doing things, so this project has been pushed back a bit.

But data collection is on going and as you can see, humidity has been hovering in the 90’s (the remote thermometer is set to go red when out of 33°~95°F and 33%~95% RH range.

I think some “freeze dry” effect has been going on, too, but from here on in, the ground is not likely to completely dry out except in terms of freeze. (In other words, any above freezing temp will result in thaw). The humidity does seem to go down when temps go up, however?

[TomatoNut95]

Oh no! Hope it feels better soon! Have a very Merry Christmas!

[Gary350]

Buy a 4 ft long section of sheet metal exhaust pipe for a gas hot water heater. I think those pipes are about 3" or 4" diameter they come in a C shape you need to snap the edges together. Paint the pipe flat black so sun heats up the pipe. Cut hole for pipe in roof of green house so pipe stands vertical. Sun will heat the pipe, heat rises so pipe will make a suction on the green house to try and suck out air. Put 1 of your auto vents down low near the soil so black pipe will suck air through the auto vent. Put a stove pipe damper in the sheet metal pipe to adjust air flow to remove humidity but not all the warm air. When auto vent closes & sun gets dark pipe will not suck out air. Lowe's & Home Depot sell sheet metal duct pipe.

Don't put auto vent on up wind side other wise wind will blow all the heat out of the green house. Don't use 2 auto vents wind will blow in 1 vent and out the other vent with no flow control.