Geothermal water temp is HIGH

[jjohns]

we are homeowners with an 18 year old ground loop system . Great so far. last summer, water in loop got to 99*. right now, it's up to 97* and it's only been hot outside for two weeks! units are not cooling well. Can a residue build up in the pipes that should be flushed out for better waterflow ?

last summer contractor installed a portable cooling tower for a month to cool the ground water he piped thru it. that helped but it's happening again.

any ideas ? This forum looks like there are some great people on it !

thanks!!

[daniel_110]

is the loop water treated, it sounds as if you have a build up inside the tubes preventing the transfer of heat. if not treated youll have to flush the earthloop with a chemical to clean them and then treat the make up water after.

[BobbyBJr]

Where are you located? Sounds like possibly there's air in the loop or the loop is undersized for your load, or possibly a pump has lost some capacity. It's possible there could be buildup, but rare on a sealed system, that is, if it's truly sealed.

Bobby

[durapump]

Hi there, nice to see someone else new on here!
What is said above sounds right to me too - possibly a build up affecting the pump. Additional tests are necessary to accurately diagnose the source of the problem with this as it's hard to tell exactly what it is without seeing it etc. Hopefully you can get it solved! Keep us updated.

[crispE]

Im assuming this system worked perfectly for years and years without getting the ground loop to near 100 degrees.
Things to check
1. Verify the amount of water flow going through the heat exchanger. If the waterflow is not high enough to cause turbulence in the water, can you say reynolds number, you will have laminar flow which will not transfer heat very well in the ground loop itself.
2. Is the compressor starting to fail or not working efficiently anymore. 18 years old im assuming its a reciprocating compressor and as the rings and pistons wear it will generate much more heat as it runs, this heat is then transfered to the condenser, or the ground loop which could cause the higher temperatures by increasing the heat load.
3. Make sure the refrigerant is charged properly. Everything else could be perfect still and just small leak or txv has failed.
This is definately a job for someone who is experienced with working on geothermal systems.
My guess is number 3, ive seen many systems operate 100% capacity at 115 EWT, but that is on the high end of the spectrum and definately lowers the COP, or efficiency as some may say.