Financing stories answer the question of who pays first. They do not tell you what the water in your ground loop is doing this winter or this summer. An ACHR News report on Enertech's geothermal leasing program describes a model that "eliminates upfront costs for homeowners." Whatever the paperwork says, the heat pump still moves heat with the same physics, and the unit still shows its condition through a few readings you can take yourself. This piece covers those readings.
What the Loop Is Telling You
A water-to-air geothermal heat pump exchanges heat between the house air and a closed loop of water or antifreeze solution. Three things tell you whether that exchange is working: the temperature of the water entering the unit, the temperature of the water leaving it, and how much water is moving through in the meantime. The difference between entering and leaving temperature, usually called delta T, is the number most people skip. It is also the one that changes first when something is wrong.
Set Up the Probes
Use a digital probe thermometer with a thin, fast-responding sensor, or a clamp-style surface probe if the water lines are accessible. Work on the supply and return lines at the unit, not at the buried loop. Put the probes on the copper or plastic pipe, then wrap them with foam pipe insulation and tape to keep room air from skewing the reading. A probe sitting on an uninsulated line in a cold utility room will read low on the water it is supposed to measure.
Before you take readings, confirm the power is off at the disconnect before you touch any wiring, and let the system run long enough to settle. Give it at least ten to fifteen minutes after the compressor starts. Early readings during startup show the pipes warming or cooling, not steady operation.
Read the Split
In heating mode, the loop gives up heat, so the water leaving the unit is cooler than the water entering it. In cooling mode, the unit rejects heat into the loop, so the water leaving is warmer. Write down both temperatures for each mode and subtract. Then compare the result with the performance data sheet from the manufacturer for your model, looking up the row that matches your measured entering water temperature and flow rate.
A split that falls well outside the data sheet range does not tell you the cause by itself. It tells you the unit is not doing what its rating says at the conditions you measured. That is the point where you narrow the list of suspects, not where you condemn the compressor.
Check Flow Before the Compressor
Flow problems produce many of the same symptoms as a weak compressor, so check flow first. Look for the pressure gauges on the water side, the flow switch if the unit has one, and the circulator pump that moves the water. A closed valve, a partly restricted filter, or air trapped in the loop can reduce flow enough to change the split and reduce capacity. If the circulator is supposed to run with the compressor and your multimeter shows no voltage at its terminals during a call for heat or cooling, the fault is in the control circuit or the wiring, not the ground.
Compare the compressor and fan amp draw with the nameplate rated load amps as a sanity check. A reading far above the nameplate figure, combined with a large or small delta T, points toward a problem that needs a technician with the right gauges and refrigerant training. Refrigerant work belongs with a licensed contractor, and so does any loop repair involving pressure, fittings, or pumping equipment.
Log It Before You Call
Keep one page with the date, outdoor air temperature, entering and leaving water temperatures, the mode, the amp reading, and the circulator voltage. Repeat the same readings on a mild day in spring and again during a cold snap. The pattern across seasons is more useful to a technician than a single panicked reading taken during a fault. If you call for service, hand over the log with the model and serial numbers from the nameplate.
A financing program can change who signs the check. It cannot change the water temperature at the unit, and it cannot make a low flow reading look normal. Measure the split, check flow, and write the numbers down before anyone decides what the loop needs.