Blower help needed for geothermal project

I'm thinking of making a geothermal cooling system for one room in my house. The basic concept is: air blows into underground PVC tube and gets cooled while it is in there. Cooled air gets blown back into room.

So I experimented and put a vertical 3 foot piece of 3/4 inch pvc in the ground. I came back 4 hours later and measured the temperature at the bottom of the vertical PVC at 64F. Great! That's more cool than the current 80F.

I'm thinking of making a circuit of 1 or 2 inch PVC, about 26 foot length, to circulate air. The air from the room will be blown into the pipe by a blower, and exit into the same room, hopefully cooler than it went in. The air will go down into the ground 3 feet, travel out 10 feet, travel back 10 feet, then back up 3 feet into the room. Blower will be located inside the house. Ok, that makes 26 feet the air has to travel.

So now I'm thinking I need a blower to blow this air around. And I'm thinking all this air has weight. How powerful a blower to I need for 20 feet of 1 inch PVC? I was looking at computer blowers (not fans) and was thinking they are not made to blow that much air around.

Do I measure the power of a blower in cubic feet per minute? Or pounds per square inch?

I could use an 110V AC or 12V DC blower. I have a 12V DC adapter I could plug into a wall.

Thanks!

Welcome to CPF!

Here and here are links with information regarding what you're trying.

The idea certainly has merit. I don't mean to rain on your parade, but I don't think a 1" tube moving through 26 feet of soil is going to move enough cool air to have any noticeable cooling effect. You may want to rethink your project on a somewhat larger scale.

Good luck. :buddies:

Also, PVC is a thermal insulator, so if you blow air through a length of pipe it will probably transfer very little heat to the ground. A length of copper or even cast iron pipe would work better, but it would still need to be hundreds of feet long for a decent amount of cooling.

Just build an entire room underground - much more efficient and cool. Take a look at the web site in my Sig line - the 40' Underground room there stays cool all summer. Of course it's a little more pricey than 1" PVC but that PVC won't get you any cooling at all for a house. It takes big pipes and lots of depth in moist soil to get much continuous cooling that way. It was found to not be very efficient or cost effective.

Thanks. That's what I needed to know. I was hoping to get this project done for $200us or less, but it looks like that won't happen. And 1 inch copper pipe, if I can find it locally, costs $1 per foot.

I have a friend who used 600 feet of 4 inch thin plastic pipe (basically drain pipe, complete with holes to let condensation out) and it cooled his whole 3000 sq ft house in the summer.

What's the best way to approach this project?

What is the best material to use for the pipe?

Copper seems expensive. I have a tiny lot and limited budget so an underground room is out of the question.

Thanks again for your input.

you might get more cool air by sucking it out of a large underground cavern, hole, or a deep covered ditch vs. dispersing the heat through the walls of the plastic pipe in a closed circuit.

~5k btu air conditioners can be had for less than $100 USD, are quite sufficient to cool most rooms, and will plug into a normal 120vac outlet. They don't use very much power. If you have window access or can cut a hole in your wall specifically for the air conditioner, this is what I would suggest.

:buddies:

I thought AC compressors and fans use quite a bit more power than a fan alone. Can anyone clarify this?

My house has a whole house AC, but I was trying to save some power by using geothermal to cool a room.

Try a swamp cooler. It's basically a fan blowing through some wet pads.

swamp cooler or that could work...

just remember, air flowing through a PVC tube is BIG TIME static generation.

that being said, Delta makes some fans in their GFB and TFB series that sound ideal (12V and very rare/expensive, but sound right for this...)

Here - found some actually!
They are beasts. but MAN do they have some push...
about 8 times as much as the fart fan in my bathroom....
(keep children and small animals away)

Okay, by the way, i read more carefully over this.

cooling is all about airflow and surface area.
youll want 3" or 4" PVC and a blower like mentioned above.
1" is going to dissapoint you.
...and the GFB is kind of a computer fan, but most standard wall-warts wont power it. not enough amps

and some light reading on PVC and static...

You should be running glycol through PEX in a hole 300 ft deep.

Bonus: geothermal can help heat you house in the winter.

LukeA said:

You should be running glycol through PEX in a hole 300 ft deep.

Bonus: geothermal can help heat you house in the winter.

Click to expand...

for $200 or less like the op was intending?

bulrush said:

I thought AC compressors and fans use quite a bit more power than a fan alone. Can anyone clarify this?

My house has a whole house AC, but I was trying to save some power by using geothermal to cool a room.

Click to expand...

An AC compressor certainly draws more than just a fan, but a single small window AC unit will draw far less than your whole house system.

:buddies:

orionlion82 said:

for $200 or less like the op was intending?

Click to expand...

It's CPF policy to recommend something that costs much more than the OP's budget.

LukeA said:

You should be running glycol through PEX in a hole 300 ft deep.

Bonus: geothermal can help heat you house in the winter.

Click to expand...

You don't really have to go that deep. If you already have a well that is fine. If the lot does'nt have well, we do a ground based loop system that consist of around 1000' of 1-1/4" abs water filled about 4' deep (will vary depending on the areas frost line.

Here's another informative link.