Greenhouse inflator fan

Where the air hose brings air to the blower

Winter is one of those times around the farm where you discover those things you thought you did… but didn’t.  In the case of the greenhouse everything has been humming along just fine since last spring when we completed the construction…  the only thing I think we didn’t do was drill one small hole in the end to provide a fresh air supply to the inflator.

Our hoophouse / hightunnel / greenhouse hybrid is just that - a hybrid.  We designed the structure and bent the hoops ourself and don’t heat the structure…  but we also had to make things more robust than just a standard hoop house because of the stormy winds we get.  So, we opted to use a greenhouse inflator.

The inflator / blower

The inflator is a small fan that is supposed to draw air from outside the structure and inflate the space between 2 layers of plastic (like a ziplock bag).  The plastic is then taunt and the wind can’t grab and rip it off.  The added benefit of this kind of structure is the fact that the layer of air acts as a really good insulator helping to keep the passive solar heat the structure gains during the day from just disappearing so quickly at night.  The results have been great - when it’s 10F outside in the morning the inside of the hoop is still just above freezing.

So, back to the point here…  when we built the greenhouse I never put the inflator air source outside like I should have.  It worked fine (the structure isn’t exactly air tight) but it was pulling in very humid greenhouse air.  I don’t know if that would ultimately matter but I do know the installation instructions said to pull in fresh outside air to inflate the layers of plastic.  And who am I to not follow instructions?!

Where the fresh air comes in for the inflator

So with a 1 1/4” hole saw bit I poked a hole in the T-111 siding and mounted the inflator air source out there.  Who knows if it will ever matter…  but I guess NOW I can say “the greenhouse is done”!

Well, at least until I find something else that didn’t get finished.

Comments

[lawnphysics]

What size (CFM) inflation fan did you use? Also, what do they call the round plastic insert you use to attach the fan to the plastic itself?

[Andy]

Here's the inflator we have - http://www.farmtek.com/farm/supplies/prod1;;pgqh1095_110094.html (all the specs are in the pdf). And the plastic thing (the white thing) is a deflector. You don't want the fan blowing on the plastic directly or it will wear it out in a year or so.

I also have a one of these - http://www.farmtek.com/farm/supplies/ProductDisplay?catalogId=10052&productId=45122

So I don't know exactly what we are pulling in terms of total CFM - but it's nowhere near the max. The goal is to keep the plastic inflated without stretching it. Hotter days need less pressure or the plastic will stretch under less load... and when it's windy you want it inflated a little tighter so there's nowhere for the wind to ripple the plastic, grap and tear things.

Some people install a manometer that measures the pressure between the layers of plastic... I have just been guessing and so far things have been fine.