Refrigerant Leakage in Heat Pumps

Refrigerant leakage is the unintended escape of refrigerant from a heat pump’s closed refrigerant circuit. The leak lowers the refrigerant charge. This can reduce heating capacity, cooling capacity, efficiency and operating reliability.

Leakage control combines leak-resistant system design, correct installation, operating-data monitoring, qualified leak detection, root-cause repair and documented recommissioning. It matters because a refrigerant leak can increase electricity use, reduce comfort, raise service costs, create refrigerant-specific safety risks and release greenhouse gases. Research by the US National Institute of Standards and Technology identifies refrigerant undercharge as an installation fault that can significantly reduce heat pump performance and increase annual energy use. EU law also requires operators to prevent emissions and repair detected leaks without undue delay.

Refrigerant leakage at a glance

Important distinction: Refrigerant leakage is not needed and has no useful purpose. Refrigerant leakage prevention and management are needed.

Definition of refrigerant leakage

A refrigerant is the working fluid that transports heat inside a heat pump. It evaporates, compresses, condenses and expands in a continuous closed cycle. A correctly sealed heat pump circulates the refrigerant rather than consuming it.

Refrigerant leakage occurs when some of this working fluid escapes through an unintended opening. The opening may be microscopic, intermittent or clearly visible as physical damage. Even a small leak can gradually reduce the refrigerant charge over months or years.

Refrigerant leak, refrigerant loss and low charge

These terms describe related but different conditions:

• Refrigerant leak: The physical defect that allows refrigerant to escape.
• Refrigerant loss: The amount of refrigerant that has left the system.
• Low refrigerant charge: The operating condition created when too little refrigerant remains.
• Incorrect initial charge: Too little or too much refrigerant added during commissioning.
• Service loss: Refrigerant lost during incorrect maintenance or repair work.

A heat pump with low refrigerant charge does not automatically prove that an active leak exists. The system may have been charged incorrectly during installation. A qualified technician must identify the actual cause before adding refrigerant.

What is not necessarily a refrigerant leak?

Several normal or unrelated conditions can look like leakage:

• Water below an outdoor air-source heat pump may be condensate or defrost water.
• Moisture on a cold pipe may be surface condensation.
• A water or glycol leak belongs to the hydraulic or source circuit, not the refrigerant circuit.
• Steam-like vapour near an outdoor unit can occur during cold-weather defrost.
• Frost on the evaporator can be normal under some operating conditions.

These observations still deserve attention when they appear unusual. However, they do not confirm refrigerant leakage on their own.

Core purpose of refrigerant leakage control

The purpose of refrigerant leakage control is to keep the working fluid inside the heat pump for the complete equipment lifecycle. Effective containment allows the heat pump to operate with its designed refrigerant mass, pressure conditions and heat-transfer capacity.

Leakage control also connects technical operation with environmental protection. The system must remain tight during manufacturing, transport, installation, operation, maintenance and decommissioning. Refrigerant must be recovered rather than released when equipment is repaired or taken out of service. EU operator duties include emission prevention, qualified servicing, recordkeeping and recovery of F-gases from decommissioned equipment.

The main purposes are:

1. Maintain heat transfer.
   The correct charge supports the designed heating and cooling capacity.
2. Protect energy efficiency.
   A correctly charged system avoids unnecessary compressor operation.
3. Prevent environmental emissions.
   Refrigerants with a high global warming potential can have a significant climate effect when released.
4. Manage safety risks.
   Refrigerants have different flammability, toxicity and pressure characteristics.
5. Protect equipment.
   Stable operating conditions reduce avoidable stress on the compressor and other components.
6. Meet legal duties.
   Covered systems may require periodic leak checks, records and certified personnel.

Why refrigerant leakage control is needed

Climate protection

Many existing heat pumps use fluorinated refrigerants. These substances can have a much greater warming effect per kilogram than carbon dioxide. The environmental significance of a leak therefore depends on both the amount released and the refrigerant’s global warming potential.

The climate impact is calculated as carbon dioxide equivalent:

CO₂ equivalent in tonnes = refrigerant released in kilograms × GWP₁₀₀ ÷ 1,000

For example:

The values show why refrigerant type matters. A kilogram of R410A has a much greater direct climate impact than a kilogram of R290. However, low-GWP refrigerants still require tight systems because leakage can affect performance and may create safety risks.

Energy efficiency

A heat pump needs the correct refrigerant charge to transfer heat efficiently. When refrigerant escapes, the mass flow through the evaporator, compressor and condenser changes. The system may need to operate longer to deliver the same room temperature or hot-water output.

Possible results include:

• Lower heating capacity
• Lower cooling capacity
• Longer compressor operating periods
• More frequent use of auxiliary heating
• Reduced seasonal efficiency
• Higher electricity consumption
• Unstable pressure and temperature conditions
• Repeated fault messages

The exact effect depends on the heat pump design, operating point and severity of the leak. NIST research found that refrigerant undercharge is among the faults most likely to cause significant heat pump performance degradation and increased annual energy use.

Comfort and service continuity

A gradual leak may first appear as a comfort problem. Rooms may warm more slowly. Domestic hot water may take longer to recover. The system may struggle during periods of high demand.

In a commercial building, the same fault can affect tenants, guests, employees or production processes. A small technical defect can therefore become a business continuity problem. Early diagnosis reduces the risk of an unexpected shutdown during cold or hot weather.

Safety

Refrigerants have different safety classifications. ISO 817 classifies refrigerants according to toxicity and flammability and establishes refrigerant concentration limits for safe use. The letter generally indicates the toxicity group, while the number and “L” designation indicate the flammability group.

Examples include:

• A1: Lower toxicity and no flame propagation under the classification test.
• A2L: Lower toxicity and lower flammability with a low burning velocity.
• A3: Lower toxicity and higher flammability.
• B2L: Higher toxicity and lower flammability.

R32 and R454C are classified as A2L. R290 propane is A3. R744 carbon dioxide is A1. R717 ammonia is B2L. The refrigerant classification influences charge limits, room requirements, equipment construction, installation positions and service procedures.

A low-GWP value does not remove the need for safety engineering. R290 has very low direct climate impact but requires controls appropriate for a flammable refrigerant. R744 has low GWP but operates in systems designed for high pressure. R717 has very low GWP but requires controls for toxicity.

Business and financial risk

An unresolved leak creates costs beyond the price of replacement refrigerant. It may cause repeated service visits, emergency call-outs, loss of heating or cooling, tenant complaints and avoidable electricity use.

Common business effects include:

Leakage management changes maintenance from a reactive activity into a controlled asset-management process.

Legal compliance

Regulation (EU) 2024/573 establishes rules for the containment, use, recovery, recycling, reclamation and destruction of fluorinated greenhouse gases. It also regulates certification, training, leak checks and records. The regulation entered into force on 11 March 2024.

The regulation applies directly in EU Member States, including:

• Austria
• Germany
• Italy, including South Tyrol
• Spain
• Poland
• Finland

National authorities remain responsible for implementation, certification systems, inspections and penalties. Switzerland is not covered by the EU regulation and applies its own refrigerant rules under the Chemical Risk Reduction Ordinance.

How a refrigerant leak affects the heat pump cycle

A heat pump transfers energy through four main refrigeration processes:

1. Evaporation
   The refrigerant absorbs heat from outdoor air, ground, groundwater or another source.
2. Compression
   The compressor increases the refrigerant pressure and temperature.
3. Condensation
   The refrigerant releases useful heat to the building’s heating or hot-water system.
4. Expansion
   The expansion device reduces the refrigerant pressure before the cycle starts again.

A leak reduces the available mass of refrigerant. The evaporator may no longer receive the intended refrigerant flow. The compressor and heat exchangers then operate outside their designed balance.

Depending on the system, low charge can cause:

• Low suction pressure
• High superheat
• Reduced evaporator use
• Lower heat-transfer capacity
• Longer compressor runtime
• Increased discharge temperature
• Irregular oil return
• Low-pressure safety shutdowns
• Unstable expansion-valve control

These indicators are technical evidence, not automatic proof of a leak. Airflow, source temperature, water flow, sensor faults, blocked heat exchangers and incorrect commissioning can produce similar symptoms. A qualified diagnosis must consider the complete system.

Key features of effective refrigerant leakage management

An effective leakage management system contains seven connected features:

1. Leak-resistant refrigerant circuit design
2. Correct installation and commissioning
3. Operating-data monitoring
4. Direct leak detection
5. Automatic detection and alarm handling
6. Root-cause repair and verified recommissioning
7. Documentation and end-of-life recovery

No single feature provides complete protection. Monitoring can identify abnormal behaviour but may not locate a leak. A detector can identify refrigerant but cannot correct the defective joint. Repair restores the circuit, while documentation proves that the work was completed correctly.

Detailed explanation of leakage management features

Leak-resistant refrigerant circuit design

• Definition: Leak-resistant design reduces the number of joints, minimises refrigerant charge and protects components against vibration, pressure and mechanical damage.
• Purpose: It prevents leakage before the heat pump enters service.
• Benefits: The system requires fewer field connections and offers more stable long-term operation.
• Example: A self-contained heat pump may use a factory-assembled refrigerant circuit and transfer heat to the building through water pipes.

Good design may include:

• Factory-tested refrigerant circuits
• Brazed or welded permanent joints where suitable
• Protected service valves
• Vibration isolation
• Correct pipe support
• Corrosion-resistant materials
• Low refrigerant charge
• Accessible inspection points
• Component placement that limits accidental damage

A small charge reduces the quantity that could escape. It does not make leakage prevention unnecessary.

Correct installation and commissioning

• Definition: Installation quality covers refrigerant connections, pipe routing, pressure testing, evacuation, charging and functional testing.
• Purpose: It prevents defects created during installation.
• Benefits: Correct commissioning provides a reliable operating baseline and reduces early-life failures.
• Example: A split heat pump receives a documented tightness test and is charged according to the manufacturer’s specified pipe length and charge procedure.

Important installation controls include:

• Correctly prepared connections
• Approved joining methods
• Supported refrigerant pipes
• Protection against vibration and abrasion
• Pressure testing under the manufacturer’s procedure
• Correct evacuation
• Refrigerant charging by specified mass
• Recording of the installed refrigerant type and quantity
• Functional testing under stable conditions
• Handover of commissioning records

EU rules require certified or appropriately qualified persons for covered installation, servicing, repair, leak checking, decommissioning and refrigerant recovery activities. Certification and training also cover the safe handling of alternative refrigerants.

Operating-data monitoring

• Definition: Operating-data monitoring compares current heat pump behaviour with expected temperatures, pressures, runtimes, energy use and heating output.
• Purpose: It identifies performance changes before complete system failure.
• Benefits: Earlier awareness supports planned service instead of emergency repair.
• Example: A facility manager notices that compressor runtime and electricity use are increasing while delivered heat remains unchanged.

Useful data can include:

• Source inlet and outlet temperatures
• Heating flow and return temperatures
• Compressor runtime
• Compressor starts
• Electrical consumption
• Delivered heat
• Seasonal performance
• Pressure or temperature alarms
• Expansion-valve behaviour
• Auxiliary heater use
• Defrost frequency
• Historical fault codes

Monitoring identifies deviations. It normally cannot confirm the physical location of a refrigerant leak. Automatic fault detection can identify patterns consistent with incorrect refrigerant charge, but direct testing is still needed.

Direct leak detection

• Definition: Direct detection tests for refrigerant at a suspected leak location.
• Purpose: It confirms that refrigerant is escaping and helps locate the defect.
• Benefits: The technician can repair the actual leak instead of treating only the low-charge symptom.
• Example: A refrigerant-sensitive electronic detector identifies leakage around a service valve connection.

Common professional methods include:

• Electronic refrigerant detectors
• Refrigerant-specific sensors
• Leak-detection spray or bubble solution
• Visual inspection for oil traces or physical damage
• Approved tracer-gas procedures
• Pressure testing under the manufacturer’s method
• Section-by-section testing of larger systems

The selected method must suit the refrigerant and system. A detector intended for one refrigerant family may not provide suitable sensitivity for another. Testing must also account for ventilation, background contamination and equipment access.

Fixed leakage detection systems

• Definition: A fixed leakage detection system continuously monitors an equipment area or refrigerant circuit and produces an alarm when its detection threshold is reached.
• Purpose: It provides rapid warning without waiting for a scheduled inspection.
• Benefits: Early notification can limit refrigerant loss, improve safety response and reduce downtime.
• Example: A large plant room sends an alarm to the building management system when a refrigerant sensor detects an abnormal concentration.

A fixed system may include:

• Refrigerant sensors
• Pressure or density monitoring
• Local visual and acoustic alarms
• Automatic heat pump shutdown
• Mechanical ventilation control
• Building management system integration
• Remote alarm transmission
• Sensor fault supervision
• Calibration and function checks

Large F-gas systems can be legally required to use leakage detection. Smaller systems may also use sensors where the refrigerant, room volume, charge or building risk assessment justifies them. The detection system itself needs inspection and maintenance.

Root-cause repair

• Definition: Root-cause repair removes or replaces the defective component that allowed refrigerant to escape.
• Purpose: It restores circuit integrity rather than temporarily correcting the refrigerant quantity.
• Benefits: It prevents repeated loss, repeated service cost and continued emissions.
• Example: A damaged valve core is replaced, the circuit is tested, evacuated and recharged to the documented specification.

Adding refrigerant without locating and correcting the leak is not a complete repair. It may temporarily improve operation, but the refrigerant can escape again. EU rules require leaks to be repaired without undue delay.

A complete repair normally includes:

1. Confirm the fault.
2. Recover refrigerant where required.
3. Isolate the affected circuit.
4. Repair or replace the defective part.
5. Test the repaired circuit for tightness.
6. Evacuate the circuit according to the service procedure.
7. Recharge with the correct refrigerant and mass.
8. Confirm operating performance.
9. Check the repair after the required operating period.
10. Document the work and refrigerant movement.

Verified recommissioning

• Definition: Recommissioning confirms that the repaired heat pump operates within its intended conditions.
• Purpose: It verifies both circuit tightness and restored heat pump performance.
• Benefits: The operator receives evidence that the fault has been corrected.
• Example: The technician compares post-repair temperatures, pressures, electrical input and heating output with the manufacturer’s operating data.

Verification may include:

• Leak-testing results
• Refrigerant mass added or recovered
• Stable pressure and temperature readings
• Superheat and subcooling where applicable
• Heating or cooling output
• Electrical input
• Alarm history
• Expansion-valve control
• Compressor operating conditions
• Confirmation of sensor operation

For equipment subject to EU Article 5 leak checks, German Federal Environment Agency guidance explains that the post-repair effectiveness check must take place no earlier than after 24 operating hours and no later than one month after repair. The repair and check must be recorded.

Documentation and refrigerant records

• Definition: Documentation records the equipment, refrigerant, charge, inspections, losses, repairs and recovery activities.
• Purpose: It creates technical history and evidence of compliance.
• Benefits: Future technicians can diagnose the system faster and operators can demonstrate responsible management.
• Example: A service record lists the leak location, repair method, refrigerant recovered, refrigerant added and verification result.

A strong equipment record contains:

• Manufacturer and model
• Serial number
• Installation location
• Refrigerant designation
• Original charge
• CO₂-equivalent value where relevant
• Hermetically sealed status
• Installation and commissioning date
• Leak-check dates and results
• Detected leak locations
• Repair dates and actions
• Refrigerant recovered or added
• Technician and company identification
• Follow-up check results
• Decommissioning and recovery information

EU operators must retain relevant F-gas installation and servicing records for at least five years where the regulation applies. They must also ensure recovery of F-gases at end of life.

How to respond to a suspected refrigerant leak

A suspected leak requires a controlled response. Owners and facility managers should collect information but should not open the refrigerant circuit. Work involving refrigerant recovery, charging, repair or leak testing must be assigned to personnel with the required qualifications.

Step 1: Record the symptoms

Document what changed and when it changed.

Record:

• Fault code
• Date and time
• Outdoor temperature
• Heating flow temperature
• Room or hot-water performance
• Unusual runtime
• Electricity-use changes
• Visible frost or oil traces
• Recent maintenance or construction work

Historical information helps distinguish a progressive leak from a temporary operating condition.

Step 2: Check for an immediate safety concern

Identify the refrigerant from the equipment label or technical documentation. Follow the manufacturer’s safety and fault instructions. Keep ignition sources away from any area where a flammable refrigerant release is suspected.

Do not:

• Open the heat pump casing without authorisation
• Loosen refrigerant fittings
• Search with a flame
• Bypass alarms or safety controls
• Add an unapproved refrigerant
• Operate damaged equipment contrary to the manufacturer’s instructions

Step 3: Review operating data

Compare present operation with normal historical behaviour. A sudden reduction in output is different from a gradual seasonal change. Review whether the source temperature, heating-water flow or building demand has also changed.

Step 4: Contact qualified service

Provide the service company with:

• Heat pump model and serial number
• Refrigerant designation
• Fault code
• Symptom history
• Recent service records
• Photos of visible damage where safe
• Current operating data

This information supports faster preparation and diagnosis.

Step 5: Confirm the operating fault

The technician checks whether the symptoms are caused by refrigerant charge, water flow, source conditions, sensors, controls, heat exchangers or another fault. The diagnosis should consider the whole heat pump.

Step 6: Locate the leak

The technician selects a direct detection method suited to the refrigerant and equipment. Large or complex systems may need section-by-section isolation.

Step 7: Repair the defect

The remaining refrigerant is handled according to the repair procedure. The defective valve, joint, pipe, seal or component is repaired or replaced.

Step 8: Test and recharge

The circuit is tested for tightness. It is then evacuated and charged with the correct refrigerant and quantity. Refrigerant blends require the prescribed charging procedure.

Step 9: Verify performance

The heat pump is tested under stable operation. The technician confirms that heat transfer, electrical input, temperatures, pressures and controls are reasonable for the operating conditions.

Step 10: Document and follow up

The service record must state what was found and what was done. Any legally required follow-up check must be scheduled and completed.

Signs of refrigerant leakage

A refrigerant leak may develop slowly. Early symptoms are often indirect and can resemble other heat pump problems.

Possible signs include:

• Reduced room-heating capacity
• Slow domestic hot-water recovery
• Longer compressor runtime
• Increasing electricity consumption
• More frequent auxiliary heater operation
• Low-pressure alarms
• Repeated system lockouts
• Abnormal refrigerant pressure or temperature readings
• Unusual frost distribution on a heat exchanger
• Oil residue around a refrigerant joint
• Visible mechanical damage to refrigerant piping
• Repeated need for refrigerant top-ups

No single sign proves that refrigerant is leaking. A blocked filter, poor water flow, low source temperature, defective sensor or incorrect control setting can produce similar results.

Oil traces as an indicator

Refrigeration oil circulates in small quantities with the refrigerant. An oily area around a valve, joint or pipe can therefore indicate a leak. However, residue from previous service work can also remain on a component.

The technician must clean, test and reassess the location. Visual evidence should support diagnosis rather than replace direct testing.

Frost and ice

Ice on a heat exchanger does not automatically mean refrigerant loss. Air-source heat pumps regularly form frost in cold and humid weather and remove it through a defrost cycle. Uneven, persistent or unexpected icing can indicate a fault, but the cause may also be restricted airflow, sensor error or drainage problems.

Rising electricity consumption

Higher electricity consumption may result from colder weather, different occupancy, higher hot-water demand or changed temperature settings. It becomes more relevant when energy use rises while useful heat and comfort decline. Historical energy and heat-output data improve fault detection.

Common refrigerant leak locations and causes

Refrigerant pipe connections

Connections are potential leakage points because they experience pressure, temperature changes and vibration. Field-made connections require especially careful installation.

Purpose of control: Ensure the joint remains tight under all operating conditions.

Benefit: Lower risk of early and recurring leakage.

Example: A split-system refrigerant connection is supported so compressor vibration does not load the joint.

Service valves and valve cores

Service valves allow technicians to access the circuit. Damaged seals, loose caps or worn valve cores can allow refrigerant to escape.

Purpose of control: Protect the service access point after commissioning.

Benefit: Prevent small, persistent losses.

Example: A leaking valve core is replaced and the protective cap is fitted to the specified condition.

Vibration and material fatigue

Compressors, fans and pumps create vibration. Poorly supported pipes can move and develop fatigue cracks.

Purpose of control: Separate vibration from vulnerable pipe sections and joints.

Benefit: Longer circuit life.

Example: Pipe supports and flexible sections prevent repeated movement at a brazed connection.

Thermal cycling

Refrigerant pipes and components expand and contract as temperatures change. Repeated cycling can stress weak joints or materials.

Purpose of control: Design and install the circuit for the expected temperature range.

Benefit: Reduced long-term fatigue.

Example: Pipe routing allows controlled expansion without rubbing against the casing.

Corrosion

Moisture, salt, chemicals or incompatible materials can damage pipes and heat exchangers. Coastal locations and industrial atmospheres may require additional protection.

Purpose of control: Prevent material degradation.

Benefit: Lower probability of hidden pinhole leaks.

Example: A heat exchanger receives corrosion protection suited to the local environment.

Mechanical damage

Construction work, garden equipment, transport or incorrect servicing can damage a refrigerant pipe.

Purpose of control: Protect the refrigerant circuit from external impact.

Benefit: Reduced risk of sudden loss.

Example: Refrigerant lines are routed away from drilling zones and protected against impact.

Heat-exchanger defects

A refrigerant-to-air or refrigerant-to-water heat exchanger may develop a leak because of corrosion, fatigue, freezing damage or manufacturing defects.

Purpose of control: Identify whether the defect is local and repairable or requires component replacement.

Benefit: A durable repair decision.

Example: A leaking plate heat exchanger is replaced and the connected water circuit is checked for contamination.

Incorrect service practices

Improper connection of service tools, venting, incorrect refrigerant recovery or incompatible refrigerants can cause loss and system damage.

Purpose of control: Ensure work follows approved procedures.

Benefit: Lower emissions and reliable recommissioning.

Example: Refrigerant is recovered into suitable equipment rather than released during component replacement.

Types of refrigerant leakage

Slow or microscopic leakage

A slow leak releases a small quantity over an extended period. It may not cause an immediate alarm. Performance can decline gradually.

Purpose of classification: Support trend-based monitoring and detailed testing.

Benefit: The leak may be repaired before the system stops.

Example: A service valve loses a small amount over several heating seasons.

Intermittent leakage

An intermittent leak appears only under certain pressures, temperatures or vibration conditions. The circuit may appear tight while idle.

Purpose of classification: Ensure testing reproduces relevant operating conditions.

Benefit: Reduces the risk of an incorrect “no leak found” result.

Example: A joint leaks only when the discharge line becomes hot.

Operational leakage

Operational leakage occurs while the compressor or a specific circuit is active. Pressure differences and component movement can open the leak path.

Purpose of classification: Connect leakage with operating state.

Benefit: Helps the technician choose the correct test timing.

Example: A vibration-related pipe crack releases refrigerant only during high compressor speed.

Standing leakage

Standing leakage continues while the heat pump is switched off. It can often be detected through static testing.

Purpose of classification: Separate constant defects from operating-dependent defects.

Benefit: Supports faster isolation.

Example: A damaged valve seal leaks at system standstill.

Sudden or major leakage

A sudden leak releases a significant amount in a short time. It may result from pipe rupture, impact or major component failure.

Purpose of classification: Trigger an immediate safety and service response.

Benefit: Limits exposure and secondary damage.

Example: Construction work punctures an external refrigerant line.

Recurrent leakage

A recurrent leak returns after previous service. This can indicate incomplete repair, vibration, contamination or another unresolved root cause.

Purpose of classification: Move the investigation beyond the last repaired point.

Benefit: Prevents repeated top-ups and repeated downtime.

Example: A replacement joint fails again because pipe movement was never corrected.

Heat pump models and leakage implications

Self-contained or monoblock heat pumps

A self-contained heat pump keeps the refrigeration circuit within one factory-assembled unit. The building normally connects through a water circuit rather than field-installed refrigerant lines.

Purpose: Reduce refrigerant work at the installation site.

Benefit: Fewer site-made refrigerant joints can reduce installation-related leakage opportunities.

Example: An outdoor monoblock transfers heat to the building through insulated flow and return water pipes.

A monoblock is not leak-proof by definition. It still contains a compressor, valves, heat exchangers and factory joints. Product location, water-side frost protection and refrigerant safety requirements also remain relevant.

Split heat pumps

A split system has separate indoor and outdoor units connected by refrigerant pipes. Refrigerant connections are completed on site.

Purpose: Allow flexible indoor and outdoor component placement.

Benefit: The building water circuit can remain indoors in many configurations.

Example: An outdoor evaporator-compressor unit connects to an indoor hydraulic module through refrigerant lines.

Installation quality has a strong influence on circuit integrity. Correct pipe preparation, joining, testing and support are essential. Split design does not automatically mean poor reliability, but it creates more field-installed refrigerant interfaces.

Indoor ground-source or water-source heat pumps

Many ground-source and groundwater heat pumps contain the refrigerant circuit within an indoor unit. The heat source connects through brine or water pipes.

Purpose: Transfer ground or groundwater energy to the heating circuit.

Benefit: The refrigerant circuit can be compact and factory assembled.

Example: An indoor ground-source heat pump exchanges heat between a brine loop and the building water circuit.

Indoor placement requires product-specific consideration of refrigerant charge, room size, ventilation, ignition sources and drainage.

Large and multi-circuit heat pumps

Large heat pumps may use several compressors or independent refrigeration circuits. They can serve apartment buildings, hotels, commercial buildings, district heating or industry.

Purpose: Provide higher capacity and partial-load flexibility.

Benefit: Multiple circuits may preserve partial operation if one circuit is unavailable.

Example: A large heat pump uses separate modules so maintenance can occur without stopping all heat production.

Large systems require structured records, alarm management and clear circuit identification. Their refrigerant charge can also place them within more demanding leak-check or detection requirements.

Refrigerant types and leakage implications

Refrigerant selection must consider climate impact, thermodynamic performance, flammability, toxicity, pressure, system design and the installation environment. There is no single refrigerant that is optimal for every heat pump and every building. ISO safety classifications and product-specific engineering must be considered together.

EU Commission information identifies R290, R744, R454C and R32 among alternatives for domestic self-contained heat pumps. It identifies R290, R744 and R717 among options for industrial heat pumps. Suitability depends on the complete application rather than GWP alone.

Natural refrigerant does not mean risk-free

“Natural refrigerant” describes substances such as propane, carbon dioxide and ammonia that occur naturally or are based on naturally occurring compounds. It does not mean the substance can be handled without training or safety controls.

Each refrigerant has different characteristics:

• R290 requires flammability management.
• R744 requires high-pressure engineering.
• R717 requires toxicity management.
• Water and air refrigerant systems have their own application limits.

The correct objective is not simply to select the lowest GWP. The objective is to select a safe, efficient, compliant and serviceable system with low lifecycle environmental impact.

Use cases for refrigerant leakage management

Single-family homes

• Definition: A residential heat pump supplies space heating, cooling and possibly domestic hot water.
• Purpose: Leakage management protects comfort and household energy use.
• Benefit: Early attention reduces the risk of winter heating loss and emergency repair.
• Example: The homeowner notices longer runtimes and reports the operating history before the next failure.

Homeowners can be treated as operators under EU rules when they have actual control over covered equipment. German Federal Environment Agency guidance gives examples in which private heat-pump owners become responsible for periodic leak checks because the refrigerant charge reaches the applicable threshold.

Multi-family buildings

• Definition: One heat pump or a cascade supplies several apartments.
• Purpose: Leakage management protects shared heating and hot-water service.
• Benefit: Structured alarms and records reduce disruption for several occupants.
• Example: A property manager links fault alarms to the maintenance contractor and keeps a central equipment log.

A small performance decline can create many complaints. Clear responsibility between owner, property manager, operator and service provider is therefore important.

Hotels, offices and public buildings

• Definition: Commercial heat pumps serve larger and more variable loads.
• Purpose: Leakage management maintains indoor comfort and service continuity.
• Benefit: Planned repair reduces room closures, complaints and operational disruption.
• Example: A building management system identifies declining heat output per unit of electricity and creates a maintenance alert.

Performance baselines are especially valuable in buildings with occupancy changes. Energy data should be normalised for weather and demand before assuming a refrigerant fault.

Industrial and process heat

• Definition: Industrial heat pumps provide process heating, cooling or heat recovery.
• Purpose: Leakage control protects production availability and process temperatures.
• Benefit: Multi-circuit monitoring and planned maintenance reduce production downtime.
• Example: Each refrigerant circuit has separate sensors, alarm thresholds and service records.

Industrial installations may use larger charges or refrigerants such as R717 or R744. Their safety, detection and emergency plans are more site-specific.

Legacy heat pumps using higher-GWP refrigerants

• Definition: Existing systems may contain refrigerants such as R410A.
• Purpose: Leakage management limits emissions and supports an informed repair-or-replacement decision.
• Benefit: The owner avoids repeated refrigerant loss and can plan future equipment replacement.
• Example: A recurring leak prompts a lifecycle comparison between another major repair and a new low-GWP heat pump.

A different refrigerant cannot normally be added as a simple substitute. Refrigerant properties affect compressor design, pressure, lubrication, heat exchangers, controls and safety certification. Retrofit suitability must be confirmed by the equipment manufacturer or a qualified engineering assessment.

New low-GWP heat pump projects

• Definition: New projects use refrigerants and system designs selected for current and future environmental requirements.
• Purpose: The project reduces direct refrigerant climate impact while maintaining efficiency and safety.
• Benefit: Better regulatory durability and lower exposure to future F-gas restrictions.
• Example: A self-contained R290 heat pump is selected after verifying siting, safety distances, charge and service access.

Benefits of effective refrigerant leakage management

Environmental benefits

• Lower direct greenhouse-gas emissions
• Better use of low-GWP refrigerants
• Controlled recovery at end of life
• Less replacement refrigerant consumption
• Improved lifecycle environmental performance

Energy benefits

• Stable heating and cooling output
• Lower risk of inefficient long runtimes
• Reduced auxiliary heater use
• Better seasonal performance
• More reliable energy forecasting

Operational benefits

• Earlier fault recognition
• Fewer emergency call-outs
• Reduced unplanned downtime
• Faster diagnosis through records
• More predictable maintenance

Financial benefits

• Lower risk of repeated refrigerant top-ups
• Reduced avoidable electricity cost
• Better protection of compressor and components
• Improved maintenance budgeting
• Stronger repair-versus-replacement decisions

Compliance benefits

• Evidence of required leak checks
• Traceable refrigerant quantities
• Qualified service personnel
• Documented repairs and verification
• Controlled refrigerant recovery

Customer and occupant benefits

• More stable indoor temperatures
• Reliable domestic hot water
• Fewer system interruptions
• Clearer communication during service
• Greater confidence in the heat pump system

Selection criteria for a low-leak heat pump system

Refrigerant type

Identify the refrigerant, GWP and safety classification.

Purpose: Understand climate, safety and regulatory implications.

Benefit: Avoids selecting a product based on efficiency or purchase cost alone.

Selection question: Does the refrigerant suit the building, location and expected equipment lifetime?

Refrigerant charge

Review the refrigerant quantity in kilograms and, for F-gases, in CO₂ equivalent.

Purpose: Establish the maximum quantity that could be lost and determine possible regulatory duties.

Benefit: Supports charge minimisation and compliance planning.

Selection question: Can the same heating requirement be met with a lower refrigerant charge?

System architecture

Compare self-contained, split, indoor and multi-circuit designs.

Purpose: Identify where refrigerant is located and which connections are completed on site.

Benefit: Makes installation and service risks visible.

Selection question: Does the building benefit more from a factory-contained circuit or a split arrangement?

Number and type of joints

Review permanent joints, service valves and field connections.

Purpose: Reduce avoidable leak points.

Benefit: Supports long-term circuit integrity.

Selection question: Are the joints accessible for inspection without exposing them to accidental damage?

Site safety

Consider room volume, outdoor location, drainage, ventilation, ignition sources, building use and emergency access.

Purpose: Match refrigerant characteristics to the installation environment.

Benefit: Protects occupants, technicians and property.

Selection question: Does the proposed location meet the manufacturer’s instructions and applicable standards?

Monitoring capability

Review available data, alarms, histories and remote-service functions.

Purpose: Identify abnormal operation early.

Benefit: Faster diagnosis and more planned maintenance.

Selection question: Can the operator review heat output, energy use, runtime and fault history?

Service access

Check access to components, labels, sensors and service points.

Purpose: Allow safe inspection and repair.

Benefit: Shorter service time and better-quality maintenance.

Selection question: Can a qualified technician reach relevant components without major building work?

Installer and service competence

Verify certification, product training and refrigerant-specific experience.

Purpose: Ensure correct installation and safe handling.

Benefit: Lower risk of installation-created leakage.

Selection question: Does the company have the required certification and experience with this refrigerant?

In Austria, the Unternehmensserviceportal explains the certification requirements for companies carrying out F-gas work and recognises qualifying certificates issued in other EU Member States under Regulation 2024/573. The Austrian Environment Agency also maintains an F-gas helpdesk.

Documentation

Review commissioning forms, refrigerant labels and service records.

Purpose: Establish a complete technical baseline.

Benefit: Future faults can be assessed against known original conditions.

Selection question: Will the owner receive the refrigerant designation, charge, test results and maintenance requirements?

Regulatory durability

Consider future placing-on-the-market and service restrictions.

Purpose: Reduce exposure to refrigerant availability and regulatory change.

Benefit: Supports a long equipment life.

Selection question: Is the selected system compatible with the direction of EU refrigerant policy?

For example, EU placing-on-the-market restrictions become stricter from 2027 for several self-contained and split heat pump categories. Dates and limits depend on capacity, architecture, GWP and safety exceptions.

Total lifecycle performance

Compare more than direct refrigerant GWP.

Consider:

• Seasonal efficiency
• Refrigerant charge
• Expected leakage
• Recoverability
• Equipment life
• Repairability
• Electricity source
• Manufacturing impact
• End-of-life recovery
• Local service capability

A low-GWP heat pump that performs poorly or cannot be serviced is not automatically the best environmental choice. System efficiency, safety and lifecycle management must remain part of the decision.

Refrigerant leakage compared with other heat pump faults

The same symptom may have several causes. Reduced heating output does not prove refrigerant leakage. Correct diagnosis prevents unnecessary refrigerant work and component replacement.

Direct, indirect and automatic leak detection compared

The strongest approach combines methods. Operating data creates the warning. Direct testing confirms the leak. Repair removes the cause. Follow-up testing verifies the result.

Integration with other heat pump and building systems

Heat pump controller

• Definition: The controller manages compressor output, temperatures, pumps, valves and safety functions.
• Purpose: It keeps the heat pump within its operating range.
• Benefits: Fault histories and status data support faster diagnosis.
• Example: The controller records repeated low-pressure shutdowns before a service visit.

The controller should preserve fault codes rather than only displaying the latest alarm. Time-stamped history helps connect faults with weather, hot-water cycles or high-load operation.

Energy management system

• Definition: An energy management system coordinates heat-pump operation with building demand, electricity tariffs, photovoltaic production and storage.
• Purpose: It improves overall energy use.
• Benefits: Energy and heat-output trends create a performance baseline.
• Example: The system identifies that electricity input has increased without a corresponding increase in delivered heat.

An energy management system does not directly detect refrigerant. It supports problem recognition by showing that the relationship between input and useful output has changed.

Building management system

• Definition: A building management system connects heating, cooling, ventilation, alarms and meters.
• Purpose: It gives facility staff a central operational view.
• Benefits: Refrigerant alarms can trigger work orders and escalation procedures.
• Example: A fixed refrigerant sensor sends an alarm to the building management system and maintenance team.

Alarm design should distinguish between:

• Advisory performance deviations
• Service-required alarms
• Safety shutdowns
• Sensor faults
• Communication failures

Remote service

• Definition: Remote service allows authorised personnel to review status, history and operating data.
• Purpose: It supports diagnosis before an on-site visit.
• Benefits: The technician can arrive with suitable tools and replacement parts.
• Example: Remote analysis shows that a fault occurs only during high compressor load.

Remote access does not authorise refrigerant work from a distance. Physical leak location, circuit repair and refrigerant handling still require qualified on-site service.

Maintenance management system

• Definition: A maintenance management system stores inspections, repairs, parts and compliance tasks.
• Purpose: It converts leakage control into a repeatable process.
• Benefits: Scheduled checks and follow-up actions are less likely to be missed.
• Example: The system automatically creates a post-repair verification task.

Safety systems

• Definition: Safety integration connects refrigerant detection with alarms, ventilation, shutdown or access control where required.
• Purpose: It limits the consequences of a release.
• Benefits: The response starts quickly and follows a defined sequence.
• Example: A plant-room refrigerant alarm activates ventilation and alerts trained personnel.

The required response depends on refrigerant, charge, room design and applicable product or building standards. Alarm actions must be engineered rather than improvised after installation.

Refrigerant leakage management in an iDM heat pump system

The iDM NAVIGATOR energy manager is standard equipment across current iDM heat pump models. It provides live efficiency information, detailed status displays, operating information, statistics, remote access and support functions. These data can help users and service teams recognise unusual operating changes and prepare a more focused diagnosis.

NAVIGATOR data can support leakage management by showing:

• Changes in efficiency
• Longer operating times
• Recurring fault codes
• Temperature deviations
• Auxiliary heating use
• Historical performance trends
• Current equipment status

These functions do not replace a legally required leak check, a dedicated refrigerant sensor or direct testing by qualified personnel. They strengthen the information available before and during service.

iDM also offers heat pump models using the natural refrigerant R290. The iPUMP A ONE uses R290 and can provide flow temperatures up to 70°C. The iPUMP T7 ONE also uses R290 in a compact ground- or groundwater-source system.

The product-selection principle remains consistent:

1. Select a suitable heat source and capacity.
2. Select a refrigerant and system architecture suited to the site.
3. Minimise refrigerant charge and field connections where practical.
4. Follow product-specific installation and safety requirements.
5. Use connected operating data for performance transparency.
6. Maintain access to trained installation and service partners.
7. Document the complete refrigerant lifecycle.

EU refrigerant leakage requirements

Regulation (EU) 2024/573

The EU F-gas Regulation requires covered operators to:

• Avoid refrigerant emissions
• Take precautions against unintentional releases
• Repair detected leaks without undue delay
• Use certified or appropriately qualified personnel
• Perform periodic leak checks where thresholds are reached
• Keep required equipment and service records
• Recover refrigerant during repair and decommissioning
• Observe restrictions on refrigerant use and equipment placement

The regulation covers stationary heat pumps containing relevant Annex I gases and Section 1 Annex II gases.

General EU leak-check intervals

The following table summarises the European Commission’s operator guidance for stationary equipment. Site-specific status must be confirmed from the refrigerant, charge, labelling, equipment type and current national guidance.

The general periodic-check threshold starts at 5 tonnes CO₂ equivalent for Annex I gases or 1 kg for Section 1 Annex II gases. Hermetically sealed and correctly labelled equipment has specific exemptions below 10 tonnes CO₂ equivalent or 2 kg. Hermetically sealed equipment installed in residential buildings has a separate exemption where it contains less than 3 kg of F-gases.

For blends containing both Annex I and Section 1 Annex II substances, operators must examine both the CO₂-equivalent quantity and the relevant mass quantity. German Federal Environment Agency guidance expressly warns that both tests can matter.

Example thresholds for R410A and R32

German Federal Environment Agency guidance gives the following practical examples for the 5-tonne CO₂-equivalent threshold:

• Approximately 2.40 kg of R410A
• Approximately 7.41 kg of R32

Higher exemptions can apply to properly labelled hermetically sealed equipment. The exact duty must be determined from the nameplate, refrigerant, charge, equipment status and current regulation.

Operator responsibility

The “operator” is generally the person or organisation exercising actual control over the equipment’s technical functioning. Depending on ownership and contractual arrangements, this may be:

• A homeowner
• A landlord
• A property company
• A facility-management company
• A hotel operator
• An industrial business
• A public authority
• A tenant with technical control

Ownership alone does not always determine operational responsibility. Contracts should clearly state who arranges checks, repairs and records.

Qualified personnel

Technicians need the required certificate or training attestation for relevant installation, servicing, maintenance, repair, decommissioning, leak checking and refrigerant recovery work. Current EU certification requirements also address safe work with alternative refrigerants, including flammable, toxic and high-pressure substances.

Repair verification

A detected leak must be repaired without undue delay. For equipment subject to Article 5 periodic leak checks, the repair must later be checked for effectiveness. German authority guidance states that this check must occur after at least 24 operating hours and within one month of repair.

Record retention

Covered operators must retain relevant F-gas records for at least five years. Records should show the refrigerant type and quantity, additions, recovery, checks, repairs and responsible service provider.

Regulatory update effective 23 July 2026

Commission Implementing Regulation (EU) 2026/1444 repealed the older Regulations (EC) No 1497/2007 and No 1516/2007, which had prescribed detailed minimum leakage-checking methods. The Commission stated that these older approaches had been replaced in practice by current leak-checking methodologies used across the EU, so the regulations were repealed without replacement.

This change does not remove the core duties under Regulation 2024/573. Operators must still prevent emissions, arrange required checks, repair leaks, use qualified personnel, keep records and recover refrigerant.

Refrigerant leakage requirements in Austria

Austria applies Regulation (EU) 2024/573. Austrian rules and administrative structures provide for company certification, enforcement and national implementation.

The Austrian Unternehmensserviceportal explains that certification requirements aim to reduce or prevent F-gas emissions by ensuring that companies use suitably qualified personnel. It also states that certificates issued in other EU Member States in accordance with Regulation 2024/573 are recognised as equivalent in Austria.

For practical Austrian compliance:

• Confirm the refrigerant and charge from the nameplate.
• Determine the CO₂-equivalent quantity.
• Check whether the unit is labelled as hermetically sealed.
• Identify the responsible operator.
• Use an appropriately certified company.
• Retain installation and servicing records.
• Consult the Austrian Environment Agency F-gas helpdesk for current national guidance.

Refrigerant leakage requirements in Germany

Germany applies the EU F-gas Regulation and publishes detailed implementation guidance through the Umweltbundesamt.

German guidance confirms that private homeowners can fall within the operator definition when they exercise actual control over a covered heat pump. It also explains how to evaluate blends, leak-check thresholds and post-repair verification.

German operators should additionally verify:

• Current national certification requirements
• Documentation obligations
• Responsibilities agreed with maintenance companies
• State or local enforcement procedures
• Applicable technical rules and standards

Refrigerant leakage requirements in Switzerland

Switzerland is outside the EU F-gas Regulation. Refrigerants are regulated through Annex 2.10 of the Swiss Chemical Risk Reduction Ordinance, known as ChemRRV or ORRChem.

The Swiss Federal Office for the Environment states that these rules aim to reduce emissions of ozone-depleting and strongly climate-warming refrigerants. The framework includes tightness checks, maintenance records and equipment reporting. Stationary systems containing more than 3 kg of refrigerant are subject to the Swiss reporting procedure.

Swiss projects should therefore check:

• Current ChemRRV requirements
• BAFU technical guidance
• Refrigerant and charge restrictions
• Reporting duties
• Maintenance-log requirements
• Required professional authorisations
• Changes taking effect from 1 January 2027

EU compliance should not be treated as automatic proof of Swiss compliance.

Owner and facility manager checklist

Before installation

• Confirm the refrigerant type and safety class.
• Review the refrigerant charge.
• Compare self-contained and split architectures.
• Check the installation location.
• Confirm safety distances and room requirements.
• Select a qualified installation company.
• Require documented commissioning.
• Define who will act as operator.
• Establish a service and recordkeeping process.

During normal operation

• Keep equipment access clear.
• Review fault messages promptly.
• Compare current energy use with historical conditions.
• Monitor heating and hot-water performance.
• Do not ignore repeated low-pressure alarms.
• Protect outdoor equipment and pipes from mechanical damage.
• Keep the equipment label readable.
• Retain service records in one location.

When leakage is suspected

• Record the symptoms and fault code.
• Follow the manufacturer’s safety instructions.
• Do not open the refrigerant circuit.
• Keep ignition sources away where a flammable refrigerant release is suspected.
• Contact a qualified service provider.
• Ask for the leak location and root cause.
• Require repair rather than topping up alone.
• Obtain a written repair and refrigerant record.
• Complete any required follow-up check.

At end of life

• Use qualified personnel to decommission the heat pump.
• Recover the refrigerant.
• Record the recovered quantity.
• Send refrigerant for recycling, reclamation or destruction as appropriate.
• Retain the final equipment record.
• Dispose of components through approved channels.

Frequently asked questions

Is refrigerant normally consumed by a heat pump?

No. Refrigerant circulates inside a closed circuit and is not used as fuel. A significant reduction in charge indicates an incorrect original charge, service-related loss or leakage.

Can a heat pump operate with a refrigerant leak?

It may continue to operate during the early stage of a small leak. Output and efficiency can gradually decline. Continued operation can eventually cause alarms, shutdowns or component stress.

Does low refrigerant charge always mean there is a leak?

No. The heat pump may have been incorrectly charged during installation or previous service. A qualified technician must determine whether an active leak exists.

Can refrigerant simply be topped up?

Adding refrigerant can restore charge temporarily, but it does not repair an active leak. The defect should be located and corrected before final charging. Covered EU equipment must be repaired without undue delay.

Is water beneath an outdoor heat pump a refrigerant leak?

Usually, visible water is more likely to be condensate or defrost water. Refrigerant generally escapes as gas or as a gas-liquid mixture and may leave oil residue rather than a pool of refrigerant. Unusual liquid, odour, noise or equipment damage should still be assessed professionally.

How can a homeowner recognise a leak?

A homeowner may notice reduced heat, longer runtimes, increasing electricity use, repeated alarms, unusual frost or oil traces. These signs are not conclusive. Professional testing is required.

How often must a heat pump be checked for leaks?

The legal interval depends on refrigerant type, charge, CO₂-equivalent quantity, hermetically sealed status and whether a leakage detection system is installed. Under EU rules, covered intervals generally range from 3 to 24 months. Many small residential systems remain below the periodic-check threshold.

Does a low-GWP refrigerant make leakage unimportant?

No. Lower GWP reduces direct climate impact, but leakage can still reduce heat pump performance. Flammable, toxic or high-pressure refrigerants also require appropriate safety management.

Is R290 environmentally safe if it leaks?

R290 has a very low GWP of 0.02, so its direct climate impact is small compared with many HFCs. It is classified as A3 because of its higher flammability. Circuit integrity, charge limits and installation safety therefore remain essential.

Does smart monitoring replace leak detection?

No. Monitoring can identify abnormal efficiency, runtime or temperatures. It cannot normally confirm the physical leak location. Direct testing by qualified personnel remains necessary.

Can the refrigerant in an older heat pump be replaced with R290 or R32?

Not as a simple refill. Refrigerants have different pressure, temperature, lubrication, flammability and component requirements. A change is permitted only where the manufacturer has approved the conversion and all technical and legal requirements are met.

Who is responsible for arranging leak checks?

The operator exercising actual control over the equipment is generally responsible. This may be the homeowner, building owner, property manager, tenant or operating business. Contracts should state the responsibility clearly.

What should be included in a refrigerant service report?

The report should include the equipment identification, refrigerant type, charge, diagnosis, leak location, repair, refrigerant recovered or added, test results, technician details and required follow-up actions.