Hi folks! I usually hang out on the daylily forum but I have lurked here for a while as my husband and I set up our high tunnel. There's a lot to learn and I'm not mechanically-minded. I'm having a tough time figuring out the best place to buy the ventilation items and wondered if any of you would have ideas.

Our gothic high tunnel is 30' wide by 72' long, 6' side walls and 14' at the highest point. We have set up the steel frame and are working next on wood-framed end walls. Our rig has roll-up 16' openings on each end and crank-roll sides. Single 6 mil poly covering. We are in East Tennessee and the site is a bit protected, so wind and extreme temperatures aren't too much of a concern.

I figure I need to move about 16,000 CFM. One large and powerful exhaust fan or a couple smaller ones? Options for fan speed seem helpful. A couple shutters, maybe mechanized, maybe an extra, smaller gable shutter up high? Trying to save but don't want to waste money by making limiting choices on the front end. We paid so much freight getting the main GH shipped that I'm hoping to pick up accessories or find free shipping. Any guidance re vendors or general ideas would be very much appreciated.

Wow, that's quite an undertaking! I usually start at the Greenhouse Megastore.

Good luck! Post progress photos please.

Thanks, Daisy. I like the free shipping aspect but prices seemed a bit high. I'll take another look. Yes, it's a big structure to erect and space to manage but we have big plans too!

I have purchased several items from J&D manufacturing and have been pleased. Not cheap, but good quality. I used to buy cheaper, but you get what you pay for, and cheaper equipment just doesn't last.

Thanks, Jim. Yes, you're right- you do get what you pay for. I don't want to waste funds and am wrestling with my thrifty side here. But if I know it's the right product and a GOOD product, it's not a waste. I was eying the Typhoon- it takes a powerful fan to move enough air...

Or a series of fans. The biggest problem in greenhouses is dead air spots.

Justine. I am not that familiar with Typhoon, but it looks like a good fan. It is also a J&D Manufacturing product. I know from experience that J&D only sells good quality equipment. A number of years back I was a reseller for them, and my customers were always happy with any J&D products they purchased. You can also contact them. I always found them helpful when I had questions or was sizing a piece of equipment.

I've bought ventilation stuff from Charley's Greenhouse and Tek Supply: thermally-activated louver intake vents and an exhaust fan. But I built a row of clerestory roof exhaust vents with thermal pistons, to take advantage of the prevailing winds, which are so effective that the electric exhaust fan seldom gets used.



As far as dead air problems, having multiple low vents is probably the best approach.

subarctic said:
As far as dead air problems, having multiple low vents is probably the best approach.

I have multiple low vents and roof vents. The dead air occurs on the wall above the lower vents. The fix is to aim the fans slightly toward the wall.

Interesting! Chip, are those ridge vents? And what are the black things against the back wall? Very cool that your system works so well! I wish we had a ridge vent option but the poly doesn't easily play that way in the design of ours and the material on hand.

So, are we talking about air intake vents/louvers and particularly dead air above those? And circulation fans inside the greenhouse to remedy areas of low air movement? With possibly a single exhaust fan on one end, I can see that air would need some disturbing or it would just cruise directly over and up to the exhaust fan level.

Thanks for the encouragement, Jim. I bet you did a great job serving folks. I'm nervous about sales guys talking fancy to me and trying to upsell. Sort of like a trip for a "free" oil change at the car dealership. "M'aam, your truck seems in pretty good shape except the diagnostic shows (weird problem) with the (truck part that I have never heard of). We recommend that you (let us do this unintelligible process, for a chunk of change)" It gets confusing pretty quickly.

Hembrain said:Interesting! Chip, are those ridge vents? And what are the black things against the back wall?

I designed it with clerestory vents, oriented across the prevailing wind (strong, here) to take advantage of the pressure difference and draw hot air out. They were supposed to be twice as high, but my contractor friend said the main roofbeam had to be larger to take the snow load. They still work fine.


The black things are large plastic water tanks, filled with the garden hose, which serve as passive heatsinks and also as the water source (so, no plumbing).

Very cool and thoughtful design, Chip. And beautiful surroundings.