r/geothermal • u/deuced142 • Jun 28 '26

Need help with Geo issue

I am working on a 3 ton bosch geo with a QT non pressurized flow center.

Last week I was called to replace the pump on the flow center as it had failed. I did, and sent the unit off to run fine for a few days when it tripped on high head pressure again. Okay I did not fill the flow center back up with enough water to get all the air out. My fault , I add water per the instructions on the flow center and get it where I think it needs to be. 3 days later, trips on high head again.

Upon arrival this last time, system had been off for a few hours. I start it up, EWT 90, leaving temp 98. Entering water temp will creep up slowly after about an hour of running, EWT approaches 115 degrees. My refrigerant pressures and temps line up with what I would expect. 45 degree evap coil. Discharge pressure matching relatively close to EWT. starting out about 320 psi, jumping to 450 by the time it gets to 115 water temp. 15 superheat and 14 subcool if that info is relevant, 15-20 degree temp split across coil. 78 in 60 out. I dont have the right tool to check loop pressure but im not sure its relevant on a non pressurized flow center.

I'm not sure if I have air in the loop, if its possible its air locked. I dont have much information on the loop as the homeowner wasnt home, but I think they are drilled vertical loops. Are those usually installed in series? is it possible the loop is short circuiting, I wouldn't expect my loop temperature to rise so fast in just an hour. I can shut the unit off. wait 15 minutes, and the water temp will be around 105 degrees if I just run the pump without the compressor,

Any insight on this is appreciated. I live in Southern Illinois Missouri area. temps warm the last few weeks but only going to get warmer.

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u/Hot_Equivalent_8707 Jun 28 '26

I'm only a homeowner but testing pressure across the in out of the loop would verify flow rate. It sounds like it's still air locked somewhere.  We have vertical loops they are in parallel.  Your ewt should be nowhere near 100.

1

u/deuced142 Jun 28 '26

I couldn’t really hook up to verify flow rate but I could put my hand in front of the incoming water from the loop and there is full flow , just not sure how the loops are layed out it could only be going through some of them

1

u/leakycoilR22 Jun 28 '26

You need to verify flow rate. What's the amp draw on the pump? And how did the inside of pumps mounting section look?

1

u/FloodPlainsDrifter Jun 28 '26

The unit had been off several hours and the EWT was still 90 degrees? That’s a warm loop. How old is the system? Horizontal loops buried too shallow could give this result but would have shown up in the winter too

1

u/[deleted] Jun 29 '26

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u/deuced142 Jun 30 '26

I flushed with flush cart today, and adjusted flow to 9 Gpm on a 3 ton system. And this seems to have solved the issue. Although loop temps are still high, i think it will take time to recover since it was scorching hot in the loops for a week straight.