I should have just searched the forums! The answer was easily found.

A large swamp cooler inside? That sounds like a sauna, 120F and 90% humidity.

For effective cooling you need a wet wall and exhaust fans on opposite end.

My inflation fan uses outside air.

Of course you want to use inside air, if you fill up your insulating double layer with outside air constantly it will be like having a single layer of film.

Maybe a little slower because teh convection within the bubble is less than outside. But still. It's part of the conditioned envelope, keep it inside.

Fruitnut, fortunately I have not had the experience you describe using the swamp cooler in another greenhouse. When the swamp cooler is on there has been plenty of venting and I've been able to keep the temp at 95 or below when its been as high as 115 outside. I think the venting has been the key to this.

Golden, originally I was thinking the same as you but my research indicates that using outside air is better because adding humidity between the poly layers could decrease the life expectancy of the poly. Something else that made sense to me was that once the inflation is completed, there isn't going to be much exchange of the layer of air between the poly layers. I'm still open to ideas but as of now I'm going with the outside air. I am going to add a filter to the outside air intake though because when it gets windy here it kicks up a lot of dust which dust I also don't want in between the poly layers.

What do people generally use for their inflation? I see various inflation kits all over the internet ranging from $113 to around $200. Any suggestions as to a good kit to get?

Most greenhouse manufacturers recommend outside air, for the reasons mrlupin mentions.

“We
recommend using outside air for inflating double layer poly because it has less
moisture and less chemicals which can come in contact with the film”

http://www.klerksusa.com/a/docs/GreenhouseInstallationGuide.pdf

Shows what I know.

I know the specialLists recommend outside air but it never made sense to me and I've used inside air for all of my structures with no I'll effects. I've had my first GH inflated that way for 14 years before needing to replace films.

The biggest reason for choosing inside is b/c then the inflation fan is inside, out of the weather. I can't imagine keeping fan and electrical aspects dry if the fan is located outside. Sliding snow could cause the fan to even move out of position.

I used an old bathroom ceiling fan for years but recently I have acquired 2-3 backup fans at various auctions. All of my exhaust fans and intake louvers are cheap used units that have given me many years of reliable use. For some reason most circulation fans I have were purchased new although I just purchased 7 used box fans which come in handy occasionally.

Inflation fans using outside air are located inside the greenhouse. An intake tube is attached to the fan and run just outside of the greenhouse.

You can reduce the running cost of the inflation blower by a fair percentage using this technique.
http://www.sunnyjohn.com/photos/devices_tools/dt_inflate_blower/index.htm

Hex that is a dead link. Did you put it on Youtube by chance?