Plumbing challenge?

Here's what I'd like to do:
Run well water through a geothermal heat exchanger and then discharge the same water into the yard and eventually into a pond.
I prefer not to go underground and below frost depth with discharge pipe.
I would like to simply have water discharge above ground. How can this be done without discharge pipe freezing?
My first thought is a antisyphon device similar to what's on outdoor spigots.
Discharge pipe is 1".
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franz fripplfrappl wrote:

If it gets cold enough, it'll freeze. What you propose is basically the same as a fountain or backyard water feature. The running water will slow down the freezing action, but the outlet hole will keep getting smaller, and eventually get blocked. The pool dealer down the road has a fountain out front, and dumps blue dye in the water each fall when it starts getting cold. After a couple weeks, he has a huge ice sculpture, and no more running water. Even if you can keep the outlet and exposed pipe from freezing solid and splitting, the water WILL stop flowing at some point, and your yard will be a mass of ice.
Just out of curiosity, what are you trying to do with the water? And what is the heat exchanger for? Ground water is going to be at the same temp as the below-frostline dirt in the first place, isn't it? Or do you have a hot spring under your house?
aem sends, curiously....
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On Mon, 18 Feb 2008 18:42:33 +0000, aemeijers wrote:

Thanks.
We're using well water in an open loop geothermal installation. Water goes through a heat exchanger which transfers it to fluid circulating through radiant tubing. Will also heat domestic water with the same. Once heat is extracted from well water, it has nowhere to go than into the pond.
I know, I know, it seems incredible to extract heat from something cold, but it does work. I once had a heat pump water heater and it did just that. It took ambient air temperature, extracted the heat and transferred the heat to the water. The downside of this system was it also chilled the basement air. On the other hand, in summer it cooled the basement as well as dehumidified.
Geothermal is the way to go for heat.
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wrote:

Ah, ha. I thought you were trying to warm the well water. Letting it then cool off seemed strange.

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wrote:

If you really think water is valuable you should be putting it back where it came from after you have sucked out some of the heat.
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On Mon, 18 Feb 2008 14:00:46 -0500, gfretwell wrote:

Thanks for opinion. Unfortunately DNR does not permit open loop geothermal systems which go from one well and discharge into another. This makes sense for conserving water but DNR is afraid of contamination. Can't figure out how a "sealed" well system can get contaminated.
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You can't? You said in another post: "We're using well water in an open loop geothermal installation. Water goes through a heat exchanger which transfers it to fluid circulating through radiant tubing."
What is circulating through the radiant tubing? Eventually, that water or water plus chemical will leak into the system when the heat exchanger goes bad. It may be one year, five years, twenty five years, but it will happen.
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When the exterior air temperature is below freezing, will the discharge be running constantly? And what is the discharge temperature of the water?
If the water is running constantly, then depending on the discharge temperature, flow rate and heat loss of the discharge pipe, the water won't freeze. Unlike a circulating pond, which has no outside source of heat except the pump motor, this discharge pipe will constantly be fed with warmer than ambient water.
Even if the water flow isn't constant, it is possible that if you empty the pipe when the discharge stops, then whatever ice forms near the outlet will be melt by the next discharge cycle. Again, it depends on the balance of heat flows.
Cheers, Wayne
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Discharging water to the yard in freezing weather sounds like a potential problem. I visualize ice dams, backups into basements, kids and dogs sliding on the ice into the pond and they system backing up leaving you with no heat.
How much water are you talking about?
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On Mon, 18 Feb 2008 18:56:02 -0500, David L. Martel wrote:

The pond is 200 feet from building. If it works, I'd like to discharge water into a small water feature/stream which eventually leads to pond. Cheaper than trenching and laying pipe.
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I assume you intend to run a pipe all the way to the pond above ground.
If the pipe does freeze it likely can't be thawed until spring so you would need a backup system or you would have no geothermal heat or a huge mess wherever the discharge ended up. Potential for very expensive damage both within the house and outside of the house is very high without a backup system. Note backup must be totally independent of the first system or it would just fail same as the first system. Designing for cold system water flow is a huge engineering challenge. A foolproof system would cost a lot more than just burying the pipe in the first place.
You would have to insulate the pipe no matter what or it would freeze if you get cold like we get.
Could you run the flow into a pipe that was large enough to flow under gravity alone? 3 or 4 inch should do it if you have a reasonable slope. Design this so that it would drain empty between cycles and the heat trace could be routed into the pipe from the top - maybe from the top of a tee that was a few feet long to prevent overflow. Then the heat trace would only have to heat the inside of the pipe and not the outside air.
The geothermal system lowers the temp of the discharge water as it sucks the heat out of it and so you have very little heat left in the discharge. The installer set my geothermal system flows so that the discharge water was at 38 F which gives a bit of safety factor against freezing within the heat exchanger. It leaves a very poor safety factor against freezing in a surface discharge pipe.
If the water cools to freezing temp before it reaches the end of the pipe it becomes frazil ice - small super-cooled ice crystals - that consolidate into solid ice almost instantly and in difficult to predict locations. the system could seem to run fine for a while and then on a cold night it could instantly solidify.
Use PE pipe because it won't split if it does freeze.
Your perfect solution, but very expensive is insulated PE pipe that has heat trace inside the insulation already and could run a a pressure discharge. Last time I looked, many years ago, the cost was $5 to $15 per foot. There are many water systems up north using this pipe and most are barely buried or are buried within permafrost.
How would you keep the pond from overflowing or the ice buildup from getting out of hand?
It gets very cold up here in central Canada and I have seen some water pipes that were left running all winter to keep them from freezing. Only works if the huge ice pile that results can be located where it does no harm. very expensive to waste that much water. In your case running the well pump all winter would only cost a couple of hundred dollars extra over letting it just cycle when the house thermostat calls for heat.
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