We have an older Water Furnace geothermal unit in our house(80's model according to repair guy). It runs and runs until the light on the thermostat marked "Emergency Heat" comes on. At this time it seems to stop cooling. I can turn the unit off for 30 seconds or so then back to cool. Sometimes it will return to normal operation and function properly. Other times it might run normal for a short period, turn the light on, and stop cooling again. We've been here about 9 years and have had this issue every summer to some degree. Its worse when the kids run in and out. I've lost trust in our repair man and was wondering if this is a problem I could resolve myself. The coils were supposedly cleaned in early spring and the pressure was checked in ground loop. Much thanks in advance to any suggestions.

There is 10 degree difference in the ground loop, 73 coming in, 83 going back to the ground. And 13 degree difference between return air and duct air, return 74, duct 61(out of a vent approximately 18 feet from unit). I don't know the loop length or configuration, the system was installed long before we bought the house. Judging by the space around the house I would assume it's wells and not trenched. I know the house(2400 sqft built in 78) is not as energy efficient as it could be. But its not too bad cause our power bills are reasonable, especially for having two kids that leave lights on and run in and out...alot. This has been an intermittent issue. It's like the unit runs till something "times out", it stops cooling but continues blowing. Turning it off then back on resets it somehow. I'm in southern Illinois, due east of St Louis about 60 miles.

I would bet a steak you have a condensate fault but a 14 degree T.D. on the evaporator coil could mean you are low on charge as well. Typically 18 - 22 degrees is acceptable depending on E.A.T. and Humidity. These fluctuate and are sometimes difficult to diagnose as they may not be completely stopped up, just draining slowly. 1 cup of bleach is your fix. If not, you are only out a cup of bleach.

Posted By tscat007 on 30 May 2017 11:29 PM
I would bet a steak you have a condensate fault but a 14 degree T.D. on the evaporator coil could mean you are low on charge as well. Typically 18 - 22 degrees is acceptable depending on E.A.T. and Humidity. These fluctuate and are sometimes difficult to diagnose as they may not be completely stopped up, just draining slowly. 1 cup of bleach is your fix. If not, you are only out a cup of bleach.

Depending on his airflow, 13F could be within specs if he has a bit too much airflow, especially with 10 degrees in the heat rejection, and the 73F of entering water loop temperature. The only way to check is to determine the capacity or the heat rejection, which commands the knowledge not only what the delta t is, but also the flow. In any case, the problem is likely solved, given that the last post is almost a year old....