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tinkerer
29-07-2008, 02:17 AM
Hello, this is my first post. I'm no pro, just a guy that kept ACs going. What I would like to do is to cut into my outside condenser coil and run tubing into the house to a water source condenser and then back outside so I can have a geothermal setup. I'm retired on a fixed income and would need to make my own condenser from tubing inside tubing. Here in Nebraska the extremes are -25 to +105 f. I already have a well and also a small pond to dump to. The heat pump is a 3 ton unit. Is it worth it and feasible?

yangchenchen
30-07-2008, 09:41 AM
I am an geothermal heat pump unit disign engineer, to my experience ,it is feasible.

taz24
30-07-2008, 01:19 PM
Hello, this is my first post. I'm no pro, just a guy that kept ACs going. What I would like to do is to cut into my outside condenser coil and run tubing into the house to a water source condenser and then back outside so I can have a geothermal setup. I'm retired on a fixed income and would need to make my own condenser from tubing inside tubing. Here in Nebraska the extremes are -25 to +105 f. I already have a well and also a small pond to dump to. The heat pump is a 3 ton unit. Is it worth it and feasible?


Yes you will be able to do it.
Think about filtering this supply water.
A pipe within a pipe would do the job you might need to experiment with the size to start with.
I would fit service valves into the system to ease any future work that you may need to do.

If you use 1/2 inch inside 7/8 or 5/8 inch what you need to do is thread the 1/2 inch inside the larger all the way and braze in the fittings for the water to one end only, while the pipes are still straight.
Then coil from the fixed end one turn or full loop, then try to push the 1/2 inch back into the 5/8 from the free end and that will stop the 1/2 from being only on the inside of the internal 5/8 (pipes comercialy designed have spacers inside the seperate the two pipes to allow the water to circulate fully around the refrigerant pipe).

Continue to coil the pipes as tight as need be (coil around somthing round and about a foot or 18inch diamiter. When you get to the end leave the water side free but conect the refrigerant to the system.

Conect a hose pipe with tap water from your kitchen and just let the water flow to waste to start. Run the system and test that you have the right tempreture exchange if you have too much then you can cut the end of the water pipe by a foot or so.
Keep testing till you get the correct settings and when you are happy remove it all and braze fit all the conections to finish it.

Why do you need to bring it inside? Are you afraid the water may freeze in the winter?

Any more questions feel free to ask.

Cheers taz.

The MG Pony
31-07-2008, 03:36 AM
Keep an eye on ebay, you can find some good deals on there for ready made rigs, a friend told me there is a 3 ton coaxial exchanger on there now, worth to see if it is still there!

imad8
08-08-2008, 09:10 PM
I am an geothermal heat pump unit disign engineer, to my experience ,it is feasible.
although it is not accurate to use the term ''geothermal'' for well- source heat pump,i think u can enhance the COP but u would not reduce the cost.

cleanNcold
02-10-2008, 01:45 AM
Rather than go through all of that and suffer in efficiency, why not go to packless.com and just buy a heat pump condenser coil?

EDDC
04-10-2008, 05:34 PM
how about the plate exchangers listed on ebay? claims are good to 400psi & usable on *****. i bought the smallest for use on an approx 3000btu water source heater ($55 total). project is listed elsewhere & is not completed yet.
regards;
eddc

chemi-cool
04-10-2008, 07:31 PM
I would also go for PHE,

here are some for great prices,

http://shop.ebay.com/items/_W0QQ_fromZR46?_nkw=plate+heat+exchanger&_sacat=0&_fromfsb=&_trksid=m270.l1311&_odkw=water+heat+exchanger&_osacat=0

cleanNcold
08-10-2008, 04:58 AM
Although I agree that there is no better exchanger than a plate, I caution that in this situation it is very important to have proper controls to prevent freezup of the exchanger. A pressure switch and/or cold control are not enough for protection. I would use an adjustable low pressure control, a freezstat, and a water flow switch to protect the exchanger. I have seen many heat pump plates ruptured and if that happens, everything is junk. Compressor, reversing valve, line set, evap. coil, everything.

cleanNcold
08-10-2008, 05:02 AM
By the way, imad8, why is it not accurate to call an open loop heat pump a geothermal? I may be not understanding what you meant.

JoB
12-11-2008, 09:27 PM
Tinkerer,

I just stumbled on this forum and am wondering if you have gotten any answers that helped you convert your airsource heat pump to watersource. I am thinking of doing the same thing. I installed a new 3-1/2 ton airsource heatpump last summer when the old a/c wasn't doing the job anymore. I didn't thoroughly investigate or would have put in a watersource then. Now I don't want to take out a almost new hp that works very well down to 15F when it would most likely do all I need if it was working with 50F water.
I also have a well and a place to dump the water.
In MN it would have to give me all 42,000 btu's when it is gets below zero. I'm heating a 2800sqf log home.
I have been thinking of cutting off the outside coil and replacing it with a heat exchanger made with copper refrigerant tubing inside a larger PEX water tube of the correct length would be easy to make and should work with sufficient well water flow. It should also be easy to clean the iron fouling with chemical (iron out) occasionally. I would eliminate the outside coil entirely and move everything inside the basement if it works. I don't know what the length should be, but seeing pictures of manufactured units the don't look to be very long. A homemade exchanger would not be as space efficient using regular copper tubing instead of the spiral type but I think a 25' coil would be very inexpensive to make.

nh3wizard
12-11-2008, 10:15 PM
It looks like tinkerer hasnt been around since August 16th 2008:eek: I guess he doenst care:mad:

JoB
12-11-2008, 11:19 PM
nh3wizard,

Have you been to Joel's Pizza Palace in Valrico? I heard they have the best food in town.

nh3wizard
13-11-2008, 03:52 PM
nh3wizard,

Have you been to Joel's Pizza Palace in Valrico? I heard they have the best food in town.

Never heard of them, but know you have my curiosity up and I will have to check them out.:off topic:

The MG Pony
15-11-2008, 08:22 PM
Comercial Hxs are riffled inside the refrigerant side.