- Troubleshooting Common Problems in Ground Source Heat Pumps
A ground source heat pump (GSHP) system is one of the most reliable ways to heat and cool a commercial building. It runs quietly, costs less to operate than most traditional systems, and can last for decades with the right care. But even the best-built equipment has its moments.
Over time, performance can slip, temperatures fluctuate, pressure levels change, or you start hearing noises you shouldn’t. That’s when good ground-source heat pump troubleshooting makes all the difference. Understanding the common warning signs, what causes them, and how to respond helps prevent expensive downtime and keeps efficiency where it should be.
At National Pumps and Boilers, we’ve worked with countless GSHP systems in schools, offices, and industrial facilities. Some failures are obvious, others more subtle, but most can be fixed before they become serious. Below, you’ll find the most frequent GSHP issues, what they mean, and how to address them before they impact performance.
Why Ground Source Heat Pumps Are So Reliable
A GSHP works by transferring heat to and from the ground rather than producing it directly. The Earth beneath our feet stays at a consistent temperature, even when the air outside freezes or swelters. This stability makes GSHP systems ideal for large commercial environments that need predictable, low-cost climate control.
They offer clear advantages:
- Efficiency: They move heat instead of generating it, saving up to 50% on energy bills compared with conventional systems.
- Sustainability: Relying on renewable ground energy cuts carbon emissions significantly.
- Longevity: Underground loops last 50 years or more, while indoor units often exceed 20 years with proper maintenance.
Still, mechanical parts age, and heat exchangers or control systems can drift out of balance. That’s where knowing the signs of trouble becomes critical.
1. Low System Efficiency
When a GSHP starts using more energy than usual, the problem is often hiding in plain sight.
What You’ll Notice
- Higher energy bills despite similar usage
- Longer run cycles or slower temperature recovery
- Equipment that feels unusually warm or loud
Likely Causes
- Clogged air or water filters restricting flow
- Fouled heat exchangers that can’t transfer energy effectively
- Declining expansion vessel performance is causing unstable pressure
What to Do
Start simple. Clean or replace all filters; blocked filters force the pump to work harder and waste electricity. Then, inspect the heat exchanger for dust or scale. Even a thin film of debris can drop efficiency by 10–15%.
Check expansion vessels for pressure issues; a failed diaphragm can cause unstable operation and higher energy draw. National Pumps and Boilers supplies Expansion Vessels specifically built for large commercial installations where stability is key.
Field tip: If efficiency problems persist, review system logs from your Building Management System (BMS). A trend showing longer run times with no temperature gain almost always points to a flow or pressure fault.
2. Uneven Temperatures Across Zones
Temperature imbalance is one of the most common service calls we see in large buildings.
What You’ll Notice
- Hot and cold spots throughout the building
- Airflow differences between rooms
- Some zones are constantly calling for heat
Likely Causes
- Malfunctioning or partially closed pump valves
- Air trapped in the system
- Uneven flow in the ground loop
What to Do
Start with the pump valves. If one valve sticks or partially closes, it can cause an entire wing of a building to run too hot or too cold. Replace worn or corroded valves with reliable commercial-grade options from National Pumps and Boilers.
Next, bleed the air from the loops. Air pockets are notorious for interrupting water flow and reducing thermal transfer. Finally, rebalance the system to ensure equal flow across zones, a job best done with flow meters and a patient hand.
Analogy: A GSHP system is like a set of arteries. If one is blocked or restricted, circulation suffers everywhere. Keep the flow steady, and the whole system stays healthy.
3. Low or Fluctuating Pressure
Pressure is the heartbeat of a ground source heat pump. When it’s too high or too low, efficiency and reliability take a hit.
What You’ll Notice
- Sudden changes in heat output
- Frequent system cycling or cut-offs
- Alarms or fault codes from the controller
Likely Causes
- Leaks in pipework joints or seals
- Failing expansion vessel
- Air in the system displaces water volume
What to Do
Start by checking visible joints and valves for drips or residue. Even slow leaks reduce efficiency and can draw in air, causing noise or temperature swings. If no leaks appear, gauge the pressure at the expansion vessel. A reading outside the specification usually means the diaphragm is gone.
Replace the vessel if it can’t hold a stable pressure. National Pumps and Boilers offers Expansion Vessels engineered for commercial loop systems, built to withstand constant cycling.
Pro Tip: Don’t keep topping up the system with fresh water; it introduces oxygen and minerals that cause corrosion. Always fix the cause, not the symptom.
4. Unusual Noises
When a GSHP system starts talking to you, it’s trying to tell you something.
What You’ll Hear
- Rattling: Often loose mounts or fittings
- Hissing: Air trapped inside the circuit
- Knocking or clunking: Flow problems or cavitation in the pump
Likely Causes
- Trapped air in the loop
- Loose pipe brackets or fittings
- Pump bearings nearing the end of life
What to Do
Bleed the system first. Air pockets are the most common reason for hissing or knocking noises. Then, tighten fittings and check circulation pumps. If noise continues, bearings may be failing, a clear sign it’s time for ground-source heat pump repair.
Reliable replacements like Grundfos and Lowara models deliver smoother, quieter performance and lower vibration, extending the life of your installation.
5. Short Cycling or Unexpected Shutdowns
Frequent starts and stops reduce lifespan, increase energy costs, and frustrate building occupants.
What You’ll Notice
- The system switches on and off more often than usual
- Rooms never quite reach the target temperature
- Compressors running hot
Likely Causes
- Incorrect flow rates or undersized loops
- Sensor calibration drift
- Faulty thermostats or control settings
What to Do
Check flow rates first, too low, and the system overheats; too high, and energy is wasted. Recalibrate thermostats and ensure the controller is reading actual loop temperatures correctly.
If the issue persists, review the configuration within the Building Management System. A small adjustment in control logic can resolve cycling problems. Short cycling left unchecked often leads to premature compressor wear, requiring costly ground-source heat pump repair later.
Preventative Maintenance for Long-Term Efficiency
The best troubleshooting strategy is avoiding problems altogether. Proactive maintenance keeps small issues from becoming emergencies.
Routine Tasks
- Seasonal Testing: Run full heating and cooling cycles in spring and autumn to confirm readiness for peak seasons.
- Cleaning: Heat exchangers, strainers, and filters should be cleaned or replaced regularly to maintain smooth flow.
- Pressure Monitoring: Use digital tools to record readings weekly. Sudden changes flag early warning signs.
- Professional Servicing: Annual servicing allows engineers to recalibrate controls, verify pump performance, and inspect ground loops.
- Documentation: Keep a logbook or digital record of every inspection, pressure adjustment, and part replacement. Patterns in this data make diagnosing future issues far quicker.
Integrating Smart Technology
Many modern systems integrate with IoT-enabled devices that log live data on temperature, pressure, and power consumption. These digital tools turn ground-source heat pump troubleshooting from reactive guesswork into data-led maintenance.
For example, a BMS alarm showing a gradual increase in compressor current could indicate a fouled heat exchanger weeks before efficiency losses become noticeable.
Anecdote: When a Factory Ignored the Warnings
A plastics manufacturing site in Nottingham relied on a GSHP to keep its workshop climate stable. After a few years of reliable operation, staff began noticing higher bills and colder mornings. They assumed it was just age.
By the time our engineers arrived, pressure had dropped below safe limits, and one expansion vessel had ruptured internally. Several pump valves were seized half shut. The fix cost nearly £9,000, and all of it could have been prevented with one maintenance visit the previous year.
Since adopting a proper monitoring and service schedule, their system now runs 23% more efficiently. That’s the long-term value of preventive care and professional ground-source heat pump repair.
The Importance of Reliable Components
No troubleshooting guide is complete without mentioning the hardware itself. Using durable, properly specified parts ensures that repairs last and maintenance stays simple.
At National Pumps and Boilers, we supply:
- Central Heating Pumps for efficient circulation
- DHW Pumps for hot water reliability
- Pump Valves for stable flow regulation
- Expansion Vessels to maintain pressure
We also stock components from trusted names such as Vaillant, Lowara, Armstrong, Wilo, and DAB. Each part is tested for reliability under commercial load conditions, exactly what large buildings demand.
Partnering with National Pumps and Boilers
Commercial buildings depend on systems that simply work, day in, day out. That’s why National Pumps and Boilers combines quality components with expert technical guidance.
Our engineers provide:
- System design advice for optimal performance
- Component matching to ensure compatibility and reliability
- On-site technical support for complex installations or ground-source heat pump repair
When you partner with us, you get more than products; you gain access to decades of trade experience and practical problem-solving.
Final Thoughts
A ground source heat pump is one of the smartest investments a commercial property can make. But even the best system will only perform as well as it’s maintained. The secret lies in consistency, monitoring, cleaning, and tuning before small faults turn into big repairs.
By applying solid ground-source heat pump troubleshooting principles, keeping maintenance records, and using proven components, you can expect years of efficient, reliable service.
Take care of the system, and it will quietly take care of your building.