We have had weeks of daytime highs over 100 and morning lows in the mid 70's. My water temps on both systems are over 80. In 15 yrs. on the larger system and 10 on the 1 ton, they have never been so high. Anyone else heating up. BTW, both systems are working fine, just not cycling off until late at night.

At 77f two weeks ago, our EWT is very good, but we keep the thermostat on the second floor at 79 day/75 night, and first floor now at 77 day/75 night (previously 76 day, but trying to save a few bucks and help EWT by not running the system as much.) Our system may be about 1 ton over sized and the shared loop is over sized by 20%. We are in SW VA. Where are you and what is your loop configuration & size? Hot here, but not as hot as 100+ for weeks. We finally had a break with outdoor temps, cloud cover, and lots of rain recently.

Lots of articles about how hot 2010 has been. This is the first one I saw:
http://www.weather.com/outlook/weather-news/news/articles/warmest-temps-globe-jan-jul-2010_2010-08-13

Correction to my loop oversize percentage.  If a 4 ton system would have sufficed for us, that would have been 4 x 500'/ton = 2,000 feet of loop.  We have 5 x 600'/ton = 3,000 feet of loop, so that's 50% oversize.

In N. Ark. No rain for 3 wks. Already officially the hottest summer on record here. Ground temp. is 58 and I have 4, 400' Hor. loops on a 2 1/2 ton, home made system and 2, 400' loops for a 1 ton trane console that takes care of my garage. It's the one that runs almost non-stop as it's undersized for the 1000' space. The highest temps. before were around 78 at the end of cooling season but we may have another month before a break in this weather. I would love to be able to bank some of this heat I'm pumping in to the ground.

Posted By arkieoscar on 20 Aug 2010 10:55 PM 
I would love to be able to bank some of this heat I'm pumping in to the ground.

You probably will....short term. First time you heat the home you will have COPs higher than ever (unless there is a lengthy bumper season).
j

I want every BTU that I pumped in to the ground to be available in Jan. and Feb. Ha, ha.

GLWD! (good luck wid dat)

Closed loop EWT of merely 80 would be a dream come true down here in FL

Ya got no worries, mate!

Due to this heat wave in the mid atlantic as well, we are seeing the highest ewt's ever also.  Some are in the high 80's and still working fine, just extended run times.  One whose design was to tight to start with failed when the outdoor temps and the indoor setpoint both exceeded the design.
Eric

My ground loop delta measured at the manifold with probe thermometers is 7 F.

70 EWT
77 LWT

Stuart
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GeoMax 2, 4 ton, 2x300 foot boreholes, 2 loops per borehole, 14.4kw Aux, AirTap, Other Gadgets, etc. SE PA, USA