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Old 01-17-2011, 08:14 AM   #1
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Geothermal closed loop


I have a geothermal closed loop sytem that has glycol and i assume antifreeeze of some sort. Question is - Can the in temp be 32 and the out temp drop to around 25 and still work? I assume it wont freeze but was just curiuos if it could work like that?
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Old 01-17-2011, 08:17 AM   #2
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Geothermal closed loop


It is not so much the outside air temp, but the ground temp that would allow it to do its job. The antifreeze is the Glycol. It basically works like a heat pump. Summer it pulls the cooler ground temp to cool the house, in Winter, it uses the warmer ground temp to help heat the house.

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Old 01-17-2011, 08:30 AM   #3
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Geothermal closed loop


i understand its the ground temp. I am just wondering if for some reason the loop may not be keeping up with the system and say the glycol coming in temp from the ground loop is 30 degrees and goes back to the ground loop at 20 degrees if the system will still work? I understand that the ground temp should be a constant 50 to 55, but wondering if the loop cools down can it all still work?
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Old 01-17-2011, 08:38 AM   #4
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Geothermal closed loop


Those temps? F or C,

At the temps you refer to no, how would you get any heat out of loop temp below or at freezing.

Sure it would work, if you were trying to cool something, but not for heat.
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Old 01-17-2011, 08:41 AM   #5
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Geothermal closed loop


The depth of the loop, the ground temp stays at a constant 50-60 degrees. Unless you live in Antarctica, Alaska, or the Artic Circle, the ground temp will never get that cold. The Glycol mix is at a ratio, just like your car's Glycol mix is always a 50/50 mix.

http://en.wikipedia.org/wiki/Geothermal_heat_pump
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Old 01-17-2011, 09:03 AM   #6
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Geothermal closed loop


Cool thanks, I just was wondering if the ground loop was to small and the ground around the pipes were cooling off as it runs more and more throughout the winter.

I live in the coldest part of the nation, just a few miles from the canadian border in northern MN.

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Old 01-17-2011, 09:32 AM   #7
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Geothermal closed loop


Quote:
I just was wondering if the ground loop was to small and the ground around the pipes were cooling off as it runs more and more throughout the winter.
Ayuh,... If the system is poorly designed, 'n the ground loop is so small, it can't exchange quick enough,...
Yer gonna freeze yer butt off, as the system won't be workin'...
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Old 01-17-2011, 10:11 AM   #8
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Geothermal closed loop


Thanks for the replies.
Its all heating fine, just started to notice a little frost on the lines.
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Old 01-17-2011, 10:34 AM   #9
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Geothermal closed loop


Take a picture and post back. Is the unit located in your garage or basement? Also, if the space around your income loops are not sealed from outside air entering, it may cause problems with frost on the outside of the lines, but it shouldn't under normal conditions. This year is seeing a Little Ice Age across the planet. http://en.wikipedia.org/wiki/Little_ice_age
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Old 01-17-2011, 10:44 AM   #10
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Geothermal closed loop


It is located in the garage and the garage is heated to 60 degrees.
There is actually a little frost on the lines entering and exiting each unit.
Just started showing up in the last few days. Lows arent to bad at night -10 or so and highs in the single digits.
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Old 01-17-2011, 08:54 PM   #11
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Geothermal closed loop


It depends on the Glycal concentration in the loop. If they used the recommended 15% mix you should have a -5 degree freeze protection. The other issue that you may run in to is slushing. this occurs when the solution in the loop is near the freeze point. once slushing occurs you are no longer extracting heat from the system and damage can occur. As of now you are still getting a temp drop between supply and return, so the system is working. Although you should really have you loop checked, you shouldn't have temps that low.
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Old 01-18-2011, 05:02 AM   #12
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Geothermal closed loop


Quote:
Originally Posted by LukeROttinger View Post
It depends on the Glycal concentration in the loop. If they used the recommended 15% mix you should have a -5 degree freeze protection. The other issue that you may run in to is slushing. this occurs when the solution in the loop is near the freeze point. once slushing occurs you are no longer extracting heat from the system and damage can occur. As of now you are still getting a temp drop between supply and return, so the system is working. Although you should really have you loop checked, you shouldn't have temps that low.
Luke's right.
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Old 01-18-2011, 07:28 AM   #13
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Geothermal closed loop


Thanks for the replies.
I dont actually know what temps are coming in and going out, i was just wondering if it could still work if that were to happen.

There are no temp gauges to check.
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Old 01-19-2011, 09:06 PM   #14
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Geothermal closed loop


Fisher, I have been thinking a little more about you question. I think that you need to have your loop checked, a pressure drop would account for your problem. This is vary common. Over time the pump can allow pressure to leak out or micro bubbles in the water can collect and form a pocket. I would love to know what you find out.
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Old 01-24-2011, 12:10 PM   #15
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Geothermal closed loop


well it is all back up and running.
Went to work on Thursday everything was fine. Came home and the underfloor was locked up and the forced air was blowing cold air. Very cold last few days lows were -37 and highs around -13. Problem ended up being the methenol levels were to low. In temp was 30 and the methonal levels was 28, so when it tried to take out 10 degrees, it was shutting down because it thought it was frozen but wasnt. Refilled the loop and hooked up the gas back up to get the house up to temp, was down to 52 in there. The methenol level is now at 15 so we should be good to go, no issues since and heating very well.
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