geothermal pond loop?

[Chilly807]

Thanks Chilly,
I just spoke to a man who sells the heat pumps. He was nice enough to give me some good time and answered many questions. He's been using a well-dump system for the last 30 years and my well will work with that system. Not sure that I want to do a dump even though I have 20+ gallons per minute flow, I like the idea of running it back to the aquifer. The easiest set up is the dump though and it's very efficient at 175 feet down it's just about right for my 2 ton needs. The dump means I'll be putting about 180 gallons an hour into the dry well, probably a lot less though as the pump will probably only run 15 minutes per hour on most days. Let's see, that comes out to 180/4 or 45 gph. I'll have to think about it.
Rob

Be careful of your water quality, if it's hard at all it'll dramatically shorten the life of your heat exchanger. With a closed loop system you have much better control over the water in it.

Sean

 

[Rob-D]

Be careful of your water quality, if it's hard at all it'll dramatically shorten the life of your heat exchanger. With a closed loop system you have much better control over the water in it.

Sean

Thanks, I'll check the water. I think Hydron has limits on their site.
Rob

 

[pat32rf]

The first 450 feet of our 500' loop is only in about 4-5 feet of water, then it drops down to 10-15' for the final 50' before it loops back towards the house. Two ton unit.
Our water is VERY soft but acidic so a closed loop was a no brainer.
Our installer/supplier had been involved with some "direct exchange" units many years ago but none of the copper has lasted longer than 10-15 years due to the acid soil conditions.
I also looked into a stainless steel plate heat exchanger but didn't have enough depth of water.

 

[buckeyefarmer]

Fluffed coils are known as slinkies. Most horizontal installs use slinkies, as it takes less ground area for a relatively small increase in the amount of pipe. Almost all pond installs also use closed loops, because of water issues. Most people who do pump and dump do it because they sit on a very good aquifer.

 

[Redneck in training]

There are also vertical closed systems. My brother sells the equipment in Europe. They are popular because most houses sit on small parcels. They are tricky to design correctly due to the fact that wells are expensive. There is a fine line between overkill (costly) and proper function. He told me that they design them such a way that the well will be about halfway frozen at the end of the heating season.

 

[Rob-D]

Fluffed coils are known as slinkies. Most horizontal installs use slinkies, as it takes less ground area for a relatively small increase in the amount of pipe. Almost all pond installs also use closed loops, because of water issues. Most people who do pump and dump do it because they sit on a very good aquifer.

I do, 20+ gpm. The driller told me I could easily have 50 gpm but because no one uses that much they just call it 20+. I can dump it into my stream which is about 25 feet away from it. The trouble is that i have a lot of iron and if I remember my PH is high.
The beauty of well dumps is that you get warmer water, usually around 55F as opposed to 42F for ground loops.

Rob

 

[20 20]

I didn't notice the thread was still active{my bad} thanks for all the advice. From everything I'm learning{gathering} it seems that inground{closed loop} will be my best bet. I also read that geothermo works best in clay type soils below frost grade{7'+ down for this area}. I curse this clay soil of ours but maybe it isn't such a bad thing after all . My next biggest issue will be rocks{boulders}, we grow them in this area.

Are there any sites that explain the pumps/electronics of the systems?

 

[Rob-D]

I didn't notice the thread was still active{my bad} thanks for all the advice. From everything I'm learning{gathering} it seems that inground{closed loop} will be my best bet. I also read that geothermo works best in clay type soils below frost grade{7'+ down for this area}. I curse this clay soil of ours but maybe it isn't such a bad thing after all . My next biggest issue will be rocks{boulders}, we grow them in this area.

Are there any sites that explain the pumps/electronics of the systems?

20 20,
I have the same soil (two rocks for every dirt) and my top soil ends at about 24" with clay below that. I was thinking about digging a hole and burying a temperature sensor and putting one in my pond too. I have a geothermal installer comingout tomorrow, I'll post his professional opinion after we talk.
Rob

 

[20 20]

Thanks Rob-D

 

[eepete]

Here's a shot of the pump that was installed with my system. This is for 8 tons of cooling. I have a similar pump center for a 3 ton, and the only difference is it has only one pump on it.

The brass circles on the right are valves that come out on sides (well, top and bottom in this pix) that allow the water to be pumped in, air pumped out, and allow the methanol to be added to the system (as an antifreeze).

These are 240V pumps. They are labeled as drawing 1.8 amps each, listed as 377 Watts (yeah, the math doesn't quite work out....). You can also see the valves so you can work either the heat pump or the field independently.

IIRC, the system is pressurized at about 50 PSI. The two lines go outside, and the manifold pit is buried. It's clear from various posts that how and where the manifold is done varies greatly, and it's not too hard to figure out the pros and cons of each approach.

The wires above are not related, they go to the outbuilding. You can see the bottom of the gas tubes (just like telephone company uses) at the top of the picture. It was a big win running 5 3" pipes for 80 feet so they were way outside the perimeter of the house. It let this field be installed after construction, and let me get things to the outbuilding. I also ran a 3" electrical conduit. I mention this because nature abhors a vacuum, so while the ground is open thing about if there is anything else you want to put in there.

Pete