A geothermal system is a heat pump that exchanges with a ground loop instead of outdoor air. That makes it reliable — and it means most problems come down to loop flow.
Know where to stop
Everything below is a check any homeowner can safely make. Anything involving opening a sealed refrigerant circuit, working inside an energized panel, or dismantling a gas train needs a licensed technician — not because we want the call, but because that is where people get hurt.
If you smell gas, leave the building and call the gas utility from outside.
Free things to try before you call
A good share of the calls we go out on turn out to be one of these. Try them first, and you may save yourself a service charge.
- 01
Check the thermostat is on HEAT, not emergency or auxiliary heat only
- 02
Replace the air filter and open all registers
- 03
Check breakers for the unit and for the loop circulator pumps
- 04
Look for a fault or lockout code on the unit’s control board and note it
- 05
Check loop pressure on the gauge if your system has one accessible
- 06
Listen for the circulator pumps running when the system calls for heat
- 07
Check whether auxiliary electric heat is carrying the load instead
What it probably is
These are the most likely causes. Open one to see what it looks like and what fixing it involves.
1Low loop flow or pressure
This is the most common geothermal fault. The cause can be air trapped in the loop, a failing circulator pump, or a slow leak dropping loop pressure. Without adequate flow there is nothing to extract heat from, so the unit locks out on a pressure or temperature fault.
2A failed circulator pump
The pumps move fluid through the ground loop. When one fails the unit has no heat source and will lock out rather than damage itself.
3A stuck reversing valve
As with any heat pump, the valve that switches between heating and cooling can stick, leaving the system in the wrong mode.
4Auxiliary heat carrying the load
The house stays warm while the electric backup does all the work and the bill climbs quietly. It is common when the geothermal side has failed but nothing has alarmed.
5Control or sensor faults
Geothermal units are well instrumented, so a failed sensor will often lock the unit out as a precaution even when the mechanical side is fine.
Common follow-ups
Do geothermal loops wear out?
The buried loop itself is extremely long-lived — it is inert pipe in the ground. The wear items are the circulator pumps, the heat pump unit and the controls, all of which are inside and accessible.
My bill jumped but the house is warm.
Classic sign that auxiliary electric heat has taken over from a geothermal side that is not working. Worth calling promptly, because it is expensive to leave running.
Can you service a geothermal system another company installed?
Yes. We service and repair geothermal from any installer, and we install new systems in Kingsport and the surrounding area.
Prefer to call?
(423) 357-1922- Office hours
- Monday to Friday, 8–5
- Outside those hours
- Emergency service is available — call the same number.
- Where we go
- Church Hill, Kingsport, Mount Carmel, Surgoinsville, Rogersville, Johnson City, Bristol, Greeneville, Morristown and across into Southwest Virginia. Full service area.
- Where we are
- 119 E Main St, Church Hill, TN 37642
Still not working after these checks?
That is what we are here for, and emergency service is available.
(423) 357-1922