BIG mid vent – thoughts / suggestions / concerns?

[Kyle]

I thought I’d share my BIG vent for my 9×9 mid. I was inspired by a previous post on BPL forums… Its a little over 23 inches tall, from top to bottom, about 28 inches wide at the base, and it raises 9 inches at its highest point (it even has a cat curve =P, cuz why not?). I was wondering why this isn’t done more, besides it being a pain in the you-know-what. Maybe it was all for not… Anywho – I’d love some input!

-K

 

[Mario Caceres]

That’s a big vent.  I wonder which is better 1) to have more smaller vents closer to the top or 2) fewer larger vents.

Warm air goes up, vents allow it to escape hence reducing condensation problems.  I would think the base of your vent is were most of the warm air escape, but there will be some warm air that doesn’t make it out and continues to raise to the peak of your mid remaining trapped there (again warm air goes up not down).

If you have a HUGE vent like yours, the amount of air that remains above the bottom of your vent line is quite large.  It will create condensation in that area which will eventually drip down the walls of your shelter.

Now lets assume that you instead of having 1 large vent of 28″ base on the front of your mid , you have 4 small vents of 7″ base each on each side of your mid.  I think the “escape line” you would be providing to the warm air would be the same (28″), but the area above the bottom of your vents would be quite smaller hence reducing the amount of warm air that will remain trapped and its condensation problem.

If you are set with your larger vent, perhaps where you have the catenary line on the vent hood you can have a small waterproof zipper,  which you will keep open when is not raining and close (forming the hood) when it rains.  In that case you would not only have 28″ of venting, but the whole triangular area of your vent will allow the uprising warm air to escape.

[Kyle]

good point. i guess i was (and still am) hoping that there will be some sort of magical atmospheric differentials that will help out with air circulation… a person can dream =P

[Mario Caceres]

Kyle, it probably will work out OK, I’m just thinking out loud from the way I understand things work.  i don’t have any technical expertise on these matters.  A while ago I made a hexagonal mid, it’s got 3 vents (unfortunately I have my gear in storage so I can not give you exact dimensions for comparison)  but probably the base of each vent is about 5″-6″.  I always pitch the mid 2″-4″ above the ground to help with ventilation / airflow and normally condensation has not been an issue.

[Kyle]

With 3 vents I hope there’d be no condensation issues! I’ll be honest – I went with 1 because it seemed like less work =P

[Mario Caceres]

Kyle, perhaps if in addition to your large vent in the front (door) panel you can add a smaller vent on the opposite panel. That way your large vent on the door may also work as an “intake” to push out thru the smaller (and higher) vent on the opposite side the warm air trapped on the peak.   It’s probably easier to add that vent before you assemble your pyramid tent.   On the other hand the “Zipper in the middle of the vent hood” option I mentioned before is something you probably can do afterwards if you find out your large vent is not working as you hoped.

[Kyle]

i really like the zipper idea – i think i’ll keep that in my back pocket in case things don’t work out. its too late in the game for me to put holes in the opposite side wall. i could also put another smaller vent, in the bigger vent shield, just to let out some of that trapped hot air, but that may just be crazy…

[Mario Caceres]

Maybe just try to keep the vent hood up against the mid wall (not out) by tie-ing it to the top of the mid.  That way you would be able to increase the size of the “effective escape area” for uprising warm air when is not raining.

[Kyle]

perfect! – it’ll be interesting to see how that works compared to full open…

[Ben Wortman]

I like big vents!

One possible change to the a large vent I put on a mid is to have the hood totally removable.  That way in hot weather there would not be a “pocket” of hot air and the heat can just flow out the top.

Regardless, I stand by the thought that a mid without a vent system is just a sweat lodge or greenhouse in direct sunlight.  Way too uncomfortable for me.  I have made both and the difference is dramatic.

 

Ben

 

[Kyle]

You are the guy who inspired this vent, Ben! Thanks for posting that mid of yours, it’s what got me started down this path… I think for the super hot days, I’ll just be opening up the top portion of the zipper. As I used a 2-way, and will have a nice lil bug net inside to boot. Thanks again!!!

[Ben Wortman]

Sweet!

I am trying to decide if a netting door or a stand alone net tent inside of the mid is the way to go.  Both have different advantages, but I am leaning toward the net door for mosquito season.

Good luck with the Mid!

 

Ben

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