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EDIT: Talked to local HVAC company and they had put in a similar system a few years ago.  Turns out the superfine sand/clay clogs the heat pump exchanger after a while.  
So since I'm not wanting to have a high maintenance system that would be a liability to whoever gets it next I'll go with high efficiency air to air.  Got the perfect spot for it, in the shade and just outside the breaker box.

Looking forward to more comfortable working conditions!

Thanks for the help.
______________________________original post:

I've decided I need to put some HVAC in my shop.  I've got a good creek 200' away -- never freezes, never runs dry, just sometimes a bit muddy (fine sand/clay) and I'd like to use it for the source.  Plan is to put submersible pump in creek to pump water up to shop (8'lift) then run it through the heat exchanger and drain it back to the creek.   Probably need some kind of filter in the mix.

Shop is 32'x48' with 12' eaves. Well insulated (fiberglass walls, spray foam roof, insulated doors and double-pane windows) and barrel stove for back-up/auxiliary heat and scrap control.

Anyone have any experience with something like that?  

central KY, mild winters but I tried working down there this afternoon and fingers gave out too soon in the 40-degree temps.  

With the water-source and cheap electricity it shouldn't cost much to make it a pleasant place to work.

We tried some back in the 70's using a 1/4 to 1/2 acre ponds back then they would freeze the pond down to below the drinking water inlet was but until that happened they worked very well.

Some geothermal systems work that way, and I suspect you can do it. I'll be interested to see how it works out. I am wondering if that much distance will cause a heat loss in the water making the whole system a little less workable. You may have to insulate the transfer piping.

You could probably run a mini-split heat pump cheaper, more efficiently with a much greater heat exchange rate than running a pump and blower.

A few installations were done semi-locally several years ago using lakes or big ponds. But in the ones I know of, the placed the heat exchanger in the water source and pumped an antifreeze/water mix rather than lake water. I have no info on long term success but initial reports were positive.

A few installations were done semi-locally several years ago using lakes or big ponds. But in the ones I know of, the placed the heat exchanger in the water source and pumped an antifreeze/water mix rather than lake water. I have no info on long term success but initial reports were positive.

(02-27-2022, 09:22 AM)Snipe Hunter Wrote: [ -> ]You could probably run a mini-split heat pump cheaper, more efficiently with a much greater heat exchange rate than running a pump and blower.

I agree.  As much as I like the idea of "free" energy, I don't think it will really pay off.  The complexity alone makes it not worth it to me.  I know people have heated their houses from ponds and lakes.  I'm curious how they feel about that years on.  The geothermal companies around here always used the two well system, which is a similar concept.  Not sure if they would permit that nowadays.

I always wanted geothermal, but I'm going with minisplit for the house if I can get anyone to put it in.  It's next on the list. Kentucky seems like the ideal place for minisplits.

Plan is to pump water into a 55-gal "settling tank" in the shop, then into the heat exchanger.  Water stays about 50 degrees year-round.

May have too much space for a mini-split.

still researching!

Our new addition has a Mini-split heat pump. 440 sq ft and it does fine. You can install several evaporator coils (indoor part) off of one condenser/compressor unit which can heat and cool about 1500 sq ft. You can also do through wall heat pumps. Like a window unit but not in a window.

(02-27-2022, 12:29 PM)Wild Turkey Wrote: [ -> ]Plan is to pump water into a 55-gal "settling tank" in the shop, then into the heat exchanger.  Water stays about 50 degrees year-round.

May have too much space for a mini-split.

still researching!

The "settling tank" should be a sealed tank (similar to a water heater) to take advantage of the siphoning effect of the water returning to the creek. It significantly reduces the power for the pumping.  If you could get the discharge low enough to offset the friction in the pipe, a pump might not even be required. You could help the flow with a funnel on the inlet and a venturi on the return. The evaporator (and/or condenser with a reversing valve) could be a coil of copper tube in the tank. The only difference between this and "direct exchange geothermal" (which is very efficient) is that you moved the thermal mass closer to the compressor. With a little thought it could be self-cleaning.

If you're up for a project and are interested in learning more about building it yourself, check out https://ecorenovator.org/forum/ There are knowledgeable, helpful people there too; just like Woodnet.

You might even be able to tap enough energy from the creek to power the whole system. I'd love to keep my shop at 72* year round for free!