Pump question

[The master plan]

Would a regular circulator pump be big enough for a 600ft 3/4 inch slinky? How about 2 loops of the same for a total of 1200 ft? Can't find much info about geo pumps.... Thanks

[AC_Hacker]

Originally Posted by The master plan

Would a regular circulator pump be big enough for a 600ft 3/4 inch slinky? How about 2 loops of the same for a total of 1200 ft?

1200' too long for 3/4".

A regular circulation pump is like a regular car, there are many options.

First look at the factors that will determine how big and what kind of a pump you will need:

* Length (600 feet in your case)
* Diameter (3/4" in your case)
* Type of fluid (probably water, but will that water have some kind of additive to prevent freezing? If you do have some kind of additive, the percentage should be known... more additive increases viscosity of the fluid)
* Rate of fuid flow desired (the higher the flow, the better the heat transfer, but also the more power required).
* Resistance to flow that your heat exchanger will present to the pump.
* Will your loop and heat exchanger have dissimilar metals that may have corrosion potential? Most pumps, and also the less expensive ones have iron impellers. These are great for iron water loops... if you have any copper or brass in your circuit, you must have a brass or stainless pump impeller or there will be corrosion problems down the road.

So, with this information you could call a pump sales person and he or she would be able to specify the pump you need.

You can also download free software from pump manufacturers that you can run on your computer, that will determine pump size.

In USA, pump sizes are specified in watts or horsepower.

It is handy to know that there are 746 watts per horsepower, so you can compare different pumps.

Without knowing anything at all about your loop, and your ground, etc. I would guess that your loop could be capable of about 1 Ton, but that could vary a lot depending on your local conditions.

The usual loop flow rate is somewhere close to 1.5 g.p.m. per ton.

My uninformed guess is that you would need something less than 1/4 HP (373 watts) for that loop.

I could be wrong about the size, and since it's your money, do some research.


Regards,

-AC_Hacker

[The master plan]

Thanks for the reply...it's 2 separate loops, 600 feet each in the ground about seven feet. They are under were my garage in going to be built. I'll have a insulated slab, so on top the seven feet of earth will be r10 insulation and 4 inches of concrete. I'm hoping the insulated slab will act as several more feet of earth...making the loop act as if it's in the ground deeper. The loop field is about 60 feet long. I know I may have to add more later, I guessed it was around 1 ton of cooling also. For now I plan touse it for cooling the garage only, until I get some more testing and more slinky in the ground. Then I may add a water furance. Pics later...asleep now...lol

[The master plan]

YouTube - ‪DIY geo thermo system‬‏

May still have alittle air in the line? I have a regular water to air heat exchanger for a outside boiler that I will try later and see if I get some cooler temps out of the system. But I want to hook up the second loop before I try that. I will be happy with just being able to cool the garage in the summer. My plan is to have R38 walls, heated slab (2" R10 under slab & up sides) and who knows what up in the attic. The garage will be 24ft by 34ft when completed.

Its been fun and a challenge, but I think this will work out for me well. The pump(Grundfos UP 15-42 B7 Bronze Recirculation Pump) and fan draw 350 watts will running.

Any input from you guys?

[AC_Hacker]

Originally Posted by The master plan

Its been fun and a challenge, but I think this will work out for me well.

Congratulations on your new geothermal air conditioner!

Do you have any details on how you did your ground loop?

It would be very useful to you and everybody else if you kept a journal of temperatures (input, output, ambient, etc). We might all learn something from it.

Again, congratulations on your successful project.

Any thoughts about building a small heat pump for your loop?

Regards,

-AC_Hacker

[The master plan]

I made the ground loops out of 2 600ft rolls of EXCEL 160 IPS 3/4 inch tubing bought from Menards.

I coiled them up with directions found on youtube, making about 32" diameter coils. I don't remember the exact pitch I used for the coils, but laid out, they are about 55' long.

I used duct tape to hold the slinky together and rolled them up into big balls. Then just unrolled them into the trench side by side.

Due to the tight loops and shorter trench, I decided to arrange the pipes coming out of the ground so that when they are hooked up water will flow in opposite directions for each coil. My thought is that the earth will warm or cool from each end of the trench, effectively making the trench/coil longer, rather than running the water into the same end of both coils. I don't know it that theory is correct...but I thought it sounded good after a few beers.



The trench is about 6 feet wide (skid steer bucket width) and about 6 feet deep. We dug down until it got too wet for the skid steer to make it out of the hole. It was dug last fall before all the rain, with the idea to add another 2 coils in another trench about 10 feet away. But I ran out of time and money to get that set done.


This spring we added a foot of gravel above the slinky area and that is where the slab for the garage will be. That will make the slinky coil under at least 7 feet of earth with R10 "250" foam and then 4" on concrete above it. Defiantly below the frost line here in central MN with that set up I believe.


I didn't make a header pipe underground...the pipe is iron pipe size and I didn't want to deal with any connections that could leak underground. The ends of the pipe just come up out of the ground and will go into the building and a header pipe there. At least I can see the leak and fix it then. In hind-site I should of at least insulated the pipe coming up from the depth to the surface, but I don't think 6 feet of pipe will change the water temp much under running conditions.



I'm not sure about making a heat-pump. I've been looking at some videos and your home brew heat pump. I do have a 27,000BTU 220 A/C unit that would be neat to make into one. But I'm more of a mechanic than a appliance person.

While that's an interesting idea, I may just wait a year or two and try and grab a WaterFurance from someone that is upgrading. Craigslist has had several for around $500 within a few hours drive. I doubt I could make one for that, without wreaking at least one or two A/C units in the process.

Besides, I still have the garage to build yet!

As a side note, last winter I hooked the same box, heat exchanger(car radiator) and pump up to a small box I welded out of some steel. Connected 10 feet of steel pipe and set the welded box on a stump I was burning out.

Filled the system up with water and started the fire. We had built a small shelter (4' X 16')out of tarp with clear plastic on the fire side. With the temp 10F outside we rang in the new year with a bunch of friends in 75F room temp with 2 feet of snow outside! Let me tell you it's had to get your friends to come over for a bonfire in January...but they are believers now!!

[AC_Hacker]

Originally Posted by The master plan

Let me tell you it's had to get your friends to come over for a bonfire in January...but they are believers now!!

Great story!

Thanks for the pictures, they really help.

I really do like your attitude... keep up the good work.

Best Regards,

-AC_Hacker

[Xringer]

Those slinky coils look professionally installed! Great job!
I wish that I had those in my backyard!

If I started digging back there, I would hit boulders surrounded by very wet mud,
down at around 16 inches..
The back of our land borders on wetlands. (A swamp)..

[Vern2]

Great stuff! I'm trying to get subscribed to this thread by leaving a short post.

Thanks guys for posting your ground source projects. I'm living is a total electric home in the heat and sun of the desert. All my energy comes from a small solar farm, 9.2K. Short project build at my home link.