Someone on another forum asked if they could use there lake for there Geothermal system, and it got me to thinking, can you? If you had a lake or even access to the ocean, couldn't you just use that as your source? How does impurities in the water affect the equipment? I know that some ground water is unsuitable for geothernal systems, but why? Isn't the nickel-copper exchanger pretty resistant to corrosion? Obviously you want to have some kind of filter on the intake pipe so you don't suck up fish or other debris, but in theory, is this possible / pratical?

You can put chicken wire mesh or similar mesh ball at the intake pipe, large enough not to feel sucked into the holes.

It depend how muddy and dirt the water contained, some are very clean.

You can reverse the flow from time to time so that it flush out dirts.

Heat exchanger may be used to protect the GSHP equipments but requires more pump and circuits. The heat exchange can be selected depends on water and drits.

Yes you can. Its called a pond loop. Closed system where a stainless steel heat exchanger (SlimJim) or coiled slinky loops are sunk to the bottom of the lake. Open loop would allow too much junk into the heat exchanger.

I know of a system that somebody else installed that's running directly off pond water. Not recommended by any manufacturer I know, but I think the system has been running that way for a couple years. Would obviously require a homeowner checking very frequently for flow / filtration/ etc. General rule for open loops - If you can't drink it, don't run it through the GEO... Sink PE pipe or a SlimJim in your pond.

I'm Specifically refering to Open loop systems only, not closed loops. With a filter to filter out the larger pieces of matter, what harm could anything in the water do to the heat exhanger? Anyone have any idea how long it would take for a heat exchanger to fail with impurities running thru it? I'm wondering with occasional back flushes to clear the pipes/exchanger, would it be economiccaly feasiable to operate a system without digging a well or installing a pipe for a closed loop, just using raw unpurified water.   

Yes, in theory.

As a practical matter such a system would require more attention and maintenance than the average homeowner is willing or able to provide.

I know you can't do an open loop in Lake Michigan (or any tributaries or bays attached). I would guess it would be the same for all of the great lakes. As a matter of fact we could not get a permit to do a closed loop either and found out that you can’t even put a closed loop buried in your yard within 200 feet of the bay or lake. And that 200 feet is from the "high water mark”, typically about 20 to 50 feet from the actual shore line already. We have since moved, but talk about a good heat sink...

By definition a open loop is raw water.  I see no reason why one could not pump out of a given body of water and return it if a constant temprature exists.  If a pond were to be used I would try and get a exchanger that was large in size, and in orifice to overcome small debris, easy in easy out.
  As for life expectancy of the coil....  Who knows try it and report back.

FWIW check into EPA's classification of water used for air conditioning / heat pumps, etc. I think they classify it as "Type V non-contact" water. It is possible that the state or locality, once shown that, might allow use of surface water (or reinjection of well water) for geo use.

Brock when you say "can't do an open loop in Lake MI" do you mean closed loop? Or do you mean can't draw water from?
J

Most ships and some offshore drilling and production rigs use raw water for their heat pumps. Large basket strainers keep out the big stuff but their exchangers are tube-in-shell and need to have the ends removed periodically to rod out the tubes which become coated with all kinds of nasty stuff. Engineer is right in saying the maintenance is more than most homeowners will tolerate.

Great observation, I'm about 20 years past my sailing days, but lots of pleasure craft have these pump and dump systems.
J

When we tried to get a permit to use raw water, an open loop, for a heat pump, that was thrown out without looking. Then we tried a closed loop, passing bay water (from the bay of Green Bay off Lake Michigan) past a heat exchanger, still a no go, next we tried a closed loop, but they wouldn't allow us to put a heat exchanger in or under the water, that one was denied on the rule you can't build or make anything permanent within 200 feet of the high water line. I even tried saying it could be removable if necessary, still no go. The last thing we tried was the standard in ground closed loop in our yard again that was a no, again sighting the 200 foot permanent install rule.

I did point out that dozens of boats I have worked on all had on board heat pumps that could both heat and cool by intake and discharge of bay/lake water, they didn't care. Also many of the local industries including 2 nuclear plants and one coal plant all do this, they didn’t care. Among many of their concerns was that refrigerant used by the system could leak in to the bay, again they totally didn’t understand using a second heat exchanger.

Maybe if some installer that had a lot more time and money than we did could get it past but after spending the money on the permits (you had to pay first before it was approved or denied) and just out right time we gave up.

We have since moved to a location off the Bay, with a nice southern exposure and had lots of space to put in our geothermal field.

Brock, I'm just trying to be clear, you couldn't pump from a well and dump into lake MI?
J

Might cause lake level to rise, flooding shoreline towns.

Y'all got too much government up there

Noah build me an ark....
Don't know of a restriction like this in MI, but that doesn't mean it's not there. I can tell you that I can discharge into any inland waters I like.
We have property on the East coast and due to proximity to lake Huron and Hwy 23 a driveway permit had to be secured not only from the local municipality, but the D.O.T. and the Army Corp of Engineers as well.

Nope you can't "pump and dump" within 200 feet of the Bay. The funny thing is our well was just over 800 feet and the water level in the well was about 85 feet below our basement, about 35 feet below the level of the bay and the water is in the well was bad, lots of iron and tannin in the water. We didn't try to get a closed loop well at the time, not sure if they would have allowed that or not, my guess is not, but who knows.

We did meet some local neighbors about ½ mile from the bay, they have a closed loop under their pond and they had no issues getting permits. Again I think all of our problems were because we were so close to the Bay.

Permits? We don't need no Stinking Permits. I completely gutted and remodeled my bathroom, rewiring half the electrical wiring in my house, add steps onto the back porch, Screened in the porch, installed a french drain, and lots of other projects and never bothered to get a permit for any of them. Some things I would get a permit, like building a house or adding an addition to a house, but townships are just insane if they think I'm going to go file a permit everytime I want to add an electrical outlet to a room. 

If they didn't see you do it, it didnt happen. Permits, your too funny. 

I want to add a Deck to the back of the house, and I may or may not get a permit. I really haven't decided yet.


 

LOL, I honestly thought about it, but I was worried if we ever sold (and we did two years after we tried all this) it wouldn't pass inspection. Then the whole system would have been a waste of money. Our neighbors had done some "landscaping" at the water’s edge and then sold; they ended up paying a $1000+ fine and having to pay to put the escarpment back to the way it was also costing another $5000+. They do fly over with a helicopter and take pictures every spring and fall and look for any visible changes from the previous picture.

Again this is part of why we moved, the view was hard to beat though...

Most of the issues with the great lakes are going to be federal issues (army corps of egineers). So that certainly explains the lack of common sense.
J