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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Have a closed loop climate master geo system that is coming

Customer Question

Have a closed loop climate master geo system that is coming up with a E4 low water temp shutdown. I've had original installer look at it, they replaced some glycol and said they didn't know what else to do. I did some research and clipped the SW3 jumper but still shutdown. Watching the temps the LT1 stays around 12-14 deg for 3-4 minutes until the fan speeds up to full speed and the temp drops suddenly to 2-4 deg and it shuts down. Help
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.

Hello, the problem is most likely in low water flow through the ground water loop.

Tell me if the unit gets well water or if there is a closed circuit loop in plastic buried on the property.

If its well water clean the line strainers... If its a closed loop look for an air bleed at the high point of the ground loop connections at the climate master.

Tell me please about how old the system is, and is repair history.

We can go from there.

Customer: replied 1 year ago.
The system is about 15 years old. There are 3 total geo units, this one was replaced about 2 years ago and has had this problem since new on both the AC and heat cycles. The other 2 units work fine. Each unit has its own pumps (2) from a common closed loop source. There is about a 2 deg drop in the water temp. I'm concerned that the installer isn't familiar with geo units. This unit is a 2 ton, the others are a 4 ton and a 3 ton that seem to work fine with the Same pump setup.
Customer: replied 1 year ago.
There doesn't seem to be any air trapped. Fittings get warm when the pumps come on (60 deg versus 40)
Expert:  Phil replied 1 year ago.

Hello again,

Is that 2 degree temperature drop across the ground loop supply and return? I need the exact temperatures if that is the case. This points to non enough pipe in ground loop for the 2 ton unit.

For comparison get me the temperatures of the supply and return on the 3 and 4 ton units, running separately, then with both running at the same time... let them run for 15 minutes before you take those readings... 5 to 10 degree split bare minimum is most common... less than that points to plenty of water flow, but not enough heat exchange surface.

Can you elaborate extensively on these 60 vs 40 figures?

We can go from there.

Customer: replied 1 year ago.
The water piping temp was approximately 40 deg (ambient) until the pumps turned on and the temp in went to 59.2 in and 59.4 out (from thermostat). Right before cutoff LT1 -1.0, LT2 71.4, water in 60.1, water out 59.2. The unit had a modulating valve controlled by the unit, the actuator was removed and the valve is 100% open for troubleshooting. The other units are approximately 60 deg in and 58 deg out. I've tried to eliminate water flow as a problem.
Expert:  Phil replied 1 year ago.

Hello again, with only 0.9 degF differential on the 2 ton unit, there is very little heat transfer taking place. If the ground loop is too short on that system, then it will cool down a lot more than the ground loop on the 3 and 4 ton systems.

Run it for a while and do that comparison.

Further sets will require refrigeration service gauges to measure the compressor head and suction pressures.

Expert:  Phil replied 1 year ago.

If you can measure the supply and return air temperatures on the 2 ton unit that will help as well, be sure to do it before any electric resistance back comes on.

Repeat the test on the 3 and 4 ton units for a comparison.

We can go from there.