Why a geothermal heat pump stops working well
Most geothermal heat pump problems come from the indoor equipment, not the buried loop: a clogged filter, a thermostat or control fault, low airflow, a refrigerant leak or a worn compressor. Loop problems are rarer but costlier, so it pays to rule out the simple causes before calling for a loop diagnosis.
What are the most common geothermal heat pump problems?
A ground-source system has two halves. Underground, a closed loop of buried pipe carries water or an antifreeze mix. Inside, the heat pump unit moves heat between that fluid and the house air or hot-water system. The indoor half has the moving parts, so it is where most faults show up.
- Airflow trouble. A dirty filter, blocked return or a dirty coil cuts airflow, and the system runs longer for less comfort.
- Control faults. A thermostat, sensor or relay problem can stop the unit from starting or leave it stuck in the wrong mode.
- Refrigerant leaks. A low charge reduces output and can damage the compressor if ignored.
- Compressor or reversing valve wear. These are the costly internal parts, and failure is more likely as the unit ages.
- Circulation pump or flow problems. Without good flow through the loop, the heat pump cannot exchange heat properly.
If you are not sure how the pieces fit, how ground-source heat pumps work gives the basic picture.
What can you check yourself before calling a technician?
Start with the cheap, safe items. Replace or clean the air filter, make sure supply and return vents are open and unblocked, and confirm the thermostat is set to the right mode with fresh batteries if it uses them. Check the breaker and the emergency or backup heat switch too. A tripped breaker is a common reason a unit seems dead.
Then note what the system is doing rather than guessing at the cause. Does it run constantly and never catch up? Does it short-cycle? Is the air from the vents cool in heating mode? Is there water around the unit? A technician can work much faster from those notes. Refrigerant and electrical panels need licensed work.
Can the ground loop itself fail?
It can, but it is uncommon. Modern loops are usually made of fused plastic pipe, and a well-installed loop is designed to outlast the heat pump unit. When trouble does appear it tends to be a leak at a fitting or header, trapped air, low fluid pressure, or a loop that was too small for the house so that circulating temperatures sink further each winter.
A technician can check loop pressure, flow and the temperature of fluid entering and leaving the heat pump. If the entering temperature is unusually low for your region and the season, the loop may be undersized or the ground may have been drawn down. Our guide on geothermal loop repair and replacement covers how leaks are located and what the fix involves.
The Drake Landing community in Okotoks shows why ground temperature matters. Its borehole storage field was deliberately charged with summer heat, and the system only worked because the ground temperature was managed. A single home's loop works the opposite way, drawing heat out, so its design has to leave enough margin for the coldest winters.
Is the problem the installation rather than the equipment?
Often, yes. Sizing, duct design and loop length are installation decisions, and mistakes there show up as symptoms that look like equipment faults. A system that never keeps up on the coldest days may have been sized without a proper heat-loss calculation. Cold rooms may come from ductwork designed for an older furnace.
If a new system has problems in its first season, go back to the installer with your notes, since workmanship and equipment warranties may apply. The guide to choosing a geothermal drilling contractor helps here.
When is it time to repair, and when to replace?
Match the repair to the part. Filters, sensors, thermostats and circulation pumps are modest repairs. A failed compressor in an older unit is a bigger decision, because the cost of the part and labour can approach a good share of a replacement. The loop is a different case: if it is still sound, replacing only the indoor unit can give a new system on the same ground investment.
Age, repair history, refrigerant type and parts availability all feed into the call, and the repair or replace decision guide lays out a general way to weigh them. Regular servicing catches many faults early, as described in geothermal heat pump maintenance. Costs depend on region, equipment and the technician's quote, so get the diagnosis in writing before agreeing to major work.
Quick answers
Why is my geothermal heat pump running but not heating?
Common causes are a clogged filter, low airflow, a control or reversing valve fault and a low refrigerant charge. Check the filter and thermostat first, then book a technician if the air stays cool.
How long do geothermal heat pumps last before faults appear?
The indoor unit typically lasts around two decades with service, while the buried loop is designed to last much longer. Faults before that point usually involve filters, controls or a refrigerant leak.
Is a geothermal repair covered by a warranty?
Many systems carry a parts warranty, and some installers add labour or loop coverage. Check the contract and the manufacturer terms, since coverage varies and often depends on documented servicing.
Can I fix a geothermal system myself?
You can change filters and check the thermostat and breaker. Refrigerant, electrical and loop work should go to a licensed technician.